Can fresh epoxy retard cure of interlux bilgecote?

[mishnish]

As per subject...

One of my lockers under the vee berth was very rough and had resin starved areas, so I decided to apply a light surface tissue with epoxy to get back to a nice uniform surface before painting out the area. The laminating went well. After a day of cure at approx. 12 degrees centigrade I solvent washed and sanded the surface in preparation for paint, then the next day I applied interlux bilgecote (international danboline here in the uk) by roller. now after 2 weeks I still have a slightly tacky painted surface, where as other surfaces with out the epoxy pre treatment have cured to a nice solid hard paint surface.

Can fresh epoxy inhibit cure of bilgecote? What can I do about this? Will leaving it for as long as I can then another coat of bilgecote get me back to a nice hard final paint layer?

looking forward to hearing any experience on this!

Best regards

Chris
http://www.contradanza.co.uk

[Rachel]

Can fresh epoxy inhibit cure of bilgecote?

My guess would be yes. I used Bilgekote over some "new" epoxy, and I went with their method of water washing/drying, then solvent washing, then using Epoxy Prime Kote as a tie coat (I believe it is now called Epoxy Barrier Kote... yellow cans at any rate), and then finally the Bilgekote. I actually wondered to myself why I was "downgrading" to a one-part paint after all that!

I don't remember all the details now, but at the time I had got the idea (from reading their literature) that there might be adhesion problems if directly going over newer epoxy with Bilgekote. Relatedly, if there's one thing that annoys me about Interlux, it's that at times I'm pretty sure I've found different guidelines on different data sheets, pertaining to the same products. It seemed some instruction versions were more liberal, and then tech support might give a third answer. I found that exasperating when I was trying to figure out how to do the best job.

I just looked up the US datasheet for Bilgekote to make sure I wasn't giving you wrong information, since it's been a couple of years. It does specify the tie coat, but I also seem to remember finding information somewhere else (at that time) that showed the tie coat was optional; here they make it sound like "the" method. Just out of comparative curiosity, what did your (non-US) instructions recommend? I always wonder if they are different (as I think I have seen slightly different ones for the UK).

http://www.yachtpaint.com/MPYACMDatashe ... 100520.pdf

The pertinent passage from the Bilgekote data sheet, about putting it over epoxy. The 404/414 is what used to be called Epoxy Prime Kote, I believe:
CLEAR EPOXY Begin by scrubbing well using soap and water and a stiff brush. Rinse with fresh water and allow to dry. Degrease by wiping with a rag soaked in Fiberglass Solvent Wash 202. Sand with 80 grade (grit) paper. Remove sanding residue. Apply one coat of Epoxy Barrier-Kote 404/414.

As far as what to do now... I'm not sure. Ugh! If it were the epoxy not curing, I would probably try putting a heat lamp on it. But in this case it seems like it's a matter of the (alkyd) Bilgekote having the problem vs. any problem with the epoxy. I don't understand the chemistry of the interference enough to really understand it though. I hope someone else here does. I would probably be doing the same thing you are doing to start with - gathering information - and then if necessary proceeding in this order:

1) Check here on Plastic Classic
2) Call Interlux tech support
3) Ask a friend who does a lot of painting
4) If no better answer, curse and strip off Bilgekote so I could start again

Nice to see you around here again,
Rachel

[mishnish]

That is an interesting thought....

Conditions for the paint were cool to cold, with little ventilation. I do tend to put my paint on thick... Also, owing to the locker being deep and contained, evaporating solvents may have sat within the confines of the locker. The epoxy definitely kicked hard and good, and was well prepared before painting.

seems like this could be a good starting point...

My paint instructions don't mention any tie coat, merely that it can be applied without primer over bare fibreglass.

I like the thought of abrading and seeing what happens. I have to overcoat in here anyway so I will give this a try... We are coming into the winter here in Scotland and I have to keep heat on in the boat while working these days!

Thankyou all for the compliments! Contradanza is a fun project to work on these days as the hard prep work is over, the materials are in stock to get the interior fabricated, and visual progress is quick and easy in this stage!

[Quetzalsailor]

I believe that West System epoxy retarded the cure of Interlux's Brightside Polyurethane. When I grumped to Interlux, they said that I had not properly cleaned the epoxy, but, since I had wet sanded it and wiped it down afterwards with lacquer solvent, I doubt much remained of the amine. The Brightside eventually cured. Some few areas in a later application showed lack of adhesion, but with adequate cure; these might well have not been adequately cleaned.

[Tallystick]

You can try blasting the tacky area with an electric space heater to remove any solvent or water in the coating. Just be careful with the temps not to get too hot. 100-150F should do it.

[Rachel]

My paint instructions don't mention any tie coat, merely that it can be applied without primer over bare fibreglass.

I guess my frustration with inconsistency is still valid then. Why do they do that? The part I quoted in italics above was straight from the Bilgekote product data sheet, for going over clear epoxy.

Even if the epoxy didn't cause your problem* .... how is one supposed to make a clear decision when instructions from the manufacturer contradict each other? I really don't like to have to call tech support for something that should be that straightforward.

*And it may not have; trapped solvents sounds very plausible to me -- thick varnish application will do that readily, and sometimes it just won't "dry" until you break into the pockets of "thick."

