can I pre-coat my frames with Sys. Three expoxy primer?

I have finished building the frames for my boat and I am in the process of encapsulating with epoxy. I want to apply System Three epoxy primer after I finish the encapsulating and it would be a time saver and much easier to do the frames in the primer while they are flat on the bench. My question is can I apply additional epoxy and cloth in the seam fillet areas after the boat is assembled. Will the primer coat cause bonding issues with the epoxy when filleting the seam? Any advice would be appreciated! Thanks!

 

The primer coat will be a much weaker bond joint. IMHO

But you should just do a test and see for your self.

Very few people seem to want an opinion if it counters what they want to do.
Just make a simple T joint with the skin and simulated frame long enough to pull on. 2 flat pieces of wood is good enough, curvature is not required for the skin. Make one with primer then epoxy and cloth, and one without the primer.

 

No.

You can if you want to severely compromise the whole boat's structural integrity. Epoxy primers are the first stage in painting - they are great products but you never paint something before you bond it. Very bad practice.

Instead build the hull with nice clear epoxy surfaces and nice clean glue joints. Then sand and spray epoxy primer inside the whole interior. To get into all the little spots make a little hose that allows you to hold the paint pot upright and twist the spray gun around to point it at all the spots inside. Spraying is fabulous for finicky interiors. Rolling is good for large flat expanses.

You then need to sand the interior before painting unless you are a very good spray painter. A light sand to get the surface smooth is usually all that is required.

Don't epoxy prime till the structure is totally finished. The day you epoxy prime is a great day. It is the first time your hull goes from being a collection of parts into one homogenous whole.

 

I see the point and I appreciate the advice. I suspected it would be a problem but I wanted to hear from those who have more experience. Thanks folks!

 

Catsketcher has it and typically you'd prefer to have straight epoxy to epoxy bonds, the best being chemical bonds, though mechnical are perfectly acceptable and often the only choice.

SystemThree and West System are industry leaders in the goo department, but they are also industry leaders in pricing too. There are several discount epoxy formulators you should consider, selling products with the same physical attributes as the big boys at 1/2 to 1/3 the price.

Try Epoxyproducts.com (forum member owened and good goo too), RAKA.com, Bateau.com and bandbyachtdesigns.com for the better prices for the same stuff the major players sell. Lastly, check out my "Tips and Tricks" page for a quick look at techniques and methods.