1. CONDITIONING SILICA GEL OUTSIDE THE EXHIBIT CASE
REMOVING MOISTURE
The most efficient method of removing moisture is with heat. Although silica gel has a very high melting temperature (1600º C), it will lose its chemically bound water and hygroscopic properties if heated above 300º C. In addition, there is a new class of indicator gels, incorporating organic dyes that are heat sensitive and their color indicating dye will be effected above 125-150º C (Goldberg and Weintraub 2001). Therefore, it is not recommended that indicating silica gel be heated above 120º C and regular gel be heated above 200º C. The principle impact of a lower heat of regeneration is that a longer time is required to dry the gel and there is less potential for the degradation of silica gel properties.
In a conventional oven, the time of regeneration varies from minutes to hours, depending on temperature and the thickness of the gel. Although silica gel can be dried in a microwave oven, it is difficult to determine the temperature inside the gel. Also, since metal cannot be used in a microwave oven, only glass, ceramic or microwave safe plastic with a high melting temperature should be used to hold the gel, since the individual beads can become very hot.
ADDING MOISTURE
The simplest method for conditioning silica gel is to place it in a room or environmental chamber set to the desired RH level. The best method of confirming that the silica gel is at the correct RH is by measuring the RH of a sample batch of gel. This is done by placing the sample gel in a sealed container or plastic bag with a hygrometer (use a large amount of gel relative to the surrounding air), and allow a day for the RH within the bag to stabilize with the gel mixture. Although an approximate RH value can be calculated based on weight, this method is not recommended because of its margin of error.
· Methods of speeding up conditioning time:
Spread the gel as thin as possible.
Use a fan to circulate air around the gel.
Periodically mix the gel layers to improve uniformity.
For a single layer of bead, allow at least 4 days if the gel is initially dry, and longer if spread as a thicker layer.
· Silica gel can be conditioned to a higher RH than the desired level, either to speed up the conditioning process or because of the inability to control RH. If so, it is important to allow 2-3 day for the moisture to equilibrate within and between the gel beads, especially if beads with different moisture contents are mixed together.
· The direct addition of water through mist spraying or immersion is not recommended, since the high heat of decrepitation causes silica gel beads to crack and fragment. Although silica gel retains its hygroscopic properties, the overall response time of silica gel in a tray will slow down because of denser packing from the mix of large beads and smaller fragments.
2. METHODS FOR CONDITIONING SILICA GEL WITHOUT REMOVING IT FROM THE EXHIBIT CASE
Silica gel in cases can be reconditioned by adding water or appropriately conditioned silica gel to the case. This method is very effective if the silica gel is spread into a very thin layer, or has a very fast response time, such as is achieved with Rhapid Gel. Otherwise, only the upper layer of silica gel will be conditioned and there is a risk that the RH within the case will rise or fall too quickly, without adequately conditioning the full bulk of silica gel.
Increasing or decreasing surface area can control the rate of water evaporation. If there is concern about placing water directly in a case, or if a fast rate of evaporation is desired, a saturated humidifier wicking pad, preferably one treated with an antimicrobial agent, can be used. Generally, water will evaporate more rapidly in this manner because of the extended surface area of the wicking pad compared to a dish of water.
The initial speed at which dry gel removes excess moisture is very fast. It is important to limit the surface area of dry gel to prevent the case RH from dropping too quickly. This is because the speed at which dry gel adsorbs moisture is faster than the rate at which silica gel desorbs moisture.
If silica gel is conditioned in place, the rate at which the RH rises or falls within the case must be carefully monitored in order to determine if the rate is acceptable and when the water or dry gel that was placed in the case to condition the main supply of silica gel must be removed.
It is possible to calculate how much moisture must be added or removed to recondition silica gel in place (Lafontaine 1984, Weintraub 1991). It is important to take into account the impact of other hygroscopic materials inside the case. With experience, adjusting the amount of water or dry gel required may be required to compensate for other hygroscopic materials.
CALCULATE THE AMOUNT OF WATER REQUIRED TO INCREASE RH:
Multiply the % increase in RH required, the MH value of the silica gel, and the weight of silica gel within the case.
For example, if the goal is to raise RH from 45% to 55% in a case containing 2 kilograms of silica gel with an MH of 9, 180 grams of water is required:
10% RH x 9 (MH) x 2 kg = 180 grams of water
CALCULATE THE AMOUNT OF DRY SILICA GEL REQUIRED TO DECREASE RH:
Step 1 - Determine how much moisture must be removed by multiplying the % decrease in RH required by the MH value of the silica and the total amount of silica gel within the case.
Step 2 - Establish the EMC adsorption value for the dry gel at the desired RH set-point and multiply this value by 10, to convert the value to the amount of moisture that can be removed per kilogram of dry gel.
Step 3 - Divide the amount of water to be removed (Step 1) by the amount of water that can be removed by a kilogram of dry gel (Step 2). The result is the total amount required to recondition the silica gel in place.
