Post by Asphalt on May 21, 2010 10:42:17 GMT -5
Project Shrinky-Dink
At the request and commission of GiJoey and Drbindy, I took on the challenge of reducing some classic era 1:6 and 1:8 scale figure heads to the now standard 1:18 Joe body.
Here is what they sent me,
And the body parings they are looking for.
So the first step is to get the heads ready to mold. Due to the size of the heads only three would fit in a box small enough to go into my pressure pot.
As I expect these to be fairly hard to remove from the mold anyway I filled the notches on the backs of the necks. Since the entire neck post will be removed before the second molding anyway it won’t matter much in the long run.
The mold box was then built around the heads.
And rubber was poured and allowed to cure under pressure overnight. This box is enormous. There is just under 700 grams of silicone in this single mold box. An average mold for 6-8 heads contains about 150 grams of silicone.
The box walls are then removed, revealing the pieces within the now solid mold.
The heads are then cut free using the blade of an Exacto knife. Care must be taken to not cut into the originals.
Once the heads have been removed from the mold the mold goes into the toaster oven for 2 hours for a post cure. This helps to evaporate off any residual alcohol present in the mold.
After the mold has cooled, a test cast is poured. The material used as a reducing agent is rather expensive and has a very short shelf life once opened so you need to make sure you have a viable mold with no defects before you attempt the first reduction. It is very important that your mold is cool before you pour resin, especially if there are thin crevices or dramatic undercuts. Heat greatly increases the curing speed. Pouring resin into a hot mold with make it begin to gel almost immediately, making a clean cast very hard to obtain.
Before you can start mixing resin you need a rough estimate of about how much you will need. Compared to the size of my 30cc measuring cup it looks like each head will need at least 45cc. Precise measurement of the resin and silicone is essential or your materials will not cure properly.
Now to measure, mix, and dye the resin. My resin has a natural color of just off optically clear. Since I am casting heads I will tint it to be a flesh tone. It photographs much more easily than white or clear and a natural color makes it easier to see details in the cast.
Here is my resin measured out and tinted. When casting, always have a few extra molds ready just in case you have extra resin.
And now we are ready to lock them down and cure under pressure for about 3 hours. I will probably wait longer due to the size of these pieces and the difficulty of their de-molding. I wouldn’t want to pull any of the little bits off.
And here is the Viability Check. As you can see, the molding was successful, the pieces didn’t slip in the mold, and there were no air bubbles caught in the silicone.
Because the Shrinking medium has such a short there are a couple more sets of heads I want to get molded up and ready to go before beginning the shrink process. This is the first, four Stargate 7 inch figure heads and the final vintage head from Gijoey and drbindy.
After completing a Viability run of the second mold, I found that while the Stargate heads cast perfectly,
The Big Jim Head did not. I wasn’t thinking about the head being hollow. Every other piece I have molded has been solid plastic or rubber. The big Jim head is a hollow flexible rubber. So when put under pressure for molding it was forced inward. It still cast with perfect detail, unfortunately half of the detail is concave instead of convex.
While interesting, not exactly what I was going for. I will need to speak with GiJoey and see if he would approve of me cutting open and filling the head to make it a solid construct.
After Consulting GiJoey it was decided that since the head would never be put back on a 1:6 body and was purchased specifically to be shrunk he was fine with it being filled.
Here is the problem, a completely hollow, soft rubber head. It originally had a plug in the bottom leading me to believe it was solid like the others.
You can also see the silicone that was forced past the plug up into the head during molding.
And here is the solution. I have completely filled the hollow head with resin. When it sets it will be a rock solid head like the others. In case you are wondering, no it will obviously not be cured under pressure. If you look at his neck you can see why casts and molds are pressure cured. All of those bubbles visible in the resin would remain. When the silicone or resin are cured under pressure the small air bubbles are crushed, diffusing the air out of the casting/molding material.
Here are the final two molds I am going to make for this initial experiment. With several different scale heads and even some accessories this will give me a good experimental group to see how different sized pieces react during shrinking.
Ok now I am beginning to think the Big Jim head is cursed. I ran a test cast of the of the two molds today. The mold of the two sigmas and accessories came out 100% spot on, all viable molds.
The mold of the three sigmas and the Big Jim came out 50/50. The spirit and Stone heads, no issues. The other sigma and the big jim distorted. The Long range (I think can’t remember his name) head has a caved in cheek, and the Big Jim have a dent and swirl in the hair on his forehead.
