To bake foam latex, you need an oven that you do not cook food in, that will go as low as 160 degrees Fahrenheit. It must also be able to fit your molds into the oven, which is why we built a huge one, to fit our body mold in there. You also definitely need a scale that measures in grams.
You want at least one extra person to help with foam latex if you have molds larger than a foot or hand mold. We needed six people for the body mold, because it’s very time sensitive.
You’ll need a foam latex kit, there are several bottles that come with this that you’ll need, and a mixer (we had a 5 quart Sunbeam mixer). We bought a 5 gallon kit of foam latex, and still have some left over for maybe another body suit or two, but we wanted to make sure we did not run out, and had extra to learn with. We got ours from Frends Beauty Supply.
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Here is a video we made explaining how we mixed our foam latex. It’s one of those things that is a lot easier to see than to just read about. Here are some notes I have on mixing foam latex:
Molds should be dried out before you bake foam latex in them. Bake stone molds clamped together with their core in the oven at 180 F for twelve hours, and fiberglass molds bolted together with their core in the oven at 160 F for twelve hours.
Bake stone molds at 180 F. An easy way to figure out how long to cook your foam latex, is to add the thickness of the thickest part of the sculpt and thickets part of negative plus thickets part of core divided by 1 inch = hours to cook plus half an hour. We baked our stone foot molds for four hours, Mario says another way of figuring out how long is about 2 hours per inch of thickness of the foam. It takes some practicing to get the hang of it.
Fiberglass molds are baked at 160 F, we baked our gloves for 4 hours and the body mold for 8 hours.
Always make sure that your oven is convection and has airflow to keep the temperature constant and even. If you are not able to get a convection oven, make sure to rotate the molds every hour, but as quickly as possible, because you lose heat quickly when you open the oven.
Having a run schedule printed out is important, GM foam has run schedules you can work off of. Also, we made a worksheet that we could fill out as we worked on the foam latex to make sure that the results are always the same, and helps you remember what temperature and how long you cooked your molds for.
Use a rubber spatula to help get the foam latex out of the bowl. Later, the foam latex will easily pull off of the spatula.
Make sure you place your bowl on the scale as you measure your ingredients in, and DO NOT put in the gelling agent yet! The gelling agent is added either at the time in the schedule (though the website and many artists say don’t be a slave to the schedule!), or by smell, which we did, we waited until the speed was right and we were about at the right time for the gelling agent, then began to smell the foam latex, and when the ammonia smell was very faint, we added it. You will know when it’s faint, because the ammonia smell is very, very strong when you first start.
When you add your gelling agent, pour it slowly in a thin stream into the mix near the beaters.
ALWAYS RELEASE your molds!! We used the GM Foam release for the stone molds (brush it into the mold, making sure it’s in every part of the mold, let it dry, and brush out excess) and used wax that we rubbed on and buffed off for the fiberglass molds.
Make sure there is enough room in your mixer when you put in your ingredients for the foam to rise, it will rise at least 4 times while it’s mixing.
When the foam latex is done mixing and it’s time to fill your molds, fill one side of the negative first, add core, then fill the other side and close. If there is a lot of detail in your negative mold, brush in detail with a chip brush.
Some extras we got for our foam latex that definitely helps the process are flow increaser (makes it easier to pour) and foam stabilizer (lets you build a better foam, helps keep the foam from gelling too quickly). Both are very important, as well as cell choke (keeps it from over foaming, the cells of the foam will be smaller and results in a more velvet like texture in the foam).These all help to make the foam flow better, and not gel too soon. Mixing foam latex definitely takes time to learn it; most people say you’ll waste your first batch of foam learning to mix it, because it also depends greatly on the temperature and humidity where you are. The run schedules I linked before cover the differences for those.
We did not use flow increaser for the feet, but we did use it for the hands, head, and body. For the head, we used 13g flow increaser per 150g foam latex base. A usual batch of foam latex is in increments of 150g. For the body we used 5g per 150g of foam latex base. We highly suggest using a zentai suit as a base on your body core for your body suit, to help strengthen it and guarantee that it will not tear.
If you’re making a huge body mold, you’ll need at least a 20 quart mixer, depending on the size of the mold. We figured this out by saving our clay we took off of the sculpt after we molded it, and measuring it. We rented one from a kitchen supply store.
We baked our foam latex onto a zentai suit that was put onto the body shaped core prior to mixing the foam latex. You’ll also need a lot of friends; mix up the foam latex, then quickly pour half in each mold, have two people on each one with a chip brush getting all the foam latex into all the detail, and two people getting foam latex over the core that goes in the middle. Do all of this as quickly as possible, as you may have less than five minutes working time. Quickly put the core in one side, flip over and put on the other side, and clamp all the sides shut so that everyone can start screwing in the nuts and bolts. Once that’s done, it can sit until the foam gels, then into the oven it goes!
Ok, after your foam latex is all baked, you need to open the mold, but first the molds need to cool down. It’s best to let the mold cool in the oven, just turn off the oven and when the oven is at 110-120 F, pull the mold as long as it’s warm to the touch, but not too hot to touch. Pretty much as soon as it’s cool enough to pick up and hold, take it out, but that’s usually about 120 F.
Now, get ready with the screwdrivers, popsicle sticks and baby powder. If there are bolts in your mold, take them all out. (Always make sure to store your molds closed tight though, after you’ve taken the foam latex out of them and cleaned them!)
Slowly move your way around the mold, very gently breaking any flashing that is trying to stick to both sides along the way. Put popsicle sticks into the mold as you go around, until it kind of loosens itself and the whole flange is loose. Now you need to very, very slowly pull up the top part of the mold, dusting any exposed foam latex with talcum powder or baby powder to prevent anything from sticking to itself. Continue pulling up the mold and gently pulling the foam latex from the mold while coating everything with powder, until it is all free!
To release the bottom part of the mold from the core and the body suit, we just kept pulling up on the core mold at the neck, arm, and leg ends, always adding in more powder and gently releasing any foam that’s trying to stick to the mold with our hands.
And then your foam latex piece is out! Yay! If you’re doing a body suit, it’s actually suggested to leave the body suit on the core body until it’s completely dry (it may be moist, because of the size of the mold, this is normal) and until it’s painted. I took it off before it was painted, because I needed to do some modifications to the arms, but it was very hard to get off and on the core body mold, we had to cut the arms off of the mold, it was very stressful.
There you go! Now we have a foam latex piece, next post will be on how to seam and paint it!