For example, the goal is to lower RH from 55% to 45% in a case containing 2 kilograms of Rhapid Gel (MH = 9). If the dry gel is a regular density silica gel (EMC = 25% at 45% RH), the amount of dry gel required is 0.72 kilograms:
1) 10% RH x 9 (MH) x 2 kg = 180 grams of water
2) 25% EMC x 10 = 250 g of moisture per kg of silica gel at 45% RH
3) 180g/250 g = 0.72 kilograms
AUTHOR’S ADDRESS
Steven Weintraub, Art Preservation Services, 315 East 89 Street, New York City, NY, 10128 (sw@apsnyc.org).
Extract from an article published in:
Object Specialty Group Postprints (vol. 9), 2002.
Washington, D.C.: American Institute for Conservation.
Senin, 25 Februari 2008
Introduction to Resin Craft (How to do Casting with Casting Polyester Resin)
These instructions provide an introduction to the general technique of casting with TAP Casting Resin. Important phases of resin craft, such as catalyzing the resin, coloring with transparent dyes or opaque pigments are covered.
With a little desire and imagination, you will be into a hobby that will give
you hours of enjoyment creating lovely items for your home or gifts for friends
and family.
Catalyzing or Curing Casting Resin
Many factors in.uence the speed of resin gel or cure. Most important of these are:
· amount of resin used
· temperature of the room
· temperature of the resin
· temperature of the mold
· additives, such as dyes, color pigments, pearl pigments and other types of embedments
There is an optimum amount of catalyst for each type of project. In all cases, refer to catalyzing instructions on the label.
Catalyst (hardener) starts a chemical reaction that creates an exotherm (heat) which cures the resin. An excessive amount of catalyst will overheat the casting, causing crystalization and fractures. Thicker pours require less catalyst because a thick casting retains heat. A thin section dissipates the heat requiring more catalyst.
Room temperature, resin temperature and the temperature of the mold affect gel time. (The higher the temperature, the faster the gel.) Too fast a cure will cause fractures. The high heat of the fast cure also causes excessive warping and fading of colors. Humidity slows the cure of resin. Moisture in the resin, which may come from humidity in the air or from temperature present in embedments, can cause the resin or casting to be cloudy. Keep the can of resin capped tightly when not in use.
Coloring TAP Casting Resin
Use TAP Dyes for transparent colors. Add dye to resin before adding the catalyst for thorough dispersion and resistance to fading from the catalyst reaction. The dye is concentrated, so use sparingly until you obtain the desired shade. One drop of TAP Transparent Dye per ounce will create a pastel shade; three drops per ounce will generally make quite a dark shade. Stir thoroughly.
Use TAP Premium Opaque Pigments for opaque castings. Color Pigments is most thoroughly dispersed by mixing in a small amount of resin, such as ¼ ounce color pigment to one ounce of resin. Then disburse the concentrated mixture into the balance of your resin.
For veins or streaks of color, add three drops of catalyst to resin and color mixture (add this mixture slowly to the resin, stiring only slightly). Pour slowly into the mold.
In small amounts, TAP Color Concentrate will make the resin or casting translucent rather than opaque. TAP Dyes and Color Concentrate cover the full range of transparency, translucency and opaqueness.
Always add the Color Concentrate .rst. This will give you time to obtain the desired shade and reduce the possibility of fading. After reaching the desired shade, add the catalyst. Do a little experimenting to obtain some very unusual and pleasing effects.
With a little desire and imagination, you will be into a hobby that will give
you hours of enjoyment creating lovely items for your home or gifts for friends
and family.
Catalyzing or Curing Casting Resin
Many factors in.uence the speed of resin gel or cure. Most important of these are:
· amount of resin used
· temperature of the room
· temperature of the resin
· temperature of the mold
· additives, such as dyes, color pigments, pearl pigments and other types of embedments
There is an optimum amount of catalyst for each type of project. In all cases, refer to catalyzing instructions on the label.
Catalyst (hardener) starts a chemical reaction that creates an exotherm (heat) which cures the resin. An excessive amount of catalyst will overheat the casting, causing crystalization and fractures. Thicker pours require less catalyst because a thick casting retains heat. A thin section dissipates the heat requiring more catalyst.
Room temperature, resin temperature and the temperature of the mold affect gel time. (The higher the temperature, the faster the gel.) Too fast a cure will cause fractures. The high heat of the fast cure also causes excessive warping and fading of colors. Humidity slows the cure of resin. Moisture in the resin, which may come from humidity in the air or from temperature present in embedments, can cause the resin or casting to be cloudy. Keep the can of resin capped tightly when not in use.
Coloring TAP Casting Resin
Use TAP Dyes for transparent colors. Add dye to resin before adding the catalyst for thorough dispersion and resistance to fading from the catalyst reaction. The dye is concentrated, so use sparingly until you obtain the desired shade. One drop of TAP Transparent Dye per ounce will create a pastel shade; three drops per ounce will generally make quite a dark shade. Stir thoroughly.
