Thread: Epoxy on Timber problems....help

Welcome to the forum Eagle.

I'm not sure what UV inhibitors might be in "spa varnish", but if you meant spar varnish, you shouldn't have had a reaction. This said, some species of wood darken when first exposed to sunlight, though this is usually just a shade or two, not black. A black color often indicates water has gotten into the wood. Can you post some pictures?

Hey Par,

Thanks for replying, photo.JPGphoto1.JPGphoto2.JPGIts actually the styro-foam outriggers not the timber hull, thank god. photo3.JPGThe indication that i have from the supplier is i should use a two part varnish as the epoxy is two part. i am a little confused i must say. Sounds a little fishy however it would seem i wouldnt know. I was also told i cannot put a two part varnish over a one part varnish. Therefore i believe i have to sand it all of and start again. Sorry I haven't really got the hang of this page yet so there's photo's al through the text.

Is the supplier a specialist plastic/marine supplier, or just a paint shop?

I've overcoated epoxy with single pack paints (car acrylic lacquers) and had no problem. I've found that trade paint suppliers who mainly stock house paints really have no idea when it comes to anything other than house paints even though they stock other types of paint. (if you want to be finicky, then standard polyester bog is a 2k finish as well, and every man and their dog spray over that!)

What he is describing (don't put a 1k paint under a 2k) refers to automotive refinishing (the 2k is a little less flexible than 1k, and the solvents in the 2k can do nasty things to 1k paints, both of which lead to poor adhesion of the 2k).

See here for more (straight from the people who popularised epoxy for boats) Finish Coatings

I agree with Splinter, in that your paint supplier, probably doesn't have a clue about the products they're selling, other than the advertising fluff they've read on the side of the can.

Some of the chemistry can get pretty complex, but generally these sorts of problems are prep related, not product. It might be possible that you've reached an incompatibility situation, which occurs, but not often. Typically with incompatibility issues, the bond isn't good and you see clear signs it's not going to stick well, orange peel, splits, checks, cracks, fish eyes, etc. Discoloration is a rare thing and usually a contaminate type of deal.

To help, you'll have to provide the precise products you've used and what they are used over. For example, what is the foam covered with, primer type, what was the sand paper used (believe it or not, some types of sand paper can screw up a paint job), the top coat brand, etc., etc., etc. With this in hand I can check known comparability issues.

As a rule, you can paint anything over epoxy, though some alkyds do have issues with some epoxies, it's not too common. You don't even need primer in most cases, though primer has a few other uses, that are beneficial in a good paint job.

Since it's already screwed up, try taking a good look at what's going on, maybe by sanding a small patch and checking adhesion, maybe moisture, etc. I mean obviously you're in up to your hips now, so a repaint is likely in order anyway and what's the harm at this point. Also some larger images of the darkened areas on the outrigger booms might be helpful. If I venture a guess, I think is a moisture problem. In addition to the list of materials also note what the environmental conditions (temperature, humidity, etc.) where when she was painted.

Hey guys,

Heres were were at,

Mistake 1.

I bought my Goldspar marine varnish from a general marine outlet.

Mistake 2.

I wanted to get the coats on quickly, so waited till its was 35-40 degrees for a week straight, then applied a coat every day for a week.

Mistake 3.

Put it out in the sun, last coat slightly tacky.

i have since been in contact with a very experience marine supplier and he has suggested the following as an analasis, and solution.

As epoxy alone in direct sunlight takes 3 months or so to go cloudy he has suggested the issue is in the varnish itself. The lesser of two evils by far. Lets hope hes correct.

He has suggested that there is moisture in the varnish. It was also very humid despite the fact it was so hot so that stacks up. He has suggested that the outriggers have discoloured due to the varnish blushing....not sure what that means but he seems to know what hes taking about.

Solution, as i have been at this for two years now this is what is going to happen. i will take it to a proffesional marine varnish applier, get three quotes. have them remove the varnish and apply 5 coats of two pack, sand with 320 grit wet and dry, then 3 more coats and that should be it. i have entirely blown my budget but as i am nuts deep what else am i going to do. i can't allow Japanese ceder to be forever obscured by my fubblings of finishes.

I have attched some close ups to help show th eissue a little closer. Almost enough to make me cry, i think i may have at some stage.

Thank you for your assistance and I'll let you know how it turns out.

Kind regards photoc.JPGphotob.JPGphotoa.JPG

Eagle 1.

I think you can handle the revarnish job. I also agree with your local varnish expert, in that (as I suspected) it was likely moisture.

The simple path is to wet sand the varnish back down to the epoxy and see if the color (dark) is still there. It's very probable the dark color will start to go away as you sand through it. I recommend wet sanding simply to save you a lot or prep time later. You could dry sand too.

This means the whole surface (varnish) should be suspect and needs to be removed. You can do this in stages, by concentrating on the dark areas and get them un-darkened, then a good scuff on the other areas that seem okay. Start with 220 and as the last sand (wet) step up to 280. You don't need finer than this, unless you look at your boat with binoculars from 10' away.

If you can't get the dark to come out, it's in the epoxy and you'll have some inventive cursing to do.

Varnish blushing isn't something seen much any more, but with lacquer and shellac base formulations it was once common. Most are now polymer or acrylic base, so this isn't that common. I'm not sure of the brand you used, but it surely does explain a lot of things.

I'm betting that both your local varnisher and I have guessed correctly and you've got some moisture in the varnish, during the first go around. Consider this a trial run for doing it right this time. