These are just some thoughts and ideas on mold making and running foam as they have worked for me. Everyone is different and as many people as there are doing these processes, there are equally as many techniques.

The single most important thing you must understand at the outset, is that if you don't have good, well made and prepared molds your end results could look shoddy and will not render decent enough prosthetic appliances to be useful for anything other than "long" shots. Therefore it is imperative that you get the molds made the VERY BEST you can right from the start. Then using them for either foam latex or gelatin will not present any problems nor surprises.

Making molds is probably one of the most "individual" things we do as makeup artists. Everyone has a different formula and different technique - some are done very exactingly while others are done a little more haphazardly. I always just mixed the plaster into the water without measuring. That IS NOT the ideal way. You waste it and often get it too wet to be the best mix possible. Ideally, to run foam latex or gelatin, and to make well measured, accurately mixed plaster, and ultimately good, precise molds, you need some specific tools, the most of important of which is an OHAUS Triple Beam scale with tare weight or other scale of equal quality to weigh accurately or with which to measure components. The mix for plaster should be weighed - both the plaster and the water, though estimating has occurred with success. It is just more exact when weighed and renders the same results - usually - when done repeatedly. Also the components for foam latex need to be very exact, as does the approach to running it, that without a proper scale to weigh them you would just be shooting in the dark. And as well, gelatin has some additives that need to be weighed fairly exactly too if you are doing this process. Then the other tool is, of course, the mixer to create the foamed latex. I use the old standby - the Sunbeam Mixmaster Mixer. They have just come back out on the market after some absence. They usually cost around $180.00 but if you are lucky as I was, you can find one for about $88.00. I got mine at Wal Mart and it was marked down - I think because they were closing them out at that time. The OHAUS scale will be about $164.00 with the extra weight set that you might need later. You could just as easily use the Hobart mixer which is a bit more the industrial type of bakery mixer - much more heavy-duty.

So the tools are important if you plan to do this at all. Then you need lots of small things to do this, but you can pick them up as you go along and need them. There are no specific tools necessary to run the molds, with the exception perhaps of a 1/4" drill bit to drill some sprue holes (escape holes for foam spill-off), and perhaps a decent router bit (to create half-round keys in your molds - but there are other ways). Without the proper tools you might as well not pursue these processes. Without them you would be getting the work done but with less than accurate or stable results.

Now as for the plaster to use, there are numerous kinds but for all around purposes, Ultracal 30 is the plaster of choice. The only thing you might have to do is to adjust formulas for mixing due to the fact that depending upon where you get it, or how old it is, it might react differently. Dick Smith said he used to get some many years ago that was quite strong. But in recent years he has said that the plaster is much weaker (and especially on the West coast) due to the lessening quality of the gypsum being mined and other contributing factors - perhaps pollution or corrosion of some other type. But most Ultracal 30 is OK. I get mine from a U.S. Gypsum dealer and the last two 100 lb. bags I got were fine. There are many additives you can put into the plaster as you mix it that will make it anywhere from 3 - 10 times stronger when set and hardened. One I use, is a product called ACRYL 60. You might be able to find it locally much cheaper than the supply places (the Ultracal included), and when added to the plaster mix it renders a much stronger mold that will resist flaking, cracking and will stand up to many more bakings than without it. Acryl 60 is actually a cement hardener and is an acrylic emulsion which bonds with the molecules of the plaster making it much stronger than just using the plaster alone. This eliminates the need for a wirecloth, burlap or hemp reinforcement of the plaster molds. And you can make your molds a bit thinner to reduce the weight and save on plaster as well. There are other brands of concrete hardener you can get that do pretty much the same things. And it still doesn't hurt to use the hemp coat as extra reinforcement for security's sake especially if you have to bake the molds many, many times.
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First of all the water you use should be drinkable and not with too much chlorine - that can effect the setting time of the plaster. It is always better to weigh the components when mixing until you get used to eyeballing how much the formula takes in the mixing containers you decide to use. The water should be about 100 - 110 degrees. If you use colder water the plaster sets slower. If you use warmer water the plaster will set faster. So adjust as you need to for what you are doing. Sometimes you want the plaster to set faster than at other times.