[mishnish]

more points of interest:

1. I am using West Epoxy!
2. It does seem to be very slowly curing...
3. I will try blasting it with the space heater for a couple of hours today
4. had it told me to use a tie coat, I would have used a tie coat! Bloody annoying!
5. In my mind the only thing that changed from when I painted my other deep unventilated locker was the epoxy surface coat. The other locker has paint cured to a nice hard layer... madness! lol!

[JohnD]

I'm pretty sure my can says it is good for fiberglass, but to call Interlux before applying over epoxy or resin. Hopefully I can get out to the boat tomorrow and check to be sure.

[Rachel]

I have had the idea in mind (one of those things you feel like you "know" but perhaps not authoritatively enough to pronounce as fact) that there could be issues in painting over relatively fresh epoxy resin. I decided to check on WEST System's website, since they often have good information/tests/etc. I found a troubleshooting section on "Paint or varnish will not set up over epoxy"

The page is here:
http://www.westsystem.com/ss/problem-so ... nt-varnish

Since the paint dried on the non-epoxy coated lockers, it does seem reasonable to think that it might be a problem with the epoxy. Since WEST say to wait "several days at cooler temperatures with slow hardener," maybe one day at :converts:... 53ºF was not enough time? Maybe even if the epoxy seems "hard," there can still be chemical curing taking place that causes a paint problem? I know that for epoxy sanding they warn to be sure to still cover your skin to avoid sensitivities because even though it is not "green" enough to officially be in the green stage after a week or so it is still technically not cured.

I still am not against the "thick coat of paint can skin over and retard drying" philosophy, but then your other, not-epoxied, painted lockers cured fine, and it seems like if anything, you would have a thinner layer of paint on a nice smooth, sanded layer of epoxy on this locker vs. the other "old fiberglass" lockers.

Rachel

[Quetzalsailor]

Gee, thanks, Rachel, for reminding us guys: 'When all else fails, read the instructions'!

[Rachel]

Well see I have the "advantage" that no-one in my family did projects, and I also never soaked them up through osmosis, or whatever it is that makes some people grow up just "knowing" how to do stuff. So I have to read them!

(I also do kind of like to read them; maps, too :)

(That said, I am envious of those people who grew up around shops and have all that wonderful, soaked-in knowledge.)

[bristol27]

I wanted to add some additional information to this thread for future reference. I called Interlux with a few questions about this very same situation. Here's what I asked, plus what they answered:

Q: What do I need to know about applying Bilgekote over epoxy?
A: Wash, water soap & stiff brush, then go ahead with 2-part primer (epoxy prime coat Y404), then apply bilgekote over the top of that.

Q: Do I need to use thinner for Bilgekote? What is the ratio?
A: Not necessarily, out of the can you should be apply it. If it's hot in the area or a little thick in the can, you have the option to. Kind of a feel thing at that point. I will, however, need to use 2333N Thinner for the primer.

Q: Do most people paint the interior of their lockers with Bilgekote or another product?
A: Not unheard of, no problem doing it just depends what I'm doing. I can definitely paint it over wood.

[mishnish]

Wow! Nice one Rachel, I had a feeling I had seen this somewhere before, and it was what I was worrying about. I think I just didn't leave enough time for the epoxy to fully cure in the cold conditions as I was trying to press on and get the berth tops on.

So.... My remedial work happened yesterday.

I tried sanding the surface off as suggested, and I clogged up 2x 40 grit discs. The paint was tacky all the way through, but it was lifting fairly cleanly. So I got the respirator on and glugged a cupful of acetone into the locker and washed it around with a brush. The paint just fell off, clean back to bare glass work. I took up the residue with paper towel and did a final acetone wash, then sanded it all out again until nothing was gumming up on the disc. Another Acetone wash and I reckon I am back to first base on this one! I will wait another week at least before over coating, and I am almost tempted to curtail epoxy work over the winter just in case I am not curing the epoxy properly in the temperatures I am working at... I do heat the boat before work, but the hull is cold and I am a little worried that it will rob any curing epoxy of the heat it needs to cure... or am I being a big jessy here!? lol!

I was particularly surprised in my case that there was next to no cure at all in my paint... I definitely reckon it was the Epoxy and its state of cure at the time of over painting... Take heed!

[Tallystick]

If the hull is cold you can expect that to dramatically slow the cure of the epoxy, since the reaction is temperature dependent. If you are interested in the theory relating to epoxy cure, this paper has some good info: http://www.google.com/url?sa=t&rct=j&q= ... 6ZXlCZ7-1w

There are epoxies that cure at low (above freezing) temperatures such as this one: http://generalpolymers.com/3526.pdf

Not sure if there is a similar product for the marine market. I'd suspect the above product would likely do the job, but I'd advise contacting them for more information.

[mishnish]

Nice one Northstar, I reckon that closes out this issue...

To conclude (like we don't all know this already, but occasionally need reminded!):

1. Let your epoxy cure for a good bit if in any doubt over temperature, say a week or so
2. Water wash first(not solvent! but you could solvent wash subsequent to water wash) before additional bonding or painting work
3. Ensure adequate ventilation and temperature during subsequent bonding/coating!

Had I done the above, the likelihood is I would not have had to remove the coating and try again. In my case I was rushing and only sanded and solvent washed after allowing an inadequate cure time considering the temperature. As the other locker without the epoxy lining did okay in the temperatures and ventilation, I reckon point 3 is less critical, but still good practice!

So I reckon I am ready to go again and see if I can get some paint into this locker before I glue the berth top down... Its so much nicer not having to work through the berth top and trying to avoid getting paint on what will become a bright finished berth!

Good work everyone!
Chris