Hjholter3
New Member
As promised in an earlier thread I decided to share some tricks I've learned to hopefully help anyone new to modeling :cool
Casting resin with a Blue-Tac mold
Blue-tac is a pressure sensitive adhesive usually used to hang posters; We as modelers use it as mask for painting, a base for objects to painted, and in this tutorial a molding material. As a synthetic rubber compound it can be ideal for simple, single use open face molds. This technique however has a few caveats that must not be overlooked - for one the mold is will be single use as removing the cast will destroy the mold - unlike RTV or liquid molding silicone Blue-tac will never cure and is quite sticky.
Materials Used in this tutorial
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1. Loctite "Fun-Tak"
2. 1/2 TSP (2.5 ml) metal measuring spoon
3. Alumilite Amazing two part casting resin
4. Clear "Condiment" Cup
5. Small plastic straw ( a Capri-sun Straw )
6. Vaseline 100% Petroleum jelly 2.5 oz tube
7. Saucer Section, 1701-A, 1/2500 scale, ( pattern object )
8. Precut cardboard base for mold
STEP ONE: Preparing the mold base and pattern object
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The pattern object in this tutorial is the bridge portion of the saucer of the 1/2500 Enterprise A.
Looking at the pattern object, I determined the amount of blue-tac to apply - enough in this case to allow one and a half centimeters of perimeter so as to act as a "bowl" for the resin. The cardboard is essential so the blue tac will not deform as you remove the pattern object and provides a base so you can move the mold while the resin cures. I used a flat metal ruler to produce an even surface for molding. To prepare the pattern object, I used my finger to apply a very thin coating of Vaseline to the saucer to act as a demolding agent.
Step Two: Making the mold
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To make the mold, I pressed the saucer as evenly as possible into the blue-tac surface. The aim here is to make the surface of the cast which will be the bottom be as flat and neat as possible to save work latter on sanding or cutting, and at the same time provide a measured amount of extra area so as to be sure we will have the entire part we intend to cast.
Step Three: Demolding and estimating the amount of resin for the cast
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to demold the part, gently pull the part from the blue-tac surface as evenly as possible to leave a clean molding cavity. This done, we must estimate the amount of resin we will need to fill this cavity. In this case, the mold cavity appears slightly smaller than half of my metal 1/2 teaspoon.
Step Four: Marking the measuring instrument.
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In this case, I'm using 1:1 mix casting resin, so I marked my measuring spoon at the level I felt would give the amount I needed to fill the molding cavity when doubled. I poured part A to the mark in the spoon, and then poured that in my condiment cup, and then repeated the process with part B.
Step Five: mixing the resin.
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Using my Capri-Sun Straw I mix the resin in the condiment cup. At this point, depending on the resin used, your time is limited to get the resin in the mold - The "pot-life", or the time before the resin is too viscous to put in the mold satisfactorily is in the documentation is 2.5 minutes so be ready to perform the next step IMMEDIATELY after.
Step Six: "pouring" the resin
Uploaded with ImageShack.us
Uploaded with ImageShack.us
in this case we are not pouring the resin, but gathering resin in the end of the straw and by pressing a finger on the other end creating a vacuum, and then applying the resin in the mold. Once you position the straw over the mold you can blow very gently into the end of the straw to empty it. I have used my mouth to apply a vacuum, but this is not a good idea, and you do so at your own risk.
Step Seven: Allow the resin to cure.
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Any resin will require a certain amount of time to cure. Alumilite's claimed demold time for Amazing casting resin is 5-15 minutes, so I allow 10 minutes. Usually it will require less, but better to be safe than sorry. This resin appears white when cured, as in the image above.
Step Eight: demold and clean up the casting
After the resin has cured, gently pull up around the corners towards the center until you have it completely removed the mold. In this case some Blue-Tac has come with it, and it will need some clean up, but afterwards it is satisfactory.
Hopefully, this will help someone or inspire someone to try resin casting to supplement the modeling techniques they already possess.