The correct (and best) formula for mixing plaster to water (and/or with Acryl 60 added) is as follows: Use Acryl 60 in water (1/2 and 1/2) and mix with Ultracal - 35 parts water/Acryl mix to 100 parts gypsum (Ultracal). Basically make the Acryl 60 and water mix ahead. Use 1/2 Acryl 60 and 1/2 water mixed in a gallon jug. Usually you can adjust the water with Acryl 60. So with a 30 part Acryl/water mix instead of a 35 part Acryl/water mix you use 100 parts of Ultracal but it will still come out about the same and maybe a bit stronger still. Obviously the more acryl 60 you use to the water mix, will make it that much stronger. But there is a point at which the Acryl 60 gets foamy and leaves too many air bubbles. So you have to be cautious how much Acryl you use. The formulas above are reasonable and have been tested and used in those formulations for a long time successfully.

If you want to get real exact, use a container like a beaker or something, to measure 300 ml. (millilitres - equivalent to 300 grams) for each batch - measuring out of the gallon jug of the Acryl/water mix, one to five batches of this, at 300 ml. each (of half and half mixture) into a one gallon plastic pan. Three units of the Acryl/water mixture plus the plaster, gives half a pail of Ultracal. 5 units of the Acryl/water mixture plus the plaster gives almost a gallon of plaster. So you have to adjust to how much you need to make so you don't waste it. Measuring it out in batches of the Acryl/water mixture and then the correct amount of plaster is best because you use only what you need to use. Add in the plaster in the same number of 1,000 gram Ultracal units as you use units of Acryl/water mixture. For instance if you use three batches of Acryl/water - then use three batches of 1,000 gram units of plaster - by weight. Sift the plaster into the water till the water is absorbed by the plaster.

Let it soak for 2-3 mins. Mix with a rubber disk on a drill (attached to a long piece of all thread rod) for at least 3 minutes. Let it stand for a few minutes but stir occasionally by hand to keep plaster from settling. Pour it before the plaster creams and begins hardening.

If you are mixing only one or two units of Acryl/water mixture, put it in a smaller bucket so that it will be deep enough to mix using the rubber disk on the long all thread rod in the drill. Otherwise, you mix by hand and wear out your arm. Three minutes with the disk is worth 5 minutes by hand. Setting time of the Ultracal is either the same or a little slower with Acryl 60 in the water mix but when it no longer is workable let it set and when it goes through it's heating phase and then becomes cool again, then you can remove the retaining wall and seperate the molds, removing the clay and cleaning them up to allow them to dry for some time.
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Ideally, if you do the sculpting correctly on the life mask (or sections you are using), then the cutting edges of the overflow will be very close to the finished part of the clay sculpt. And as you feather out the sculpting of the clay onto what will be the exposed skin, it gets really thin. This way your molds, and subsequently your appliances, will have tissue thin edges that literally disappear when glued down. Anything less is a waste of time and will make the edges show too much to be believable. Then when these are cast in plaster you must be careful not to damage the cutting edges. Otherwise the appliances will reveal the problems. If you are successful in creating a good sculpt in clay, then you won't have undercut problems either and you'll have good edges for the appliances that are to be made. So I stress the need to get (first) good sculpts and then (secondly) good molds from which to run foam or gelatin.

The key to getting both is simply to take your time and be accurate with what you are doing. There is NO substitute for quality from beginning to end - in both process and materials so don't skimp on materials either. AND ABOVE ALL - KEEP NOTES. The first batch of foam you run should be a test batch and could likely be a waste anyway. Anytime you get a new foam kit you should always run a test batch to see how it reacts. EVERY batch is unique (usually) and will have it's own set of idiosyncrasies in the use of it. So I urge you to waste a batch, keep notes and then when and if you have a reasonably successful run you will know all the components in their exact measurements, the running times on the mix, the loading of molds and how that goes, the gelling time of the foam and finally the running time and end results of the baking to completion. This, then, will usually give you successful runs every time after that - but NOT ALWAYS.

This stuff is so VARIABLE that you plainly just never know. You just have to be careful and make sure all conditions are optimized for best results - including, but not limited to temperature, humidity, and your attitude. YEP!!! You heard me right. How you feel about what you are doing CAN and HAS affected the end results of running foam latex. Remember, latex is an organic substance from a living plant. And being such, there are proponents of the idea that how you feel when you run a batch of foam (i.e., anxious or whatever) can affect the outcome of running foam. I really didn't believe that much myself until I started using it and had some failures. I was anxious, in a hurry, apprehensive and generally scared to death the first few times I used it. But I finally settled down and relaxed. Basically I decided that if I wasted it no big deal - but after I calmed down, things went smoothly. That has happened and is true for so many people that I have to think there is some validity to the thought.

