I was looking online at Polymer Products store for some white marble filler for epoxy. Is all calcium carbonate made from purified white marble?
I’m just hunting around for the best price is all. Not everyone advertises their calcium carbonate as “marble calcium carbonate”.
So I guess the question is… calcium carbonate retrieved from marble; is a harder mineral than calcium carbonate from the ocean or other rocks? It kinda seems to me if the maker/seller of marble calcium carbonate is saying it’s from marble… either it’s better or it’s just a marketing gimic.
whats your plan with this calcium filler?
calcium carbonate is calcium carbonate, I suppose it could be an amorphous solid form instead of crystalline solid.
It could also have other trace minerals (from mining) in it if it’s not a calcium carbonate precipitate.
Fast: You trying to make your own surface coat or something?
Yeah JRL. I’m getting away from using PER for molds. My thoughts were this will make the epoxy harder and thicker for a good surface coat. Was going to buy some aluminum powder and still can, problem there was i wanted a bright yellow surface coat, and I thought the silver-grey color may not allow for that.
edit: I just ordered a quart size container of the marble stuff…
http://cgi.ebay.com/Calcium-Carbonate-Marble-Powder-EpoxyFiller-325-Mesh-3_W0QQitemZ270167122034QQihZ017QQcategoryZ26197QQtcZphotoQQssPageNameZWDVWQQrdZ1QQcmdZViewItem
shrugs I’d still only use tooling gelcoat, and MAYBE some cabosil.
But I guess if mineral rock filler works.
hell, just CNC some marble? 
When do you apply the first skin coat? Same as if you were using poly to build the mold? Or do you wait for the gel to completely dry to avoid a reaction with the epoxy?
aren’t there epoxy gelcoats out there?
If anything, why not use carbon dust? instead of calcium carbonate?
Yeah, there are epoxy surface coats out there, but they cost a lot. Like $35 for one quart… and the price doesn’t really go down much if i were to buy more… maybe a few dollars per quart less. Just cheaper to make my own and experiment with it.
Another friend of mine uses PER gel coat then backs it up with epoxy resin and fiberglass. I don’t know how well it would work.
I’m telling ya, if i had full access and knowledge of CNC programing I would make some molds from aluminum tooling plate. For now, i’m lucky to sneak in my small projects when the boss isn’t looking. Last place i used to work at ( machine shop ) a couple of the guys used to bring their guns into work and modify them, make parts for them on the company machines. Crazy. they’d make semi autos full auto and stuff.
you want to apply the first coat of epoxy gelcoat to the plug surface(10-12 mils thick), let it tack up the same as you would with poly gel, then apply second coat as a coupler layer, immediatley begin laying up. epoxy does not attack the gelcoat as like poly since there is no styrene
Oh, my bad I was confused.
When he said “gelcoat” I thought he was using poly gel and then backing it with epoxy/glass. Which is why I was curious how he was laying it up and not getting some type of reaction between the poly/epoxy.
actually there are system that you can use that use a poly gel with epoxy layup. benifits are you can spray the gelcoat. you would spray two layers of gelcoat as you would if you are doing a poly layup. wait for the last layer to fully tack as usual, then proceed with the epoxy layup. actually works well and the system I have used was hightemp up to 300
Thats good to know. I was actually considering using a poly gelcoat, backed with a vynil/glass skin coat. Then sand and finish the mold using epoxy/glass.
Only reason I want to do it this way is that I find it easier to get a perfect skin coat using vynil/mat vs. epoxy/glass.
no, it’s all epoxy. the tooling coat, and then the tooling resin (what you use with the glass/carbon/whatever)
I think airtech sold it, it was 100A/B and 50A/B…i think the high temp was the 2000 and 5000 series.
I got this email info from Polymer Products Inc.
Question was: What is the difference between marble calcium carbonate and other calcium carbonate.
"Hello,
There are many factors which makes one type of CaC03 better than another. The shape and size of the particle, the treatment and other post processing will determine its efficiency as an epoxy filler. The Calcium Carbonate we sell is treated especially as filler for liquid polymers and provides the highest filler loading without making the mixture to high in viscosity. Its particle shape also allows low air entrapment thus reducing porosity which lowers mechanical properties.
In general Calcium Carbonate is generic, what makes it different for one to another is it designed processing for its end use. Thanks for the inquiry.
Gerald "