MHester

My Feedback: (1)

pardon me for the stupid question.

I have been using the Fiberglast white surface coat for my molds, and have been failry pleased with the results. However, I don't like the white color, and when I add graphite, it just turns grey. If I add enough to turn it black, I get nervous because it gets REALLY thick and changes properties.

So, how do you guys get that nice, hard black surface coat? Same way I'm doing it, just more graphite? Or something else? I'm going to make a really high use set of molds, to be suitable for heat treatment, and I need some answers before I order all of my stuff.

Thanks,
-Mike

Ron S

My Feedback: (2)

The last time I made molds, I used the black polyester based resin from Fiberlay , although I also usually use Fiberglast materials. Seemed to work fine for me. [8D]

MHester

My Feedback: (1)

I'm making the molds and parts with MGS epoxy, so I'm looking for the best way to do this.

Thanks though, polyester just won't work for me.

-Mike

Chris Moon

My Feedback: (8)

Mike: Just add their (Fiberglast) black pigment to the surface coat. Does not take that much to get a good solid black color.

tschmidt

My Feedback: (1)

Mike, Chris hit the nail, use the black pigment from fibreglast(its a liquid form). I've been using the green on my molds. I haven't been able to tell any difference in surface coat consistency while using it.

Todd

davidfee

TC-1611 from BJB Enterprises looks pretty good. I haven't used it yet, but it came recommended by a friend.
http://www.bjbenterprises.com/epoxy.html#surface_high

I have used 908-SC from Jeffco quite a bit and I like it.
http://128.121.50.220:8090/Jeffco/Re...tml?key=908-SC

-David

MHester

My Feedback: (1)

Thanks guys. I try and over-analyze everything, it's a curse. I'm going with the pigment and feel dumb for not figuring that one out already! Duh me.

-Mike

Ed Smith

When mixing up the epoxy to make the mold add some West systems #423 Graphite powder and West Systems #406 Colloidal Silica (Cabo-Sil). The quantities are not that important. Say equal amounts of each until you get the resin consistency you want. The result will be a very hard shiny surface in the mold.

Ed S

SCALECRAFT

My Feedback: (13)

Remember to use a good quality respirator when using "cabosil".

People get lung cancer from just breathing"clean" air now days.

Steve

goony

wether using epoxy or polyester just remember that pigment doesnt get hard!!!
so you add say 10% pigment to it then you can only expect the surface to be 90% as hard as it could be!!!

goony

Ed Smith

I always used to. Then I was told by somebody who knows about these things that Cabo-sil is used as a food thickener for numerous processed foods. Whether or not it is true I cannot say. I suppose there is a difference between breathing it and eating it.

Ed S

Chris Moon

My Feedback: (8)

Wow, thanks Ed. I didn't realize that either. I went looking and found this:
"Cabosil is a synthetic, amorphous, untreated fumed silicon dioxide. Because of its inert nature, it has been used in food such as kethcup as well as in shampoo and some cosmetics. When mixed into liquid resin, Cabosil functions as a resin thickener (flow control agent) and sometimes as an anti-settling, anti-caking agent. Its applications are many, including thickening paint, dyes in the screen printing industry, epoxy, polyester, urethane, water, hand soap and shampoo. It is a versatile thickening agent that has even been used to "thicken" fresh water and sea water. " -----not sure what the need for thick water is though.

ptxman

My Feedback: (2)

Why dont you use MGS tooling gel? Its already black, its epoxy, its MGS chemistry, competitively priced to other question mark systems, comes in different hardness/temp flavours...

Polyester + epoxy is, uhm... 'non-optimal'.