Question about molds...

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#1

Hi guys,

I’m a boat builder in North Carolina, and deal mostly with old wooden boats and polyester boat repair with epoxy. http://83footernoel.blogspot.com/

I’m looking into goofing off with some polyester mold, out of mat, and am curious about gelcoat.

I’ve used boatyard gelcoat, that is waxed to refinish bathtubs and roll on various projects. Does a waxed gelcoat work to spray in and mold a part or does it need to be un-waxed?

How long do you wait after spraying the gelcoat, to start laying glass?

I have heard that storing a mold, you want to spray a gelcoat in and can come back in a year and either lay a thin part to remove the gel… or lay up an actual part full thickness. Is this accurate, can you really come back that long after?

Thanks,

Zach

#2

I only use tooling get coat for my molds. I am sure you will not want to use a gel coat with wax in it. That is a surface curing agent. If you want to go cheap on your mold. Just use some regular gel coat that is meant for making gel coated parts. Most suppliers will have some odd color they can’t get rid of. So they will discount it.

#3

Cool,

I have on the way 5 gallons of tooling gel, 5 gallons of laminating resin, and 5 gallons of white gelcoat… a gallon of hardener, and some other goodies. I’ve got a few sheets of divinycell to play with and I’m pondering popping a mold off my sliding hatch cover on my sailboat.

Is 5.50 a pound for tooling gel, 2.02 for laminating resin, and 4.040 a pound for white gel?

What are you guys paying per pound of 1 ounce, and 1.5 ounce mat? I’ve got a quote for 1 oz at 1.37 a pound, and 1.5 and 2.0 ounce at 1.20 a pound. (50 inch widths)

One that blew me away, was a quote for peel ply… 7.95 a yard? 300 yard roll! Is that anywhere in this universe?

Thanks much…

Zach

#4

Peel ply comes in various grades and of course prices. You generally get what you pay for. Having said that we used the cheep stuff on flat surfaces and the good stuff on complex shapes to cut costs. Prices up here on the west coast of Canada are generally way more than what you pay down in NC. When shopping for your materials go for quality over cost of material. While you can do a xxxxty job with good materials it is way harder to do a good job with xxxxty materials.

#5

Thats good to know. Nothing like committing to a roll of something that turns out worthless for the use you have in mind!

I’ve got some more pricing pulled in…

Are Airtech Econoply J and Econolease decent products?

At the moment the only experience I have with peelply is a couple yards from a west systems sample pack doing some flat divinycell panels. I’ve done all hand lay up and repair work, where a hot coat of glass microballoons and slow or tropical epoxy hardener gets mopped on and ground off the next day to fill the weave on painted parts.

Is polyester like epoxy, in that a week later the parts are still shrinking? I do the microballoons to prevent print through in the finished part where Awlgrips Awlfair directly into the weave of the fabric continues to shrink and the paint job today looks great but next year shows print through.

Does the silicone release agent on the econolease cause adhesion issues further down the road? (Silicone is a curse word in my realm…)

Thanks,

Zach