Anyway, once you get the molds done properly (positives and negatives) then you run the foam through the mixing, foaming, refining and gelling processes, load the molds, close them and then bake at a consistent temperature (or as much so as possible) and you end up with foam latex appliances. That temperature is generally around 175 - 200 degrees but it varies a lot from one user to the next and is very dependent upon the foam latex oven (or general use oven) used to bake the foam and the recommendations of the manufacturer.

Now I jumped past a lot of information that I will go back and fill in. I just wanted you to see that there is no magic to this process, you just need to take your time, learn how to do it once, and then you'll have it from then on, adjusting only to the different brands of foam latex out on the market which you might use and each new batch you buy. But once you have it - you have it more or less.

Let me back way up - almost to the beginning. You must get a life mask made of whomever you intend to create the prosthetics for - either yourself or someone else. Do you know how to do this process? If not you need to know. Check out the website and on the TIPS & TECHNIQUES page there is a new process on how to get a full head or front of head lifemask. With this knowledge, you create the life mask - FROM WHICH - you make smaller "sectional" molds (often called "snap" molds) of the areas you intend to have appliances cover unless you intend to create a one-piece foam latex mask - not the best way. I use alginate (same as for lifecasting) and I get the sectional areas from this full lifecast in alginate which I then cast as separate positives in plaster. I get enough area beyond the area where my sculpt will be and cast that in plaster leaving the back side of that mold kind of rough and peaked with dried plaster. This makes it bond easier later on when you immerse this cast into the circular base of more plaster (if that's the kind of mold you're doing). This circular "base" of plaster is created by using a rubber matting wall about 3" - 4" tall, securing it in a circular shape with rubber bands to fit the "sectional" mold and still leave ample overflow area as well. A new batch of plaster is mixed, poured into this rubber mat wall and the sectional mold gently laid down INTO this plaster base - being sure to not let it sink too much so you can get to the area to sculpt on or transfer your clay sectional sculpts to from the full face lifecast. The plaster is allowed to heat up (normal) and as it starts to cool, the rubber wall can be removed. Be sure you remember which of the rubber walls you use because you are going to wrap it around this same mold again later perhaps. You can smooth the mold out at this point and "clean up" any bubbles or high spots, fill any small holes created by air bubbles (be careful not to destroy texture though), etc. Then the mold has to dry fully and that is a process of several days. Or you can bake them at real low temperatures for several hours to aid in this but this isn't recommended.

When the mold is completely dry, they are ready. You will do your clay sculpting on the full face life cast in the meantime as the sectional molds are drying after some days. And then when you have it as you want it, symmetrical or otherwise, you will remove the "sections" from the full life cast and place them on the sectional molds, adjusting and getting the textures, wrinkles and edges back to normal for the appliances you are making. The reason you can begin the clay sculpture on the lifecast for whatever you are doing is because it is easier to see the "whole" picture rather than trying to sculpt individual pieces on the individual sectional molds.

There is a process that is called "floating off" the pieces to remove them to the individual plaster molds to accommodate only the sections you are creating. This is done by coating the full lifecast with Alcote (a dental mold release agent). You coat the lifecast with a few layers of this substance, let the coats dry, then do the clay sculpt over the lifecast as usual. When you are ready to remove the sculpt from the full lifecast you cut the sections apart (wherever you intend them to be split and overlapped) with a thin piece of stiff acrylic plastic sheet or a real thin bladed hobby knife - but be careful you don't dig into the cast beneath the clay. Then you soak the lifecast in a sink or tub of cold water. The pieces should simply "float off" the original lifecast when the Detachol is dissolved again in the water and you can remove them to the individual sectional casts, readjust the edges and texturing, etc. Once your sculpt is done on each sectional mold, you coat them with Vaseline (or some spray-on clear acrylic sealer spray - or cap plastic) and this seals the sculpt for casting each negative. You also have to create keys so the two mold halves, when put together, will fit exactly. This is done using the half-round router bit or some other key process you might like to use. Once this is done, you place the rubber wall around it again (maybe same one as before or a taller one) and secure it with rubber bands. Then mixing another new batch of plaster, you carefully pour the plaster in over the clay sculpt (after first applying a splash coat with a soft brush to eliminate air bubbles) and above it enough that it won't be thin in any area - usually an inch or so above the highest point on the sculpture. This is the negative mold of the sculpt, when filled with foam latex and the positive pressed into it, and will render a perfect form fitting prosthetic appliance - hopefully, if you've done it right, with tissue thin edges to blend.

