Prep for epoxy primer

[wiggy]

I'm preparing my keel for epoxy primer over existing fairing that looks like gel coat. Does it really matter if there are small amounts of primer left in very small hollows?

 

[William_H]

I assume your boat has a GRP keel filled with lead or iron. Im which case the keel should be no different to the hull. Epoxy does not tend to dissolve old one pack pant like a polyurethaneor similar. So epoxy should be on on the old primer however it will be relying on the adhesion of the primer to the GRP. Probably OK. I always see work on the hull and keel as a short term job becuase it is always out next winter needing treatment again. So you fix problems then.
If it is a steel keel then grind off all rust etc back to bright metal. however again if primer is oK over good steel then it should be OK. Again you will find out next winter. good luck olewill

 

[wiggy]

keel in cast iron with what looks like gelcoat fairing, I plan to epoxy prime then coppercoat.

 

[oldsaltoz]

I'm preparing my keel for epoxy primer over existing fairing that looks like gel coat. Does it really matter if there are small amounts of primer left in very small hollows?

Hi Wiggy,

I'm a bit confused by your question, You have a cast iron keel that will at some stage be coated with Copper-coat.
In my experience epoxy will stick to just about anything provided it dose no react with it, an epoxy primer is only applied if you suspect a reaction with the surface to be coated. A small spot test on suspect coatings will give an early warning.

Also note that applying an epoxy coat over cast iron will seal in any moisture, so it's very important that the keel is dry before coating.

To form rust only 3 elements are needed, remove any single one of then and no rusting will take place. They are, Oxygen, moisture and steel.

Because cast iron is porous, it's all but impossible to eliminate oxygen trapped in voids, but drying eliminates the moisture component.

By the way, you would need around 5 coats of epoxy for a standard coating, rolled on and tipped off with a brush or pad, wet on tacky to avoid sanding between coats. But, because you plan to add Copper coat you can reduce this because it's an epoxy based product.

Good luck and fair winds.