Use TAP Premium Opaque Pigments for opaque castings. Color Pigments is most thoroughly dispersed by mixing in a small amount of resin, such as ¼ ounce color pigment to one ounce of resin. Then disburse the concentrated mixture into the balance of your resin.
For veins or streaks of color, add three drops of catalyst to resin and color mixture (add this mixture slowly to the resin, stiring only slightly). Pour slowly into the mold.
In small amounts, TAP Color Concentrate will make the resin or casting translucent rather than opaque. TAP Dyes and Color Concentrate cover the full range of transparency, translucency and opaqueness.
Always add the Color Concentrate .rst. This will give you time to obtain the desired shade and reduce the possibility of fading. After reaching the desired shade, add the catalyst. Do a little experimenting to obtain some very unusual and pleasing effects.
Regenerating Silica Gel in a Micro-Wave
If you have a Microwave regenerating your Silica gel couldn't be easier, or quicker. As with regeneration in an electric oven, don't wait until you have a huge quantity to do, about 500gms at a time is a manageable amount. Place this in an open Micro-wave safe container, and with your setting on high micro-wave it for 2 minutes, then stir it mixing in any still green indicating crystals with the ones that have changed back to orange, and micro-wave again for 1 minute, repeat this process until all the indicating crystals have turned orange and voila your Silica Gel is ready to use again.
Drying Flowers in a Microwave
A microwave can be used to speed up the flower drying process. However, this method doesn’t work for all flowers. It’s best used for flowers with many petals and deep forms such as marigolds, roses, carnations, and zinnias. Flowers with thin, delicate petals or those with hairy or sticky surfaces are not as successful. Be sure to pick flowers that are about half-open and firm. Flowers that are in full bloom may be appealing to the eye, but they lose their petals easily. Also, keep colors in mind when selecting blooms. Yellow flowers retain their color well, but white ones may become dull gray-brown after drying. Dark red flowers and others with deep hues may become even darker during drying.
Harvest the flowers late in the afternoon when they are at a point of low water content. If the stems are cut off the flowers and only the heads are used, you should pre-wire them. This is particularly useful for roses, zinnias, and lilies to name a few. Once the flowers are dry, it is next to impossible to get them wired without shattering them.
After carefully selecting what you want to dry, the next step is to fill a glass, cardboard box, or other microwave-safe container to a depth of 1 to 2 inches with a supportive material such as silica gel. Silica gel, fine, white, sand-like material, is available at florist and craft shops as well as a number of other stores. It acts as a desiccant and is reusable as long as it is properly dried between uses. You can also use kitty litter or equal parts of borax and cornmeal instead of the silica gel. If you are attempting to dry flowers with very delicate petals, silica gel is preferred.
Place flowers, right side up, in the container. Space them so they do not touch each other or the sides of the container. A general guide is to allow at least 3/4 of an inch between flowers. Next, carefully sift silica gel over the tops of the flowers until they are covered. Work it around the blossoms so all flower surfaces are covered. You may need to tap the container to make sure the silica gel has settled properly. You can also use a toothpick to separate petals and help ensure they retain their original shape.
Place the silica gel-covered flowers in the microwave. Set the oven timer for the period listed in the table below for the particular flower you are drying. Note that some flowers only need 1 to 3 minutes of heating time while others require 5 to 8 minutes. Use a full-power cooking setting. The times given in the chart are only guidelines. The actual time may vary due to the type of oven and the amount of moisture in the flowers. If your oven does not have a turntable, you may want to rotate the containerevery 1/2 to 1 minute.
To test for dryness, use a toothpick to gently move away enough of the hot silica sand to see the petals. If they do not appear to be completely dry, place them back in the microwave oven and heat for one minute, making sure the flowers are completely recovered with the silica sand. It doesn’t take long; flowers can be over-cooked and become extremely brittle if heated too long. Experiment before you do large amounts.
After heating, remove the container from the microwave oven and leave the flowers in the silica sand overnight to allow the silica crystals to cool completely. The minimum standing times for the various flowers are given in the table below. When the silica sand has cooled, tip the container gently so the crystals flow off the flowers slowly. As the blooms become uncovered, carefully slide two fingers under each and lift out. Shake the flowers gently and use a fine, soft brush to remove any remaining crystals. If you don’t plan to use the flowers immediately, store them in a plastic bag or box of shredded newspaper to help them hold their shape.
If you used silica gel as the drying agent, you can save it and re-use it but it must be reactivated. You can do this by spreading the silica gel on a cookie sheet and heating it in an oven at 250 –300o for 2 to 3 hours. Silica gel should be reactivated when the color indicator begins to turn pink. As it is reactivated, the color indicator will turn blue.
