Hello,

I am re-coat a canoe. I've done this before and all went well. But, this time I think either the surfacing agent was bad or I misapplied it.

It’s been a week since I applied the gelcoat. I applied 3-4 coats with a roller. Each had the correct amount of catalyst in it and was well mixed. The final coat had the surfacing agent in it, but I fear here is where I messed up. In prior gelcoat jobs the surfacing agent was clear, but it cooled it would turn “cloudy” — I assume the wax coming out of solution. This stuff had huge bits of wax floating around even at 75+ degrees.

The surface is "hard" in the sense that it isn't tacky, but I still get tiny amounts under my fingernail if I pick at it. It looks fine until some water gets on it and then it “spots” where the water touches it. After the water is gone the original color returns. I’ve attache a photo.

What are my options at this point? Would covering it with wax work? If I can find it, would PVA work? Or, do I need to sand? If I have to sand, how much? (I ****really*** hope I don’t have to remove all the new layers.)

Thanks so much for any advice.

Sincerely,

Samantha

Are you doing this in direct sunlight? This may be your issue. 75F isn't too bad, but what can happen with the wax when it's too warm (or catalyzed too high for how warm it is) is the gelcoat cures faster than the wax can rise to the surface. Happens ALL the time here in Australia with pool builders and boat builders, they dont like to tarp their job in summer but then they get these issues.

I'd wager this is what it is. If you can keep the boat out of the sunlight while the gelcoat cures then it likely wont happen again. Or if you cant, try dropping the catalyst a little bit (but not too much!)

No, I applied the gelcoat in the shade.

Thanks.

Ok.

Little bit difficult to say then. How much wax solution did you add?

Hi Samantha,

Could you be specific about what products you've used here. At first glance I have a few concerns about the suitability of what you've used and your process but I'm just guessing at what you've used.
Please could you confirm the following:

1. What 'gelcoat' are you using?
2. What was your 'correct amount of catalyst'? - I.e. what was your actual ratio - can you provide the numbers (cl's of catalyst and cl's of resin so I can check your numbers).
3. What 'surfacing agent' are you referring to? I'm assuming wax solution, is it ours? Did you shake it first?

Let me know and (assuming this relates to one or more of our products) I should be able to get to the bottom of what's happening for you.

All the best, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Hi,

Thanks for the replies.

I don't know the brand name of the gelcoat or the surfacing agent. We only have one store in town that sells the stuff and I bought from them. They'll open on Monday and I could ask them then.

I catalyzed 1 pint at a time with 8 cc of MEK and mixed it very well.

The surfacing agent, again don't remember the name, contained wax in suspension, but not completely dissolved at 75 degrees. In times past I remember the surfacing agent as being clear at 75 degrees, but would turn into a solid when it was cold, say, less than 50 degrees, but would become a liquid again when it got near room temp. 

I think my problem is that I used a baster-like gizmo to draw the surfacing agent out of the bottle and measure it. This worked in the past, but then that was with the agent described above that was clear. This time I think all I was getting was the solvent and very little wax.

Today, as the rain stopped and things warmed, the spots shown in the photo have totally gone. But, I know the gelcoat hasn't hardened. I took a bit of acetone and tested and immediately the surface got super tacky.

So, my questions are...

1. It has been a week since I applied the gelcoat. Is it too late to cover the surface in wax/PVA?

2. Assuming it is too late, what do I do now? Sand off the gel coat and start again?

3. I applied 3 coats originally, each catalyzed as described above, have the first two coats fully cured and it is only the top coat that is un-cured? In other words, if I sand off the final coat, can I apply a new final coat over the previous two?

Thanks again for your help. The only good thing about this story is my canoeing season is pretty much over and I won't need this boat until next year. But, I feel like a such a dolt....

-Samantha

It might be worth checking with the supplier to make sure you aren't doing anything obviously wrong. 

Your MEKP catalyst ratio sounds a little high to me for a very warm environment, but again that might be fine if you are using a certain MEKP for your gelcoat.

Speak to your resin supplier before you consider sanding off the gel.  You never know if you've missed something or you just need a bit more time (albeit unlikely).

Remember if your wax additive hasn't worked properly as you suspected, large parts of the gelcoat surface open to air, will be cure inhibited and tacky so adding acetone is likely to make it more tacky/messy and doesn't really tell you anything about the gelcoat below.

You might find the gelcoat has fully cured away from the surface, in which case you can sand through the tacky surface layer down to hard resin which can then be smoothed out and polished back up.

However, this is all best guess at the moment - hopefully a chat with your supplier might clear some of this up or at least give you a clear path forwards.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant