: I was wondering, First, is it possible to
: glass the outside with epoxy utilizing it's strength and asthetic
: properties while using ployester resin on the inside? This would prove to
: be a considerable cost saving.

You would be doing things backwards. for the same money, reverse your concept. Here is why: The strength and flexibility of epoxy could best be utilized on the interior. If you use polyester, then using it on the exterior would give you 1) a harder finish that would be 2) UV resistant and 3) not need regular varnishing. The epoxy coated interior would need just 2 coats as it is not necessary to fill the weave on the interior, so you'ld (theoretically) save some more here.

The theory breaks down when you consider that the price breaks and packaging on these resins have to be allowed for. It can be cheaper to buy a gallon of epoxy than to buy 2 quarts of epoxy and two quarts of polyester.

There is one other problem which has not been addressed. What type of wood are you using? Years ago, when polyester was the only resin available, white cedar was used for strippers, as opposed to the more readily available red cedar, because the polyester resin stuck better to the white cedar. Epoxy sticks well to either wood, so you could save a few dollars on the wood which helped offset the higher price of the epoxy resin. If you have red cedar you will need to seal it with a coat of lacquer before you apply the polyester resin. It serves as a primer and seals the wood so the natural oils in the cedar (which contribute to its water resistane and rot resistance) do not interfere with the bond. Add on the price of the lacquer and it eats away at the savings for the polyester.

: My concern is can galssed epoxy be joined
: to a glassed Ployester resin surface?

Use epoxy as a "universal" glue for any type of fiberglass. Just rough up the areas to be joined with some sandpaper.

Are they Chemically compatable? are
: the strength properties of Polyester resin compatable with epoxy?

No and no.

But it doesn't matter, either. You are not going to be nuts enough to try and mix an epoxy hardener to a polyester resin, or an epoxy resin to a polyester catalyst. At least not twice. It will fail to cure on your first attempt -- and that should teach you all you'll need to know about the compatibility and chemistry of these resins.

Polyester is strong enough when used properly, as is evidenced by the great number of all fiberglass boats, and the remaining strip and plywood boats that were sheathed with glass cloth and polyester. resin.

When the polyester resin has hardened it is just another plastic that you can glue to with your epoxy resin. the strength of the bond is measured in pounds (or thousands of pounds) per square inch. A larger bonding area gives more strength. Sand it first for better adhesion.

You'll want to invest in twice as many tools (rollers, squeegees, etc.) or in cleaning solvents, so you don't end up mixing bits of one type of resin with the other. The solvents are messy and dangerous. For that matter, the solvents in polyester resin are a lot more hazardous than epoxy resin.

For a safer working environment, stick with epoxy. If you are in an industrial situation where you use large volumes of material and can invest in proper safety equipment, polyester is an economical choice.

hope this helps

PGJ