There are many variables. Type of resin. Casting or laminating. Age of resin. etc In my somewhat linited use. Mostly fenders and hoods. I like the stuff the boat builders use. Better consistancy. Handles and works better than the gallons that you get at the Mc Parts store..
My father had some from West Marine and you could add some powder to it to change the consistency. Problem was it was it was so damned hard it was tough to sand.
Marine. Find your local boat builder, take along a couple of empty/clean gallon containers for resin and acetone. A smaller 1 for catalyst. You'll buy it far cheaper from their drums, if they are happy to oblige. They'll have matte in stock also.
There are different grades of resin and as mentioned different types. Laminating resin will stay sticky on the surface so successive layers will adhere to it where as a finishing type resin has a wax type additive that creates a film to give a non sticky top surface. What are you doing with it?
Are you using all fiberglass, or will you possibly be using Kevlar or carbon fiber too? Supposedly only epoxy resin sticks well to the fancy fibers. I believe most "fiberglass" car parts are made with Polyester resin. It is cheap but shrinks and is relatively weak, especially When doing repairs since at the bond line It uses a big portion of its strength just trying to hang on and resist its own shrinkage. Some industries say it is unsuitable for repairs, just for original fabrication. Polyester resin has pretty poor moisture blocking capabilities, so supposedly since the 80s even many production boats are using vinyl ester for the gel coat. Vinyl Ester resins are stronger than polyester resins, and like polyester don;t have great bond strength for repairs or attaching finished parts to each other. Epoxy is strong, doesn;t shrink much at all (which helps keep it's bond strength very high), sticks very well to itself, steel or polyester resin, but costs a lot more. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters.
I'm putting this inside a door with pinholes on the bottom, nothing that will ever be seen on the outside. I know it isn't a 100% correct fix, but is sure is perfect for a 1960 build. Bob
If I were you I would get one of the Epoxy based panel adhesives and use that. It will have much better adhesion to the metal, will still be water proof and will be much easier to apply. If you don't have the specialized gun for side by side cartridges companies like Evercoat make a 2K product that works in a caulking gun. http://www.evercoat.com/productDetail.aspx?pID=242
JB Weld is superior to fiberglass when repairing pin holes. Done it both ways. Learned JB Weld is far better, lasts longer, and doesn't delaminate. Make sure you have bare metal and removed any rust. I then sprayed epoxy primer over the repair.
You can use POR-15 for a job like that. Probably stick better to the steel, even is rust is present. Last forever, even in wet environments. Just use the POR like you would the resin.
West system is the best epoxy out there. Just wash it with water before sanding to get rid of the amean blush
Epoxy yes, but look at what temperature the epoxy can endure. Most boat epoxies are too low in HDT - heat deflection temperature, when the epoxy gets soft. Look for epoxy with at least 180 degrees; cars can get hot. JB Weld fits the bill if you don't need a lot. Can be bought in small tins rather than tiny tubes. The bonding adhesives mentioned earlier are also good. All need bare unrusty metal. BTW, none of these are fiberglass resin - different animal.
Most Polyester resins don't stick to steel, Epoxy is what you need, but you will a good clean roughed-up surface. You will also need matting or better still a woven type cloth that is for epoxy. Epoxy contains no styrene so it won't break down the binders that hold the matting for poly systems together. Scotty
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