M-2 RTV Curing |
| I have a slightly odd problem. I have been attempting to make 2 part molds with M-2 RTV Silicone. I am boxing the part in, using regular modeling clay to provide something to sink the part into.
My issue is that the M2 seems to be curing selectively- the whole thing hardens up great, except on the clay surface, where even after 24 hrs it looks like I just poured it.
It is very well mixed, and degassed properly prior to pour. I can even pull it out of the mixing cup in one piece (after a day). It just won't seem to cure on the clay.
Should I use a different substance than clay? Or is there something I'm not considering?
Question #2 I am using the Alumilite 610 Foam to make a foam block for lightening up a plastic piece I'm going to cast. It is roughly 8x1x1, fairly thin and long.
When I pour the foam in (about 10 ml) it only grows to about 40 ml , rather than 100 ml it should be at? It is 70 ish, maybe a little cooler where I'm mixing, could temperature be a problem? Thank you |
Posted by Jeremy D. at 03:08:07 PM on Jul 22, 2010 |
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| Probably the wrong type of clay. There is something in some of the model clays (sulfer? maybe) that in inhibits curing. |
| Posted by Dan W. at 12:27:29 PM on Jul 26, 2010 |
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| #1 - very likely the wrong Clay like Dan mentioned. Your clay object could be completely sealed with a spray paint then UMR and it may work, but always use the Alumilite Sulfer-free clay. #2 - The older the foam is or longer it has been open, the less it expands, for each pour I have to increase the original volume to allow for this. Also, immedately after pouring, rotate the entire casting to coat everything-all sides, and I found that the mold must be very warm, 120º+. -- Glen |
| Posted by Glen P. at 08:19:22 AM on Jul 27, 2010 |
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| Jeremy,
Dan and Glen are both right. I would say that your clay has sulfur or oil in it. M-2 is a platnium cure silicone and is touchy sometimes to work with. It does not like sulphur, oils (which are found in many clays), even glue from duct tape will inhibit it's cure. Platnium silicones inhibit pretty easy to where tin cures will cure against dirt.
My Best,
Carol
800-447-9344 |
| Posted by Carol W. at 08:06:02 AM on Jul 28, 2010 |
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| Jeremy,
On question #2, the foam will expand 6-10 times it's original mass. I have been told by a customer who wanted more epansion a drop of water in the foam gave him a lot more expansion. That is because urethanes are highly moisture sensitive and you will have more expansion if this is something you wanted to experiment with.
My Best,
Carol |
| Posted by Carol W. at 08:10:08 AM on Jul 28, 2010 |
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