Well, GiJoey is ok with the bad hair day on Big Jim. We “are customizers after all.” So on the next step, shrinking.
The product I will be using is “Reducit II,” It is similar to Hydroshrink but is more readily available so that is what I used.
It has a 1 to 2 mix ratio.
There is no mention of the color reaction caused by mixing, so I was not sure what color to expect. Milky white it is. It appeared that it had started to congeal immediately, but I was mistaken. It was still thin as water when I poured the two molds.
Looks like I guessed just right on the volume I would need.
The first set of casts are out of the molds.
Now comes a secondary experiment. I will run at least two sets of each mold, one set will go into a Ronco Food Dehydrator and the other will sit in the open air. With the NC humidity I am not sure how quickly these will dehydrate. The Reducit material is very strange in consistency. It is very soft and rubbery. The pistol tore during removal, but I will glue it together when it has shrunk. The visor was a complete loss. I will be more careful with the second cast.
The first rounds of casts have now been out overnight and there is visible shrinkage. You can see with the small accessories and the thinner parts on the heads that the Reducit II will become translucent as it dries and shrinks.
The size comparison is with a set of casts that have not yet begun to dry out. This second run will be placed into a food dehydrator. I want to compare how they shrink in the two different environments.
Obviously it will shrink them more quickly. But I want to know if it causes any distortion that the slower process does not.
Based on the condition of the accessories and sigmas it would appear that three hours in the dehydrator is roughly equivalent to 24 in the natural air, 1 to 8 hourly ratio.
If this continues at the same rate for the remainder of the shrink the second set of heads will be a week ahead of the first batch by tomorrow morning. With NC relative humidity currently at 95% this is not surprising.
Another batch ready to start dehydrating. I won’t be putting the Stargate heads in the dehydrator as I think I may need to mold them before they finish shrinking completely.
Had some dreadlock issues.
OK here are the accessories and Jim head I put in yesterday. Very happy with the size of the weapons. That tiny little dot beside the Dread head is Tanks helmet.
And here is the comparison of two days in the air compared to one day in the dehydrator. No distortion evident in the dehydrator pieces.
As you can see the 1:6 heads still have a LONG way to go. But the sigmas are almost there.
At the request and commission of GiJoey and Drbindy, I took on the challenge of reducing some classic era 1:6 and 1:8 scale figure heads to the now standard 1:18 Joe body.
Here is what they sent me,
And the body parings they are looking for.
So the first step is to get the heads ready to mold. Due to the size of the heads only three would fit in a box small enough to go into my pressure pot.
As I expect these to be fairly hard to remove from the mold anyway I filled the notches on the backs of the necks. Since the entire neck post will be removed before the second molding anyway it won’t matter much in the long run.
The mold box was then built around the heads.
And rubber was poured and allowed to cure under pressure overnight. This box is enormous. There is just under 700 grams of silicone in this single mold box. An average mold for 6-8 heads contains about 150 grams of silicone.
The box walls are then removed, revealing the pieces within the now solid mold.
The heads are then cut free using the blade of an Exacto knife. Care must be taken to not cut into the originals.
Once the heads have been removed from the mold the mold goes into the toaster oven for 2 hours for a post cure. This helps to evaporate off any residual alcohol present in the mold.
After the mold has cooled, a test cast is poured. The material used as a reducing agent is rather expensive and has a very short shelf life once opened so you need to make sure you have a viable mold with no defects before you attempt the first reduction. It is very important that your mold is cool before you pour resin, especially if there are thin crevices or dramatic undercuts. Heat greatly increases the curing speed. Pouring resin into a hot mold with make it begin to gel almost immediately, making a clean cast very hard to obtain.
Before you can start mixing resin you need a rough estimate of about how much you will need. Compared to the size of my 30cc measuring cup it looks like each head will need at least 45cc. Precise measurement of the resin and silicone is essential or your materials will not cure properly.
Now to measure, mix, and dye the resin. My resin has a natural color of just off optically clear. Since I am casting heads I will tint it to be a flesh tone. It photographs much more easily than white or clear and a natural color makes it easier to see details in the cast.
Here is my resin measured out and tinted. When casting, always have a few extra molds ready just in case you have extra resin.
And now we are ready to lock them down and cure under pressure for about 3 hours. I will probably wait longer due to the size of these pieces and the difficulty of their de-molding. I wouldn’t want to pull any of the little bits off.
