Surface coat
 

Great bunch of threads here.

Can I use a surface coat instead of a poly tooling gel to make my mold?

RE: Surface coat
 

Yes, I use a epoxy surface coat from fibreglast.com. It is white in color but I use their pigment to tint it green. It is wonderful stuff and takes all the stress out of making a mold. It will give you a hard ceramic type surface in your mold. This of coarse needs to be backed up with layers of reinforcement.

Todd

RE: Surface coat
 

I was thinking about using the surface coat that freeman sells. They are a 1/4 mile from my plastic sheet supplier. Just easy for me. I really like the idea of not having to spray. No place to do that in the winter at home. Unless I evac the whole house.

RE: Surface coat
 

Is Polyester Tooling Gel compatible with Epoxy? Like can you put on the ploy tooling gel and then lay up with epoxy or would the entire mold have to be polyester?

RE: Surface coat
 

No it'll all have to be one or the other. If you use a polyester gelcoat, you have to use polyester resin for your CSM or cloth in your mold lay up. Not a problem to then use epoxy or polyester for your final part item. Or do one of each. But you can't mix materials in the same application. Making the the mold out of polyester and the part out of epoxy, I've found to be the most economical way of making things. Quicker too. The polyester "goes off" pretty quick so when you're building up a mold on a plug, you can just keep on putting layer after layer, no need to stop and wait hours for the resin to "go off".

RE: Surface coat
 

Be warned. This is a risky process. Piling the layers on as described can lead to a very fast heat build up which can be dangerous if it gets out of control. Curing generates heat, heat speeds up the cure which creates more heat........ It can get away from you. This type of cure can also lead to the mold shrinking or twisting after the plug is removed.

Ed S

RE: Surface coat
 

Good point Ed and maybe I gave a bad impression of how many layers of CSM I really do at one go. Working in temperatures around 12C on a 5 ft long plug, it takes long enough to do one layer of CSM the full length of the plug, that by the time I'm finished one layer, had a cigarette and a coffee, it's time to start the next layer.

But Ed's right. Too much too soon can certainly generate excess heat and you need to be careful. But there's no getting away from it, polyester is much quicker to work with than epoxy. Using a standard hardener in epoxy, I find it typically takes 4 or 5 hours for each layer to go off, making the whole molding process much more time consuming.