Release agent question

Home enthusiasts discuss their Foundry & Casting work.

Moderator: Harold_V

jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Release agent question

Post by jscarmozza »

I would like to make a core using sodium silicate and harden it in the core box to pick up some fine details, can anyone recommend a release agent?
Thanks, John
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Release agent question

Post by Harold_V »

Hmmm.

Keeping in mind I have no experience with what I'll propose, is it possible that you could use silicone spray in the mold before ramming the sand? Seems that would discourage the resulting core from sticking.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
User avatar
ChipsAhoy
Posts: 319
Joined: Wed Feb 18, 2015 12:23 pm
Location: Arizona

Re: Release agent question

Post by ChipsAhoy »

We use CRC silicone spray in our core box to release sodium silicate and sand core hardened with CO2. Our core box and patterns are 3D printed with 175 filament.
IMG_20190117_120809_1.jpg
IMG_20190121_103914.jpg
IMG_20190124_121519.jpg
IMG_20190121_120324.jpg
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza »

Thanks guys, I'll give that a try.
John

P.s. Nice work Chips!
User avatar
ChipsAhoy
Posts: 319
Joined: Wed Feb 18, 2015 12:23 pm
Location: Arizona

Re: Release agent question

Post by ChipsAhoy »

Wish I could take credit for it, but I am a student in this group, so I do help a bit. This is part of the castings for a hit & miss engine.
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza »

I still make my patters the old fashion way, out of wood. I'm amazed at the power of the 3 D printer, but I just don't want to make the investment in time and money to learn CAD and purchase the all equipment, besides, this is my hobby, if I was doing it as a business it would be a different story. That being said, you have some really nice patterns and cores, stay with it and learn how. Keep up the good work.
John
User avatar
ChipsAhoy
Posts: 319
Joined: Wed Feb 18, 2015 12:23 pm
Location: Arizona

Re: Release agent question

Post by ChipsAhoy »

If you use it, let us know how the silicone spray works with your wooden core boxes.
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Release agent question

Post by Harold_V »

While not the topic at hand, I have not great memories of the time I made a pattern and finished it with shellac. The foundry that did the casting used the Furan process, which fused the mold to the pattern. You're wise to be concerned for that reason.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza »

I'm not familiar with the Furan process, can you explain it Harold...reason being, I still use shellac to finish my patterns.
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Release agent question

Post by Harold_V »

Furan is one of the chemical processes that result in a hard mold. Like hardening with CO2 and sodium silicate, the mold is far more rugged than green sand.
While I am aware of the Furan process, I know little about it. I do know that considerable equipment is required for its use. It is reconstituted after use and used repeatedly. It's likely well beyond the ability of the home foundry.

I used shellac on the form I used to pour my tilting reverberatory, and that was a mistake, too. Had I greased it, maybe it would have been fine, but it, too, fused to the refractory. I damaged the furnace trying to get it out and ended up burning it out. A sad day for me, to say the least. Here's a picture of the form, and the resulting furnace, which was used in my precious metal refinery.
Tilt furnace #3.jpg
The furnace was cast with a low temperature external liner (using the galvanized form), then the interior liner was placed, using the wooden form. The interior liner was 94% alumina. This furnace had to withstand excessive fluxing on a continual basis, as it was used to recover values from waste materials. It operated for hours on end, and worked like a champ!

H
Wise people talk because they have something to say. Fools talk because they have to say something.
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza »

It took me this long to finish the pattern that I wanted to make. The silicone spray seems to work as a release agent, but my core broke up as I was removing it from the mold, I gave the back of the mold a sharp rap and the core busted all to hell. After gassing the sodium silicate/sand mix I noticed it was very cold, so I'm letting it warm up to room temperature before I try to remove the core. I'm using a 5% by weight sodium silicate to sand ratio, I'll let you know how this try turns out.
jscarmozza
Posts: 599
Joined: Mon Mar 03, 2014 5:09 pm

Re: Release agent question

Post by jscarmozza »

It didn't turn out very well.
Attachments
image.jpeg
Post Reply