Recommended Drying and Standing Times
for Flowers Dried in Microwave
Drying Time Standing time
(in minutes) (in hours)
Anemone (Anemone sp.) 2 1/2 to 3 12
Aster (Aster sp.) 2 1/2 10
Calendula (Calendula officinalis) 2 1/2 10
Carnation (Dianthus caryophyllus) 1 10
Chrysanthemum (Chrysanthemum sp.) 3 10
Daffodil (Narcissus sp.) 2 1/2 10
Dahlia (Dahlia hybrids) 5 to 7 36
Delphinium (Delphinium elatum) 4 to 5 10
Marigold (Tagetes sp.) 2 1/2 to 3 10
Pansy (Viola x wittrockiana) 2 1/2 to 3 36
Peony (Paeonia hybrids) 3 to 4 36
Poppy (Papaver orientale) 2 1/2 to 3 24
Rose (Rosa sp.) 1 1/2 to 2 10
Salvia (Salvia sp.) 3 24
Tulip (Tulipa sp.) 3 24
Zinnia (Zinnia sp.) 4 to 5 10
James C. Schmidt, HorticulturistUniversity of Illinois
Harvest the flowers late in the afternoon when they are at a point of low water content. If the stems are cut off the flowers and only the heads are used, you should pre-wire them. This is particularly useful for roses, zinnias, and lilies to name a few. Once the flowers are dry, it is next to impossible to get them wired without shattering them.
After carefully selecting what you want to dry, the next step is to fill a glass, cardboard box, or other microwave-safe container to a depth of 1 to 2 inches with a supportive material such as silica gel. Silica gel, fine, white, sand-like material, is available at florist and craft shops as well as a number of other stores. It acts as a desiccant and is reusable as long as it is properly dried between uses. You can also use kitty litter or equal parts of borax and cornmeal instead of the silica gel. If you are attempting to dry flowers with very delicate petals, silica gel is preferred.
Place flowers, right side up, in the container. Space them so they do not touch each other or the sides of the container. A general guide is to allow at least 3/4 of an inch between flowers. Next, carefully sift silica gel over the tops of the flowers until they are covered. Work it around the blossoms so all flower surfaces are covered. You may need to tap the container to make sure the silica gel has settled properly. You can also use a toothpick to separate petals and help ensure they retain their original shape.
Place the silica gel-covered flowers in the microwave. Set the oven timer for the period listed in the table below for the particular flower you are drying. Note that some flowers only need 1 to 3 minutes of heating time while others require 5 to 8 minutes. Use a full-power cooking setting. The times given in the chart are only guidelines. The actual time may vary due to the type of oven and the amount of moisture in the flowers. If your oven does not have a turntable, you may want to rotate the containerevery 1/2 to 1 minute.
To test for dryness, use a toothpick to gently move away enough of the hot silica sand to see the petals. If they do not appear to be completely dry, place them back in the microwave oven and heat for one minute, making sure the flowers are completely recovered with the silica sand. It doesn’t take long; flowers can be over-cooked and become extremely brittle if heated too long. Experiment before you do large amounts.
After heating, remove the container from the microwave oven and leave the flowers in the silica sand overnight to allow the silica crystals to cool completely. The minimum standing times for the various flowers are given in the table below. When the silica sand has cooled, tip the container gently so the crystals flow off the flowers slowly. As the blooms become uncovered, carefully slide two fingers under each and lift out. Shake the flowers gently and use a fine, soft brush to remove any remaining crystals. If you don’t plan to use the flowers immediately, store them in a plastic bag or box of shredded newspaper to help them hold their shape.
If you used silica gel as the drying agent, you can save it and re-use it but it must be reactivated. You can do this by spreading the silica gel on a cookie sheet and heating it in an oven at 250 –300o for 2 to 3 hours. Silica gel should be reactivated when the color indicator begins to turn pink. As it is reactivated, the color indicator will turn blue.
Recommended Drying and Standing Times
for Flowers Dried in Microwave
Drying Time Standing time
(in minutes) (in hours)
Anemone (Anemone sp.) 2 1/2 to 3 12
Aster (Aster sp.) 2 1/2 10
Calendula (Calendula officinalis) 2 1/2 10
Carnation (Dianthus caryophyllus) 1 10
Chrysanthemum (Chrysanthemum sp.) 3 10
Daffodil (Narcissus sp.) 2 1/2 10
Dahlia (Dahlia hybrids) 5 to 7 36
Delphinium (Delphinium elatum) 4 to 5 10
Marigold (Tagetes sp.) 2 1/2 to 3 10
Pansy (Viola x wittrockiana) 2 1/2 to 3 36
Peony (Paeonia hybrids) 3 to 4 36
Poppy (Papaver orientale) 2 1/2 to 3 24
Rose (Rosa sp.) 1 1/2 to 2 10
Salvia (Salvia sp.) 3 24
Tulip (Tulipa sp.) 3 24
Zinnia (Zinnia sp.) 4 to 5 10
James C. Schmidt, HorticulturistUniversity of Illinois
Microwave Flower Drying Instructions
To dry a fresh flower in your microwave you’ll need a large microwave safe glass jar or narrow glass container, silica gel, a toothpick, a cup of water, and a freshly cut flower of your choice. To dry more you’ll need additional silica gel and another glass container, or you’ll need to wait until the silica gel you’ve used is completely cool. Fill the glass container of your choice one-third of the way full with silica gel, remove the leaves, and carefully put the flower into the silica granules, bloom first. Use a toothpick to place the granules between the petals, and continue to add silica gel until the flower and stem are completely covered.