And here is the Viability Check. As you can see, the molding was successful, the pieces didn’t slip in the mold, and there were no air bubbles caught in the silicone.
Because the Shrinking medium has such a short there are a couple more sets of heads I want to get molded up and ready to go before beginning the shrink process. This is the first, four Stargate 7 inch figure heads and the final vintage head from Gijoey and drbindy.
After completing a Viability run of the second mold, I found that while the Stargate heads cast perfectly,
The Big Jim Head did not. I wasn’t thinking about the head being hollow. Every other piece I have molded has been solid plastic or rubber. The big Jim head is a hollow flexible rubber. So when put under pressure for molding it was forced inward. It still cast with perfect detail, unfortunately half of the detail is concave instead of convex.
While interesting, not exactly what I was going for. I will need to speak with GiJoey and see if he would approve of me cutting open and filling the head to make it a solid construct.
After Consulting GiJoey it was decided that since the head would never be put back on a 1:6 body and was purchased specifically to be shrunk he was fine with it being filled.
Here is the problem, a completely hollow, soft rubber head. It originally had a plug in the bottom leading me to believe it was solid like the others.
You can also see the silicone that was forced past the plug up into the head during molding.
And here is the solution. I have completely filled the hollow head with resin. When it sets it will be a rock solid head like the others. In case you are wondering, no it will obviously not be cured under pressure. If you look at his neck you can see why casts and molds are pressure cured. All of those bubbles visible in the resin would remain. When the silicone or resin are cured under pressure the small air bubbles are crushed, diffusing the air out of the casting/molding material.
Here are the final two molds I am going to make for this initial experiment. With several different scale heads and even some accessories this will give me a good experimental group to see how different sized pieces react during shrinking.
Ok now I am beginning to think the Big Jim head is cursed. I ran a test cast of the of the two molds today. The mold of the two sigmas and accessories came out 100% spot on, all viable molds.
The mold of the three sigmas and the Big Jim came out 50/50. The spirit and Stone heads, no issues. The other sigma and the big jim distorted. The Long range (I think can’t remember his name) head has a caved in cheek, and the Big Jim have a dent and swirl in the hair on his forehead.
Well, GiJoey is ok with the bad hair day on Big Jim. We “are customizers after all.” So on the next step, shrinking.
The product I will be using is “Reducit II,” It is similar to Hydroshrink but is more readily available so that is what I used.
It has a 1 to 2 mix ratio.
There is no mention of the color reaction caused by mixing, so I was not sure what color to expect. Milky white it is. It appeared that it had started to congeal immediately, but I was mistaken. It was still thin as water when I poured the two molds.
Looks like I guessed just right on the volume I would need.
The first set of casts are out of the molds.
Now comes a secondary experiment. I will run at least two sets of each mold, one set will go into a Ronco Food Dehydrator and the other will sit in the open air. With the NC humidity I am not sure how quickly these will dehydrate. The Reducit material is very strange in consistency. It is very soft and rubbery. The pistol tore during removal, but I will glue it together when it has shrunk. The visor was a complete loss. I will be more careful with the second cast.
The first rounds of casts have now been out overnight and there is visible shrinkage. You can see with the small accessories and the thinner parts on the heads that the Reducit II will become translucent as it dries and shrinks.
The size comparison is with a set of casts that have not yet begun to dry out. This second run will be placed into a food dehydrator. I want to compare how they shrink in the two different environments.
Obviously it will shrink them more quickly. But I want to know if it causes any distortion that the slower process does not.
Based on the condition of the accessories and sigmas it would appear that three hours in the dehydrator is roughly equivalent to 24 in the natural air, 1 to 8 hourly ratio.
If this continues at the same rate for the remainder of the shrink the second set of heads will be a week ahead of the first batch by tomorrow morning. With NC relative humidity currently at 95% this is not surprising.
Another batch ready to start dehydrating. I won’t be putting the Stargate heads in the dehydrator as I think I may need to mold them before they finish shrinking completely.
Had some dreadlock issues.
OK here are the accessories and Jim head I put in yesterday. Very happy with the size of the weapons. That tiny little dot beside the Dread head is Tanks helmet.
And here is the comparison of two days in the air compared to one day in the dehydrator. No distortion evident in the dehydrator pieces.
As you can see the 1:6 heads still have a LONG way to go. But the sigmas are almost there.