Casting resin with a Blue-Tac mold
Blue-tac is a pressure sensitive adhesive usually used to hang posters; We as modelers use it as mask for painting, a base for objects to painted, and in this tutorial a molding material. As a synthetic rubber compound it can be ideal for simple, single use open face molds. This technique however has a few caveats that must not be overlooked - for one the mold is will be single use as removing the cast will destroy the mold - unlike RTV or liquid molding silicone Blue-tac will never cure and is quite sticky.
Materials Used in this tutorial
Uploaded with ImageShack.us
1. Loctite "Fun-Tak"
2. 1/2 TSP (2.5 ml) metal measuring spoon
3. Alumilite Amazing two part casting resin
4. Clear "Condiment" Cup
5. Small plastic straw ( a Capri-sun Straw )
6. Vaseline 100% Petroleum jelly 2.5 oz tube
7. Saucer Section, 1701-A, 1/2500 scale, ( pattern object )
8. Precut cardboard base for mold
STEP ONE: Preparing the mold base and pattern object
Uploaded with ImageShack.us
The pattern object in this tutorial is the bridge portion of the saucer of the 1/2500 Enterprise A.
Looking at the pattern object, I determined the amount of blue-tac to apply - enough in this case to allow one and a half centimeters of perimeter so as to act as a "bowl" for the resin. The cardboard is essential so the blue tac will not deform as you remove the pattern object and provides a base so you can move the mold while the resin cures. I used a flat metal ruler to produce an even surface for molding. To prepare the pattern object, I used my finger to apply a very thin coating of Vaseline to the saucer to act as a demolding agent.
Step Two: Making the mold
Uploaded with ImageShack.us
To make the mold, I pressed the saucer as evenly as possible into the blue-tac surface. The aim here is to make the surface of the cast which will be the bottom be as flat and neat as possible to save work latter on sanding or cutting, and at the same time provide a measured amount of extra area so as to be sure we will have the entire part we intend to cast.
Step Three: Demolding and estimating the amount of resin for the cast
Uploaded with ImageShack.us
to demold the part, gently pull the part from the blue-tac surface as evenly as possible to leave a clean molding cavity. This done, we must estimate the amount of resin we will need to fill this cavity. In this case, the mold cavity appears slightly smaller than half of my metal 1/2 teaspoon.
Step Four: Marking the measuring instrument.
Uploaded with ImageShack.us
In this case, I'm using 1:1 mix casting resin, so I marked my measuring spoon at the level I felt would give the amount I needed to fill the molding cavity when doubled. I poured part A to the mark in the spoon, and then poured that in my condiment cup, and then repeated the process with part B.
Step Five: mixing the resin.
Uploaded with ImageShack.us
Using my Capri-Sun Straw I mix the resin in the condiment cup. At this point, depending on the resin used, your time is limited to get the resin in the mold - The "pot-life", or the time before the resin is too viscous to put in the mold satisfactorily is in the documentation is 2.5 minutes so be ready to perform the next step IMMEDIATELY after.
Step Six: "pouring" the resin
Uploaded with ImageShack.us
Uploaded with ImageShack.us
in this case we are not pouring the resin, but gathering resin in the end of the straw and by pressing a finger on the other end creating a vacuum, and then applying the resin in the mold. Once you position the straw over the mold you can blow very gently into the end of the straw to empty it. I have used my mouth to apply a vacuum, but this is not a good idea, and you do so at your own risk.
Step Seven: Allow the resin to cure.
Uploaded with ImageShack.us
Any resin will require a certain amount of time to cure. Alumilite's claimed demold time for Amazing casting resin is 5-15 minutes, so I allow 10 minutes. Usually it will require less, but better to be safe than sorry. This resin appears white when cured, as in the image above.
Step Eight: demold and clean up the casting
After the resin has cured, gently pull up around the corners towards the center until you have it completely removed the mold. In this case some Blue-Tac has come with it, and it will need some clean up, but afterwards it is satisfactory.
Hopefully, this will help someone or inspire someone to try resin casting to supplement the modeling techniques they already possess.