Once this new mold begins to harden you can again remove the rubber retaining wall. Let it dry enough to not be moist and carefully separate the two mold halves taking GREAT care not to damage them at all. If your sculpt is correct there will be NO undercuts that might lock the two pieces together forever - save breaking it off with a hammer. Use a couple of blunt wooden sculpting tools to separate the two mold halves. Remove the clay from the two mold halves and clean thoroughly with acetone or alcohol and a semi-stiff brush. Be careful the texture isn't ruined by brushing too hard. Also make sure the mold is dry enough otherwise you will be introducing a liquid (the acetone or alcohol) that might ruin the mold by rewetting it and the plaster will break down again. These molds should be set aside and allowed to dry fully for as many days as you can - usually 4 - 7 or 8 days. I have set them outside in the sun to dry and they do harden and dry nicely at a fairly slow rate. Do that only during the days when they are first made - don't leave them outside for 7 days. Once the molds are dry you can "clean" them up again, getting rid of sharp edges, small imperfections, etc. Again you can speed up the process by baking at 125 - 150 degrees for a few hours but I don't recommend doing it that way and don't do it myself.

When the molds are fully dry and you have two casts (a positive and corresponding negative), you are ready to run the foam, fill the molds and bake them. That process is simply a matter of having the proper materials with which to work and the space to do it. If you are stuck with having to do this in the kitchen near the oven you are going to use, be sure to have all the components and tools available there to do the job beginning to end with few, if any, interruptions. Depending upon the type of foam you use, the techniques are not that much different. I will describe the process I use for the brand of foam I like. The brand I use is GM Foam. This is a product produced by Gil Mosko and is available at many of the makeup supply shops all over the country - he has certain distributors. When you decide how much you will use, you can purchase the appropriate sized kit. They come in quart, half gallon (some places), gallon and five gallon kits. Likewise, depending upon what you have cast and what you are making, that will determine how much to get. I usually get it by the gallon. If I use it up fine - if not it sits on the shelf and has to be maintained between uses (namely periodic - weekly - shaking of the bottle of foam base to keep the latex from separating from the suspension medium - ammoniated water). Anyway, the scale should be set up and ready with all your containers ready to use. The mixer should be set up as well readied to begin the foaming process. For measuring I use small one ounce and two ounce plastic medicine cups (wax coated are good too) and for the foam base I use a plastic measuring cup.

The foam latex "kits" from GM are comprised of Base, Foaming Agent, Curing Agent, and Gelling Agent. Also you get a small quantity of mold release with it. Usually there are a couple of sheets of paper that are printed with explicit instructions for how to use the product with different "schedules" to use depending upon the room conditions (which includes temperature, humidity, etc. and the size "batches" to run on). You decide what to use for the conditions under which you are working.

Get your molds lined up with the negatives lying flat on the table and the corresponding positives on edge just behind them on the table. The reason for this is when you have to start loading molds with foam latex you can't waste time looking for the corresponding half of a mold. You should even number the molds and draw a line or two across both of them (when they are resting together) to line them up properly so they fit snugly and correctly. No guess work here. Not a good thing and it wastes time. Also be certain to apply mold release (many different things you can use) so the foam won't glue the halves together when foam is poured into them and they are closed together. I use the suppllied mold release in sprue holes but for the majority of the rest of the mold I use LUX soap, lathered up and applied with a brush to the mold surfaces required to be coated. You will come up with your own mold release that you like to use all the time and will stick with the one that works the best for you.

You begin by measuring out the components and weighing them. With a scale you have to weigh the containers and then add those weights to the amount of component you are supposed to weigh out. For instance if your container weighed 50 grams and you were supposed to weigh out 150 grams of latex base, you set your scale to trip at 200 grams. This is an easy way. With an Ohaus triple beam scale with tare weight, you put the container on the scale table and whatever it weighs you cancel that back out to 0 (zero) using the tare weight adjustment, set the weights to whatever the component weight (say perhaps 150 grams) is supposed to be and then add the component to the container until the scale trips. This will be the foam base and should be the last component you measure out. The reason for this is because the ammonia that keeps the foam latex base stable will begin to evaporate too quickly and could cause the foam to gel in the bowl when you add the gelling agent. So measure the foaming agent, curing agent and gelling agents, first into small one ounce or two ounce plastic cups and set them aside ready for use. Then do the foam latex base when you are ready to begin.

The following are the components and the amounts that worked for me on the batch of foam I was using. This is known as a "1 batch". Essentially, with each kit of foam being so unique, you should adjust these amounts when you test run it and get a successful run - keeping notes as to quantities as you go. But this is what worked for me. The following:

150 grams of foam latex base
30 grams of foaming agent
15 grams of curing agent
11 grams of gelling agent

I also added back in some ammonia (I used household ammonia but ideally you should use 27% ammonia - pretty strong) because when the conditions are not ideal the ammonia can quickly evaporate out of the latex. And this causes the foam to gel too quickly - either in the bowl or too soon as you begin to try to fill the molds with it. I will explain how much as I go through this explanation. For now don't worry about how much. It will vary. With 27% ammonia you obviously have to use less since it is such a strong substance compared to household ammonia.

