Gelcoat repair

J

jstates

New member
I am trying to patch a scratch near water line. When I was at the SBS factory dinner earlier this year, one of the staff gave me three cans of
MEK, Gelcoat and Catalyst. He said mix them all together - they have different volumes and the Catalyst has evaporated.

I had been waiting for hot and dry weather to do the repair

Three questions:

What type of catalyst should I use? - Can I obtain that locally - WMarine or Boaters World?

What ratio of mix should I use, with the factory products?



I would prefer to match the color and not use one of the all in one tube preparations.

Thanks

Jim
 
Thanks

Actually I have searched the CBrat site, West Systems and some Kayak repair sites over the last few months about gelcoat repair -

What is confusing is the three cans from the factory labeled as: Gelcoat, MEK and Catalyst [now empty] and the statement below from the CBrat forum that indicates I only need to mix the Gelcoat and MEK - so where does the third empty [I assume evaporated] can labeled catalyst fit in this?

"The actual repair mixes the colored gelcoat provided by the factory ( or other vendors mentioned in other threads) with hardener which is really just MEK (Methyl ethyl ketone) in the proper proportions. Mixing a small batch (in a paper cup) is a bit challenging because one drop of MEK is usually overkill, so ya gotta make the drop small and ONLY ONE!"

I am sure it would be easier to purchase a West Systems product group that comes with mixing instructions.

Jim
 
Jim-

The catalyst or hardener used for polyester resins, like the gelcoat, is methy ethyl keytone peroxide.

The methyl ethyl keytone, or MEK, may just be a solvent for clean up, or more probably, spraying the gel coat.

Bob (Thataway) is more familiar with resin systems, and maybe he will note this thread and respond.

Joe.
 
Joe is absolutely correct: Methyl ethyl ketone peroxide is the catalyst, MEK is a solvent. I have no idea why you were given the three cans or the catalyst in a can. It usually comes in a plastic tube or bottle.

Roger's excellent post gives very good instructions. The amount of catalyst depends on the temperature--but his starting point of 4 drops an oz is a place to start. If it is a cool area, you may well have to increase the amount. Take a small amount of the gel coat paste and experiment with a drop, and two drops of catalyst. As Roger noted, you need to occlude the surface. I like to spray with Poly vinly alcohol (mold release agent) or use a piece of mylar/or Sarran wrap.

Epoxy is stronger, but difficult to match the color and does not have good UV resistance, so use of the polyseter is correct.

You can buy the catalyst at Home Depot, West Marine or hobby shops.
I don't know how big an area--or how much gel coat you will need, that is why I suggest the experiment first--you will learn to work with it--and if it is a can, there will be plenty to play with.
 
Thanks -for clarifying the difference between the solvent and the catalyst. I purchased the MEKP - and did most of the repair - the wet sanding worked out so that the match is close - it really is about timing -
when to quit working the resin, when to pull the plastic off and start the sanding.

Here is a site on patching fiberglass kayaks that has some good photos and step by step instructions.


http://atlantickayaktours.com/Pages/Exp ... nter.shtml

thanks for all the help today.

Jim
 
Back
Top