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Post by booker on Jun 20, 2019 7:28:30 GMT -5
Hello, I just made the second half of my two peace mold I waited 14 hours. I just opened it up and the newely pour half is slightly un cured but only on the surface of the mold. I waited another 24 hours to see if it would cure more.
It did not so I've be can wiping off the uncured parts. It appears to be only on the right on the inside surface of the mold and I can wipe it off.
The mold is useable but is there something I should do to try and cure it further?.
I used 3 coats of UMR mold release.
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Post by notoes on Jun 20, 2019 9:10:36 GMT -5
You used one of the Plat series? Double check that the release doesn't have something that might inhibit the cure - the Plats are a platinum cure and can be picky. And it sounds like you waited long enough for a full cure so it most likely something inhibited the Plat. Also was your work area warm or slightly chilly? Sometimes cold and/or moisture will slow down a cure. I use Plat 25 all the time as I make custom food molds on Etsy and I never use a release agent. The only time I ever use a release agent on any of the silicones is when I'm making a two piece mold and need to pour the second half on top of the first so I would put a release agent between the two halves (silicone completely sticks to silicone if you don't).
Also what were you making a mold of? Sometimes the original item may be something that inhibits the cure too - I found out the hard way that Plat 25 does not like the Flex resin and will not cure when it comes in contact with it.
If the mold is usable, then there are a couple things you can do to it. First is what you've already done - clean off the uncured parts.
Second, you can warm the mold before using it. Heat speeds up cures especially on a Plat, I've got one of my small designs that I can pour at 8 am, put it in a very warm place, and it's cured enough to demold by 4 or 5 pm - which is very nice as this is one of my most popular designs. My other popular one is thicker so I let it go longer in the same warm room but make sure the room is very warm - between 70 and 80 degrees is good.
For a finished mold, you can warm it up in the oven or the microwave - I zap it for a minute in the microwave but if you're trying to finish the cure, I'd go 30 seconds on medium or low for a couple times (be sure to let it rest between zaps). I'm impatient so I use the microwave the most, but it can be done in the oven or on a non-food use griddle - just be sure if you use a griddle to NOT EVER use it for food.
Let us know how things work out for you.
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Post by booker on Jun 20, 2019 10:04:54 GMT -5
Hey thanks for the response I will try some heat. I've made two part molds with this stuff before with no problem. But like you said I'm sure something inhibited the curing process.
Also typically I don't use mold release either but this was indeed a two-part mold and I've used UMR mold release in the past with no issues.
The item I was casting over is made of ABS plastic and I have made two molds from this same master prior to this with no issues all using plat 55.
I'm a little nervous about using the microwave to be honest. What temperature would one set it to in the oven?
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Post by notoes on Jun 21, 2019 8:43:30 GMT -5
You're welcome, it's what we're here for. It's a normal response with the microwave, it took me a few deep breaths before I could try it the first time I did it but now I do it all the time. The oven method should be the same temperature as the griddle method which is 120 degrees. I'd give it about 2-5 minutes to start then go from there. Ah, two piece molds definitely need the release between. You can try regular old cooking spray with the Plats too, it's usually the first one I grab and probably won't have a problem with the Plats but then again I don't know for certain and I grab it mainly because I work in my kitchen and it's handy. I've used Vaseline on the Remelt and HS series before but can't remember if I've ever used it on the Plats so I can't say for certain it wouldn't do the same as the release.
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