Place a cup of water in your microwave near the back corner of the unit or near the edge of the revolving tray, and place the glass jar with the silica gel and flower in the center. The average drying time in a 700-watt microwave oven is about two minutes. Since microwave ovens vary, experiment with various types of flowers and heating times. Take notes regarding how long various types take to dry in your microwave oven. After removing the jar containing the silica gel and flower from the microwave, you must let it stand to complete the drying process. Most flowers must stand in the silica gel for ten minutes before removing, and sunflowers must remain in the gel for about eighteen hours with the jar covered by a plastic bag. It’s obviously better to leave the flower in the silica for a longer period of time than removing it too soon. To remove the flower from the jar, carefully pour the granules into another container, and carefully remove the dried flower. Carefully remove any silica gel trapped between the petals. As stated before, don’t reuse the silica gel until it’s completely cool.
The flowers may require assistance in standing, and they can be supported with florist wire. Also, if you’ve dried the leaves separately as instructed above, the leaves can be attached with florist tape, florist wire, or super glue.
Place a cup of water in your microwave near the back corner of the unit or near the edge of the revolving tray, and place the glass jar with the silica gel and flower in the center. The average drying time in a 700-watt microwave oven is about two minutes. Since microwave ovens vary, experiment with various types of flowers and heating times. Take notes regarding how long various types take to dry in your microwave oven. After removing the jar containing the silica gel and flower from the microwave, you must let it stand to complete the drying process. Most flowers must stand in the silica gel for ten minutes before removing, and sunflowers must remain in the gel for about eighteen hours with the jar covered by a plastic bag. It’s obviously better to leave the flower in the silica for a longer period of time than removing it too soon. To remove the flower from the jar, carefully pour the granules into another container, and carefully remove the dried flower. Carefully remove any silica gel trapped between the petals. As stated before, don’t reuse the silica gel until it’s completely cool.
The flowers may require assistance in standing, and they can be supported with florist wire. Also, if you’ve dried the leaves separately as instructed above, the leaves can be attached with florist tape, florist wire, or super glue.
Steps On How To Embed A Reptile, an Amphibian, or a Fish.
As in the case with insects, water moisture inside of your specimen is your worst enemy. You cannot dry these kinds of species as you dry an insect without doing a lot of damage to your specimen. For example for lizard specimens.
First, soak the dead lizard real good in alcohol. Let it soak for over 48 hours or so and inject alcohol through a hyperdermic needle into each of it's shoulders and hips. Take an eye dropper and force the liquid down it's throat.
Remove the specimen from the soaking jar, place it on a paper towel, and leave it overnight to drain real good. The next day you are ready to embed it.
The mold is like a large bowl. Apply the mold release real good to the mold. Then measure out the plastic resin, mix it with the hardener, and pour the base layer. If you want the base layer clear and want others to be able to look at the belly of the lizard.
Next pour a thin layer of liquid plasic on top of the base layer, insert the lizard inside of the mold and curl his tail around so no part of it's tail is touching any part of the mold. I work out any air bubbles that may be around the bottom of the lizard. Then I give it a couple of hours to set up. Up to this point only the bottom part of the lizard and his feet are touching any of the plastic resin. Now the resin is pretty firm and I can be assured that the lizard is not going to float around or drift in any more of the resin that I pour.
One secret here is to try to reduce the amount of heat that the hardening plastic is giving off. The best way to do this is to pour thin layers at a time. Say, only 1/8 inch thick at a time. Remember that too much heat all at once will affect the moisture content inside of the specimen. This heat will affect the liquid alcohol in the specimen in nearly the same way that it would have affected the water moisture in the specimen if you had not treated it. Just keep on pouring one thin layer after another with about 4 hours or so in between the pouring of each layer. Then finish covering your specimen with resin. Let the entire work dry for about 2 full days or so.
If you get silvering then you know you did something wrong. Try it again on another specimen using the trial and error method until you get a good specimen without silvering. Keep notes if you have to on each of your experiments until you find the way that works best for you.
Kraig J. Rice. 2005. Plastic Embedding As A Hobby.
Steps On How To Embed An Insect
So, let's pick out the round plastic mold that we want to use and measure the amount of plastic that we want to use (as stated above). I want to make a paper weight this time.
Small insects can be dryed easily. There are all kinds of ways of doing this without using alcohol. If you just catch your insect and immediately embed it in plastic without dealing with the water content problem then you will probably get silvering.
This time let's do it a little different. I want a blue bottom layer but I want the plastic on top of the bug to be clear. Remember that we are working backwards so our base layer has to be clear resin. Then the last layer that I pour will have to be blue.
Now, here is the trick. We are only going to embed half of our bug at a time. You don't want to place your bug on the hardened base layer just yet. If you do you will likely get air bubbles underneath it.
