Green sand washes

Home enthusiasts discuss their Foundry & Casting work.

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jscarmozza
Posts: 183
Joined: Mon Mar 03, 2014 5:09 pm

Green sand washes

Postby jscarmozza » Sun Aug 06, 2017 7:47 am

I'm always looking for a better finish on my castings, has anyone had any success using washes on their green sand molds? I was thinking about trying a graphite concoction on my next pour; any thoughts, advice, opinions? Thanks, John

RONALD
Posts: 474
Joined: Sun Oct 26, 2003 7:27 am

Re: Green sand washes

Postby RONALD » Tue Aug 08, 2017 7:38 am

Most of us experiment, and I see no reason why a graphite wash should not be applied, unless it damages the surface. There are various foundry supply companies that sell washes, but the quantity may be too much for you. The last time I molded with green sand was in the 70's, I have been using PetroBond and now PetroBond II since. My sand has an AFS number 105, you did not tell us how course your sand was, that would make a big difference.

PetroBond once prepared stays ready to go for many moons, we just molded four #8 Switch Frogs, out of sand from our previous pour last fall and I did not even mull it again.

Then guys over at the Alloy Avenue site may offer more advice.

jscarmozza
Posts: 183
Joined: Mon Mar 03, 2014 5:09 pm

Re: Green sand washes

Postby jscarmozza » Tue Aug 08, 2017 7:59 am

Ronald, you're forcing me to face the ugly truth...there's no fix for crappy sand. Rather than fooling around with washes, I think I should start making new molding sand. I have some PetroBond that I use as facing sand from time to time when I need a good finish, but I don't have a local source and shipping gets expensive. I cast a few #6 frogs using cores, they turned out very well (photo attached). John
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RONALD
Posts: 474
Joined: Sun Oct 26, 2003 7:27 am

Re: Green sand washes

Postby RONALD » Thu Aug 10, 2017 7:21 am

I like to see others hobbyist's castings, and yours certainly looks great.

I use C99700, a bronze called White Tombasil, for switch frogs.

I have four ready to pour, but need to make up some rail joiner flasks also in-order to justify firing up and melting metal.

In the photo is the wooden pattern and casting for a #8 frog, I also did four #10's, but that's all I intend to use.

My ratio of casting to gating, etc., is way off but luckily I do not have to worry about a "Bottom Line" for my foundry work.

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jscarmozza
Posts: 183
Joined: Mon Mar 03, 2014 5:09 pm

Re: Green sand washes

Postby jscarmozza » Thu Aug 10, 2017 6:32 pm

Nice pattern Ronald, your casting is first class too. Is the frog 1-1/2" or 1" scale? My frog is 1" scale and cast in aluminum, same material as my track. John

RONALD
Posts: 474
Joined: Sun Oct 26, 2003 7:27 am

Re: Green sand washes

Postby RONALD » Fri Aug 11, 2017 1:27 pm

We try to make everything to 1.6 scale which of course is 7.5" gauge track.

Below is my typical #8 switch using "AAR 16' - 6" Points", they are the same for the #10 switch.

There are 21 castings in the switch: 14 Rail Braces from Lost Wax. 4 for the switch throw bar from Lost Wax. Frog from maple pattern in Petro Bond sand. 2 Guard Rails in Lost Foam in Petro Bond sand. The rail is steel.


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jscarmozza
Posts: 183
Joined: Mon Mar 03, 2014 5:09 pm

Re: Green sand washes

Postby jscarmozza » Sat Aug 12, 2017 8:15 am

You have a first class operation Ronald, like yourself, I enjoy seeing what others in the hobby are doing and how they're doing it.
Thanks, John

jscarmozza
Posts: 183
Joined: Mon Mar 03, 2014 5:09 pm

Re: Green sand washes

Postby jscarmozza » Mon Aug 14, 2017 8:12 am

I poured my castings yesterday, a couple that I needed for a project and a few experimental ones. I made up about 100 lbs of new sand which I screened through my wife's flour sifter, and it worked fine providing a sand cast finish. However, since the 100 lbs wasn't enough sand to make all of the molds, I used some old sand which I also screened through the flour sifter. First of all it's hard to get green sand through a fine screen, but what I noticed was my old sand was made up of very small balls of sand and clay that went through my riddle with no problem, but wouldn't go through the sifter unless you squished them through with your fingers. Once that was done the mold and casting had a beautiful finish, even better than the new sand! The sand/clay balls were very small and went unnoticed by me until the other day. Even though I mull my sand after each use, I guess these little balls form and need to be broken up from time to time, at least for facing sand; otherwise it's like pouring into a mold surface made of marbles and the finish is bad. Live and learn.


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