I'm not sure how many of you out there use Monster Makers foam latex -- for me, it's the ONLY foam I ever use and have recommended it highly over the years.... till recently.
This past week, I bought a new quart kit for a project, and discovered that the Mix Ratios had been changed "as of 2013" it said, "we strongly recommend that you use 170g of foam base instead of 150g. It will make better foam etc etc".
So, I did as it said, and 4 hours later, cracked open the mold to find a hollow skin (never gelled).
I went back over the instructions and found what I believe to be a small error in their measurements: 170g foam base, 30g foaming agent, 15g cure agent, and 10g gelling agent! -- in the old instructions, all the measurements are exactly the same save for the base, 150g, and the gel, which used to be 12g. And that's not the worst part, on the back of the form, it tells you measurements for cups and spoons (for people w/out gram scales) and they say a 1/2 teaspoon of gel -- That's 7 grams less than you ought to have. No wonder
So, I said the heck with the new mix, I'll just do it like always, with the old mix ratios -- well, that didn't work either. It gelled, but the consistency of the foam was extremely airy and loose, not nearly as fine of cells or as 'dense' as good foam should be; in all, just an unusually wrinkly, bubbly mess.
So, I'm about to try it again today. This time, I'm going to use the new mix ratios, but use 12g of gel as it probably should be. Hopefully, this will work -- I've been running foam since I was thirteen and I've never had trouble like this -- either way, I'll be sure to post the results tonight.
I have a batch of MM foam, first time I've used it, bought 2013 so it had the old instructions, 150g base and 12g gel.
I've used Burman and GM foam for years, and I never mixed it exactly according to instructions. I usually reduced the gelling agent, only a little when the latex is fresh but more as it gets older and there is more air space in the container. So the equivalent of using 10g of gel instead of 12 is pretty much what I always do. I've never used measuring spoons though, I always weigh it.
For my very first foam run with Monster Makers, I had to mix up two 200g batches of MM at the same time, with 2 mixers side by side, to fill a mould of a 1:6 scale horse. I see from my notes that I used 12g of gel in each 200g batch, rather than 12g for a 150g batch as the instructions said. It was very slow, nearly 1 hour, but did gel. I had got confused between making a double sized batch, and two smaller batches, and somehow doubled the curing and foaming agents in each batch - not surprisingly the result was a poor, coarse foam structure, and may have contributed to the slow gel. But for a horse standing in the background, tossing its head a little but not doing much else, it was still usable. I would cast again if I need a hero horse. I later cast a slightly smaller puppet (my Triclops avatar) with 300g in one batch, and the right amount of foaming and curing agent, and 22g of gel instead of 24, and I got a good result. But that is all from before the change in the instructions.
I suppose it is possible that they changed the gelling agent? I have used another gelling agent from the UK (Aquaspersions) which was more concentrated, you used about half as much gel as with the Burman or GM kits. (I had bought 20 litres of latex base locally and was buying all the components from Aquaspersions, because I had a lot of big puppets to make and that worked out half the price of the kits.) In which case, less gel would be essential. But you may well be right and they made a mistake.
I tried another run today, and adjusted the gel agent to what it should have been. Everything gelled fine, in fact, it was a close call -- I was just able to get the mold closed when it gelled -- anyway, this particular batch of foam looked perfect as it mixed up, and I thought I had a winner. But 4 hours later, the same exact problem occurred. Loose foam with huge air cells that were not present during the mixing stage. Unusable.
So now, my only thoughts are -- 1) either my mold still contains some repellent chemical leftover from my previous botched silicone cast (in which, the silicone never set and I was forced to clean everything out with naphtha). This seems rather unlikely to me, however, as I allowed the mold to air out for days and even dried it out further in the oven. There shouldn't be any trace of those chemicals left.
2) I wonder if something could be wrong with one or each of the individual foam components? Could they have gone bad? I know the foam base is still good, as it smells quite strong of ammonia. The others, like the foaming agent perhaps, I'm not sure of. It has been awful hot in my town, maybe things went sour in the warehouse?
I've used new batches with the old measurements and things have worked. So far I've only made facial appliances, nothing thick. Like LIO, I rarely use the full amount of gel simply because it kicks faster than I want.
It almost sounds like the gel wasn't mixed thoroughly. I put in a few drops of acrylic ink when I add the gel so I have a visual cue telling me when the gel is evenly mixed.
Call or email Arnold Goldman (MM owner) if you're having problems. He helped me a couple of times and I don't have failures anymore.
(The measuring spoon amounts are a crutch for people who don't have a gram scale, and while it's offered for convenience it's not recommended. It gets you close, but it's not ideal. It's tuned to the basic recipe (150g base, etc). Multiplying or dividing to get larger and smaller amounts isn't practical because it amplifies the inaccuracies.)
I use a bit of pigment with my gel too, for the same reason as Dave - it lets me know I have mixed it in thoroughly. I'll be casting a creature with the GM foam again late next week I think - still refining the sculpture so I haven't made the mould yet. I'll see how the cell structure holds up.
So, since my original post, I have tried casting 4 more times. In the first 3, all the results were unusable, see below.
I talked to the formulation guy at Monster Makers for an hour and by the end of our conversation, we both agreed that there was no reason this should be happening, and narrowed it down to a problem with the gelling agent. I asked him if it was possible that the batch was just bad, and he said that things like that had happened in the past, but he's sure that quality control was A+.
I was at the end of my quart and still no usable puppet. So I bought another kit (this time animatronic grade -- reasoning that I would end up with a different batch and prove my point). I got the stuff in the mail and found to my dismay that the lot number on the gel and cure was the same as my last batch -- figured, whatever, I'll just try it and see --
Last night I got a usable cast! -- but here's the down side, even though the puppet is usable, the foam density is still incredibly light and airy. The tensile strength is about half was it should be as well.
In comparison with an older puppet of mine, the difference is quite apparent:
OLD PUPPET --close-up.
NEW PUPPET -- close-up.
As you can see, the new texture is more like ripped up bread than smooth, fine foam.
As of now, I'm debating weather to cast yet again, and decrease my initial whip time to make it more dense. Granted, I've never had to do this before, so I'm still wondering if something's wrong, or if they've just changed their formulation.