Pour a thin layer of liquid plastic into the mold on top of the base layer. Then carefully insert the bug upside down into the liquid resin being careful not to break it's wings, antennae, or legs. Carefully push the bug all the way to the bottom as it will have a tendency to float. Take the sharpened end of your pencil to work out the surface bubbles. You can also use a long sharp nail or an ice pick if you prefer. Use the eraser end of your pencil to work out any bubbles under the butterfly's wings. If you break off a leg or antennae or wing wait until the next pour to carefully fit it back on, letting the liquid resin help you hold it in place. You might have to use a pair of tweezers to help you move it around in the plastic.
So far, only half of the bug has been stuck to the plastic. That's what you want. The resin will put out a certain amount of heat while it is drying. This heat will also help dissipate any additional water moisture that might be inside of the bug. When this happens the moisture can escape through the upper end of the bug because it is not covered with plastic yet. This way you let the heat from the plastic resin work for you rather than against you. Let this set up for 4 hours or so. Mix some more resin and then cover the bug entirely with it. Work out any air bubbles that you may have.
Some embedders don't like to embed half of their bug at a time. Here is a tip if you want to embed it all at once. Use one or two drops less hardener here. This will allow the plastic to dry slower thus putting out less heat. The insect may have a tendency to slide or float in this layer so you need to check the casting frequently. It may harden off-centered if you don't correct it. If it does float off-centered then carefully take the eraser end of your pencil and move it back to center again. You can only do this if the plastic has not set up yet. If the plastic has set up then it is too late. You have to live with it because there is nothing that you can do.
Now it's time to pour our last and final layer. Let's add a few drops of blue coloring (pigment) to the liquid plastic that is in our paper cup. We add the coloring and stir it into the resin before we add the hardener. Then we add the hardener and stir it all up real good and then pour it into the mold. Let this dry for 48 hours or so. After you take your finished product out of the mold then you may want to cut a small circular amount of felt cloth and glue it to the bottom to make an attractive looking paper weight and conversation piece.
Kraig J. Rice. 2005. Plastic Embedding As A Hobby.
Small insects can be dryed easily. There are all kinds of ways of doing this without using alcohol. If you just catch your insect and immediately embed it in plastic without dealing with the water content problem then you will probably get silvering.
This time let's do it a little different. I want a blue bottom layer but I want the plastic on top of the bug to be clear. Remember that we are working backwards so our base layer has to be clear resin. Then the last layer that I pour will have to be blue.
Now, here is the trick. We are only going to embed half of our bug at a time. You don't want to place your bug on the hardened base layer just yet. If you do you will likely get air bubbles underneath it.
Pour a thin layer of liquid plastic into the mold on top of the base layer. Then carefully insert the bug upside down into the liquid resin being careful not to break it's wings, antennae, or legs. Carefully push the bug all the way to the bottom as it will have a tendency to float. Take the sharpened end of your pencil to work out the surface bubbles. You can also use a long sharp nail or an ice pick if you prefer. Use the eraser end of your pencil to work out any bubbles under the butterfly's wings. If you break off a leg or antennae or wing wait until the next pour to carefully fit it back on, letting the liquid resin help you hold it in place. You might have to use a pair of tweezers to help you move it around in the plastic.
So far, only half of the bug has been stuck to the plastic. That's what you want. The resin will put out a certain amount of heat while it is drying. This heat will also help dissipate any additional water moisture that might be inside of the bug. When this happens the moisture can escape through the upper end of the bug because it is not covered with plastic yet. This way you let the heat from the plastic resin work for you rather than against you. Let this set up for 4 hours or so. Mix some more resin and then cover the bug entirely with it. Work out any air bubbles that you may have.
Some embedders don't like to embed half of their bug at a time. Here is a tip if you want to embed it all at once. Use one or two drops less hardener here. This will allow the plastic to dry slower thus putting out less heat. The insect may have a tendency to slide or float in this layer so you need to check the casting frequently. It may harden off-centered if you don't correct it. If it does float off-centered then carefully take the eraser end of your pencil and move it back to center again. You can only do this if the plastic has not set up yet. If the plastic has set up then it is too late. You have to live with it because there is nothing that you can do.
Now it's time to pour our last and final layer. Let's add a few drops of blue coloring (pigment) to the liquid plastic that is in our paper cup. We add the coloring and stir it into the resin before we add the hardener. Then we add the hardener and stir it all up real good and then pour it into the mold. Let this dry for 48 hours or so. After you take your finished product out of the mold then you may want to cut a small circular amount of felt cloth and glue it to the bottom to make an attractive looking paper weight and conversation piece.
Kraig J. Rice. 2005. Plastic Embedding As A Hobby.
Steps On How To Embed An Inanimate Object
First of all I'll work in a well-ventilated area- preferably outside. Plastic resin puts off a tremendous amount of odor and fumes while it is hardening so you need to go to an isolated location where you don't have to breathe it. Another location might be an isolated work shop or back storage shed that is separate from your house. Anywhere where there is good ventilation with no people or animal pets living is usually fine.
I spread a thick coating of newspapers on the work bench. Spilled plastic is hard to clean up so it is good to use rags or newspapers to cover the bench where you are working. That way, you can just throw them away when you are finished.
