RTV Silicon "tweaking" (1 Viewer)

C

Captkronos

Specialist
Joined
Dec 29, 2009
Messages
342
Okay, I've had a few major disappointments in the mold-making department, and reps at the place where I buy my silicon keep telling me I can't pour lead in a silicon that is made for low-melt metals, which of course I completely ignore. Anyway, the higher temp stuff has not worked well because it is so brittle it seems to break every time I do a new figure, so I'm going to try mixing in some iron oxide powder into the low temp silicon to build better heat resistance and prolong the mold life. I'll report back. I just ordered all the goods today for a small test mold. Could be history in the making...not all history is good of course.
 
Both Dupont and BJB Enterprises sell RTV silicones that work just fine for casting white metal alloys, (lead/tin/antimony). I cast in the 700F to 900F range. If you order from BJB, ask for TC-5050.

Good luck,

Ron
 
Great, Thanks! I've been throwing my money at Smooth-on for a few years, their stuff is geared more toward resin and special effects stuff. If you have a website for either, that would be great, if not, I'll hunt 'em down. Awesome, lead is SOOOOOO much cheaper than the tin/bismuth I normally buy.
 
BJB is at www.bjbenterprises.com and their phone number is 714-734-8450. If you are trying to cast pure lead, you're going to run into some real problems with the quality of your castings. The simplest solution is to buy linotype or a linotype composition and mix it 50/50 with your lead. This will give you just enough tin and antimony for good flow and detail, while staying in a low price range.
 
beaker said:
Issue is that the silicone you mentioned has a heat threshold of 300C. The melting point of lead is 327C so your rubber will not last all that long under those conditions
Click to expand...

You're right that RTV3120 is not suitable for pure lead. But I had thot that CapKronos was moving towards lead/tmixture which is optimal around 180-200oC.
 
Thanks guys, I'm going to try my usual stuff with some iron oxide powder mixed in, just because it is a 1:1 mix by volume, no scale needed. If it doesn't work, I like the looks of that BJB stuff. I've bookmarked the product pages for all the stuff you guys mentioned, should give me plenty of options.
 
Thanks Victor, I feel growing up in the '70's and snacking on all those yummy paint chips has helped prepare me for this endeavor. :) Still waiting on the silicon, the oxide I have is red powder. I've used an RTV before with a high iron oxide content, so I'm going to "roll my own" so to speak. I'll take the usual precautions (okay, I might actually wear a mask for once instead of pulling the t-shirt over my face). Stay tuned. If you hear a news report of a Midwestern man who blew himself up trying to make a bomb, only you here will know the truth...it was for "the little people"...54mm to be exact.
 
Okay, brave souls, the grand experiment has been conducted, and I pronounce success! Actually, I've only poured tin in the RTV silicon with self-added iron oxide powder, but worked like a charm. The resulting mold seems to retain much more of the elongation properties than the ready made stuff with iron oxide in it (which means I can get away with more undercuts and not breaking my mold). I'm kind of "eyeballing" it, but I used like one rounded tsp of powder in a mold of a 54mm figure. I'll try to put a pic up on the Photobucket site when I get a chance. Even if it only slightly extends my mold life, it will be worth it as I got a 3lb tub for around $10 with shipping. As you may recall, I am using a 50/50 by volume RTV silicon so I don't have to mess with a scale.
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Community platform by XenForo® © 2010-2024 XenForo Ltd.
Back
Top