Degassing when Casting

[army310]

do you have to degas when casting or is it a nice thing to do? Because I'm going to start casting very small guys and arms that are about .01 cm at the smallest.
the resin that I'm using is
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... K:MEWNX:IT
and the silicone is
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... K:MEWNX:IT

Are these good enough for what I'm trying to use them for?
Pm me if you wan to know what I'm trying to do.

As always Thanks for the help:)

[mangozac]

Degassing when casting isn't necessary, but if you have a vacuum pump then it can make life easier as you don't have to be as stringent with appropriate air channels. It's not quite the same as basic degassing of the resin - you're applying vacuum while the resin is in the mould, helping to suck air out of the major cavities. It's still desirable to apply pressure before the resin sets.

For doing really fine stuff like you mention I personally wouldn't want to try it without the vacuum stage, but it all depends on the resin, particularly on factors not listed in the data in that auction link.

Hang on: the first link is to a polyurethane rubber. Is that resin or are they just using screwy terminology?

[Munkey Joe]

I use that company... but I do think that "rubber" is actually a solid rubber. If you look to the description it says something about tires, engine mounts and stuff with a shore of 75. 75 is like skateboard wheels, car lifting kits, PVC, and...well motor mounts. Its pretty tough stuff but not the super hard, brittle FW resin. It might just be a play on words.... dunno.

Also if you order from the actual website you might save money. John is a great guy (he actually answers the phone!!) and if you call him he can tell you the products he has to match your needs. his site is : and his phone is on the site.

As for the question... Im degassing in another container and making molds under pressure. when I pour my plan is to have vents and such until I get a "real" vacuum. If your willing to share I am willing to put any input I can into your project. feel free to PM me your project if you wish.

Mangozac and Pig....you were right..... suction is rubbish for this. i have to degas in a jar separate and its all it can do with that...

[blind pig]

I vacuum degas silicone before pouring into moulds, then allow the moulds to cure under pressure (usually 80PSI).

I don't vacuum degas polyurethane resin before pouring (humidity and pot life stop this from being effective), but do cure the polyurethane in the mould under pressure (usually 60PSI).

I don't cure resin in a mould under vacuum. The stuff I do usually isn't fiddly or fine, but if you look at Forgeworlds stuff, then a lot of their casting is done under vacuum.