Duratec Question

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#1

I have just about finished a plug that will be coated with Duratec Polyester Surfacing Primer, sanded, cut and polished per the application guide. The male plug will be used to create a female mold surfaced with polyester tooling gelcoat and backed with PE/mat/glass. Frekote 770-NC will be used as the release agent between the plug and mold after the plug is treated with Frekote FMS.

I have read that once the mold is finished it should be allowed to sit for at least a week to finish curing before making a part, even when using a semipermanent release. What I cannot find anywhere in the Duratec documentation is how long should I wait before using the polished and sealed plug to make the mold.

What works for you?

SS//

#2

Just take it slow in general and dont rush it.

Most sticking problems come from either using the wrong materials or an uncured material either from an error in mixing/catalyst or not waiting long enough things to cure properly.

Fully cured materials is the key to safe releasing.

For my plugs I let the paint cure for some days.
Then cut, polish, clean, and mold sealers can all happen within the same day but leave the sealer to cure overnight.

Next day frekote only and leave again overnight.

Next for I wax, 5 coats and leave again overnight.

Then go and gel, infuse or whatever.

#3

I pretty much agree with Fasta, however with the Duratec surface primer specifically (and I wouldn’t apply this to regular 2k polyurethane coatings), you can mould off it pretty soon. The process as per the Duratec guidelines, is to DRY sand with 400 grit paper as soon as the coating is hard enough to not clog the paper. This breaks the skin of the coating and allows solvents beneath the surface to be released. You then need to allow it to sit for 8 hours in a dry place before starting to wet sand through the stages up to 1200 grit and finally compound.

You can mould off the surface any time after the 8 hour period.

#4

Thanks.

I had read the Application Guide (page 3 for the primer) (http://www.duratec1.com/Application_Guides/ag13.pdf and was aware of the sanding to break the surface and the wait time, but the guide does not say how soon you can use the polished surface.

The eight or more hours seems reasonable and depending upon the weather, it may be several days before I actually make the mold - I spray the gelcoat outdoors and it has been raining but should clear up soon. Like Fasta, I was used to waiting a week or more before using polyester surfaces, but the other steps for Duratec seemed much quicker so I thought I would ask.

SS//