You begin by putting the latex base, the foaming agent and the curing agent, into the smaller mixing bowl that comes with the Sunbeam mixer and turn it on. Again this process will follow below as I explain it because each phase will have different speeds at different timings. Therefore you will need a stop watch to be certain of these phases so invest in a decent one that you can reset quickly and learn how to use it. You will have to adjust these timings as well to suit the batch of foam you get each time you get a new one. But for now, this worked for me.

Mixer speed Timing
1. Speed #1 - 1 Minute
2. Speed #7 - 3 Minutes: (This should give the foam what is known as a 6 rise or thereabouts. I'll explain.)
3. Speed #3 - 3 3/4 Minutes: Refine
4. Speed #1 - 30 Seconds: Refine
5. Speed #1 - 30 Seconds: Add GELLING AGENT (Take the full 30 seconds to do this.)
6. Speed #1 - 15 Seconds: Backturn the bowl by hand, taking care to blend in all the gelling agent with a small plastic or nylon spatula.

During this process I have added anywhere from 10 to 45 drops of household ammonia to reconstitue the ammonia in the foam. This may have been too much at times but it never hurt the end products. I could have used less but when I got it to work correctly I just stayed in that range of ammonia as closely as I thought I needed to for subsequent runs.

Stop the machine.

This is where everyone panics the first few times because you only have several minutes to get the foam into the molds (or a foam latex gun) and the molds closed. But if you work quickly and accurately then you won't have any problem. You can spoon the foam into the molds with a plastic spoon. Be careful to get the foam into all the nooks and crannies and NOT get air trapped under a spoonful of foam. The foam is VERY LIGHT at this point and can leave gaps you would miss getting it into a mold on occasion. If you do, that will leave voids on your finished pieces that you won't even know about until you demold them. Some people even brush a layer of foam into the molds at this point but I never did and it usually always worked out fine. So just be careful. If you work quickly and get all the molds filled you can put the positive molds into the foam-filled negatives at this point. I was always paranoid and I would fill several at a time, close them, and then proceed till they were all filled and closed. You might have to move the surface skin on the foam, back out of your way to get at the uncured foam underneath when you do it that way, but that isn't too big a deal. The surface foam happens rather quickly anyway but not a problem to deal with - just a slight annoyance. Try to keep the spoon free of excess foam - it is sticky and makes it harder to spoon into a mold. So get all the molds filled and upon closing any of them you push the positive into the negative until the foam seeps out of the overflow area and out of any sprue holes you have drilled into the positive to prevent back pressure. Don't be afraid to press quite firmly. If you have big molds you can even put them on the floor and stand on them for a few seconds. What this does is gets the tissue thin cutting edge really compressed so you have these tissue thin edges on the finished appliances for impossible to see blending edges. Some molds may need a mold strap to keep them tightly closed. But on the smaller ones I have done, I don't use any straps, or rubber bands or anything and I have never had a problem with thick edges. Just press the molds together well and you would be fine. It doesn't hurt to have help during this whole process so find a friend who wants to learn. Also with big molds you can close them first and strap them closed tightly.

Then you "inject" the foam into them using an injection gun, through a sprue hole (or injection hole) and when the foam seeps out of the overflow (or flash) areas the mold will be full.

Quickly, back to the business of "rise" of the foam. What you have is latex that as it foams, rises to several times higher than the original quantity in the bowl. Thus the term - rise. When foam latex rises, or the higher it gets, this indicates the cell structure of the substance has air introduced into it by the foaming process and the chemical reaction of the addition of the foaming agent. For our purposes getting anywhere from a 4 to a 6 rise in the bowl is adequate. Mine always rose to about 6 times it's original volume. Of course the closer to the top it gets the more ammonia that will escape causing the possibility of gelling too fast. But you test the rise by having a small dowel rod onto which you have marked the height equal to one cup of the foam base (just use water) and for every cup (measured in the bowl) of liquid you put into the bowl, another mark is made. Usually five or six marks is sufficient. So when it reaches the 5 or 6 rise it should indicate, then you know it has whipped enough air into it to give the beginnings of good cell structure to the finished foam when baked (along with refining the foam at lower speeds to refine the cell structure.