Wear protective gear when using resin including goggles, gloves, and a facemask or respirator.
Using water - measure how much liquid your mold will hold. Pour 1/8 cup of water into 3 disposable plastic cups. Mark the water line with a pen (figure A). Our mold will hold about 1/2 cup so we will repeat the mixing process several times.
Spray mold with cooking spray.
Wearing safety gear and working in a well-ventilated area, preferably outside - measure out 1/8 cup of resin and add 6 drops of the hardening catalyst. Mix with a craft stick thoroughly according to manufacturer directions.
Pour into the mold and let it harden to a jelly stage, about 25 minutes. Throw the cup and craft stick away in a trash can outside.
Now, lay your item to be sealed on the jelly hardened resin. Repeat the process. Measure another 1/8 cup of resin, but his time only add 4 drops of the catalyst. Mix and pour into the mold (figure B). Let it set another 25 minutes. This is when you can add a written saying. Be patient, mixing resin so that it sets right can be tricky so start with an easy object to encase.
Repeat the same measurements one more time. DON'T OVERFILL the mold. In all, our mold took 3 layers of resin to complete.
Let mold cure for 24 hours. Top of the mold should "click" hard and not be "tacky" to the touch. If you have trouble getting the mold to release, run it under hot water and carefully push it out. Let it stand in the open air for an hour or two. If you touch it immediately, it may pick up your fingerprints and become cloudy.
Preparing Your Specimen
Silvering and bubbles are the two major faults one has to overcome in the resin casting. Silvering happens when the abdomen shrinks away from the plastic. This happens when the specimen is hardening in the plastic.
Some more examples of specimens to embed might include: a crayfish, clam, frog, perch, starfish, or a worm.
The main problem with embedding your specimen is the water content inside of the specimen. Most water is found in the abdominal cavity as part of it's abdominal juices. This water problem has to be dealt with before you embed your specimen. This water content is what is behind silvering. The water in the abdomen of the specimen will shift or change thus taking away it's partial support of the specimen's outer skin or covering. When this happens the skin or outer covering will shrink away from the plastic that is around it causing silvering to take place.
For a small bug specimen- make sure that it has been fully dried and that there is little water moisture inside of it. This is not difficult for rather small insects. However, this may prove difficult for rather large insects. These insects do not dry easily, especially if you have a large spider, a large moth, or a large grasshopper. If you try to dry these kinds then they will wind up looking shriveled and deformed. This is not a good senario.
There are two ways to solve this problem on large species of insects, for fish, reptiles and amphibians, as well.
The first method to get rid of water content is for you to be part taxidermist. A taxidermist stuffs animals. Turn your specimen upside down and cut open it's abdominal cavity and pull out it's guts with a pair of tweezers. Once the guts are removed you can replace the abdominal cavity parts with dry packing material such as small round pieces of toilet paper, napkins, or cotton balls. Superglue or stitch the incision back together after you have finished your operation. These dry items inside of your specimen should hold the outer wall of the abdomen in place against the plastic when it is poured against it.
The second method to get rid of water content is to soak your specimen in alcohol. Why? Because you don't want silvering. Also because you need to preserve your specimen against decay as long as you can. This is especially true once your specimen is encased in hard plastic resin.
Basically, you should not use liquid alcohol on small insects or other small specimens that you intend on immediately embedding as small insects can dry well. Hard shelled specimens usually embed well with little or no use of alcohol. This would include a small crab, scorpion, or horned beetle. Give it the trial and error method if you have any doubts.
This is not rubbing alcohol (isopropryl alcohol). Rather, it is called denatured ethanol. Because of it's dehydration and other properties it is considered poisonous to one's body.
If you place your specimen in alcohol then it will start to dehydrate the cells of your specimen. In other words tissue water is replaced by the alcohol. This is good for long term preservation.
Soaking in alcohol is optional for small specimens but is recommended for large specimens. A large specimen is any that is over 1/2 inch in thickness. It should be soaked for a couple of days. Make sure that your specimen is completely submerged under the level of the alcohol. For instance, the lizard that I caught in the back yard was considered a large specimen.
Soaking in alcohol is optional for small specimens but is recommended for large specimens. A large specimen is any that is over 1/2 inch in thickness. It should be soaked for a couple of days. Make sure that your specimen is completely submerged under the level of the alcohol. For instance, the lizard that I caught in the back yard was considered a large specimen.
Here is another tip: if your specimen is 1/2 inch or more in thickness then take a hyperdermic needle and syringe and inject alcohol into it's abdomen, shoulders and hips. You have to do this because sometimes the alcohol does not soak that far down into the deeper tissue without your help. When finished, take your specimen out of the alcohol and then let it drain real good overnight in the open on a paper towel.
Kraig J. Rice. 2005. Plastic Embedding As A Hobby.
Preserving Plant Materials
Drying with Desiccants
Plant materials which wilt readily must be dried in a supportive material. The two most satisfactory are a sand-borax mix and silica-gel. Others, such as kitty litter, perlite, sawdust, cornstarch and cornmeal, can be used but are not as reliable.
Plant materials which wilt readily must be dried in a supportive material. The two most satisfactory are a sand-borax mix and silica-gel. Others, such as kitty litter, perlite, sawdust, cornstarch and cornmeal, can be used but are not as reliable.
Borax-sand: A mixture of 2 parts borax with 1 part fine sand is an inexpensive, yet effective desiccant medium. Drying by this method takes 4-14 days, depending on the material being dried. Adding 3 tablespoons of uniodized salt to each quart of this mixture will help flowers retain their original color. The material is lightweight and faster than using only sand. Do not use borax alone, as it may cause bleaching.
Silica-gel: Silica-gel is especially effective for drying delicate flowers. It is lighter than borax-sand and is the fastest drying agent available. (A quicker drying time usually means a truer blossom color.) Drying usually takes 2-7 days. It may be purchased from florists or garden centers as well as hobby and craft shops. Silica-gel crystals are expensive but may be used indefinitely. As the crystals absorb moisture, they turn from bright blue to pinkish gray. To reuse, they must be dried by placing in a shallow pan in a warm oven (250-275o F) for several hours. A microwave oven takes only a few minutes. The crystals should return to their original blue color when dry. Store in an airtight container.
How to use desiccants. Choose containers such as boxes and cans that will allow the material to be dried without overlapping or crowding. Pour 1/2 inch of desiccant into the bottom of the container. Place the first layer of flowers on top. Flat-faced flowers such as daisies may be placed face down; all others should be arranged face up. Gently place the drying agent around and over the flowers. Be careful to retain form and keep petals in their natural position. Add desiccant until the flower heads are covered.
It is a good idea to have a test flower conveniently located in the container to permit a check on the dryness without disturbing the entire contents. Cover the container and do not disturb.
Drying is complete when flowers are crisp and dry but not brittle. The thickest parts are slowest to dry. If only the petals are completely dry, the flower may be removed and air dried to complete the process.
To remove dried flowers, gently pour off desiccant. Wisk away any remaining drying medium with a soft brush. After drying, white or clear glue may be placed at the base of some flower petals to prevent shattering.
Microwave Oven Drying
Microwave drying takes only a few minutes and provides material that looks fresher and more colorful than that obtained by other methods. Use a desiccant such as silica-gel to support the flowers in a glass or special microwave container. Do not cover the container. Always place a cup of water in the oven before starting to prevent excessive drying.
Drying times vary (see Table 1). A standing period following drying is necessary to allow cooling and complete drying.
Table 1. Microwave Oven Flower Drying Times
___________________________________________________
Heating Standing
Flower Time Time
(minutes) (hours)
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African Daisy 3 10
Aster 2-1/2 10
Calendula 2-1/2 10
Carnations 1 10
Clematis 3 10
Chrysanthemum 3 10
Daffodil 2-1/2 10
Dahlia 5 to 7 36
Delphinium (Larkspur) 4 to 5 10
Dianthus 3 10
Dogwood 2-1/2 24
Marigold 3 10
Orchid 1-1/2 to 2-1/2 24
Pansy 2-1/2 to 3 24
Peony 3 to 4 36
Poppy 2-1/2 to 3 24
Rose 1-1/2 10
Salvia 3 24
Scilla 2-1/2 10
Tithonia (Mexican Sunflower) 5 to 6 10
Tulip 3 24
Violet and Viola 2-1/2 to 3 10
Zinnia 4 to 5 10
___________________________________________________
Michael N. Dana and B. Rosie Lerner. 2008. Preserving Plant Materials. Department of
Horticulture Purdue University Cooperative Extension Service • West Lafayette, IN
Items, Chemicals and Equipment for Resin Casting
Items needed:
- sample container with living specimens
- tweezers
- pipette to count drops of catalyst
- disposable wooden stir stick
- cups for mixing
- molds for casting, e.g. made of polypropylene, latex, natural rubber, flexible vinyl plastic, e.g.reusable molds (Note: Some mold types require the use of a mold release to keep the casting from sticking to the molds)
- or acrylic box with magnifier cover - large 1.5” x 1.5” x 1.5” or small - 1” x 1” x 0.75” as permanent
- preservation boxes instead of reusable molds, from which you remove the casting after it has cured
Chemicals:
- casting resin and catalyst, e.g. Clear Polyester Casting Resin with catalyst or Easy Cast Clear Casting Epoxy
- mold release/conditioner to clean and condition molds for longer use
- ethanol 95 %
- acetone or rubbing alcohol for clean up instruments
Equipment:
- fume hood or other well-ventilated area! (resin causes strong styrene vapor during curing)
- level working surface, covered with layers of wax paper
- Gloves
- Newspaper or plastic bags (for work surface)
- Goggles
Grit May and Joe Courneya. 2008. Lesson Plan: Creating a classroom collection of Macroinvertebrates. CWE Project Specialist. NDSU Extension Educational Design Specialist.
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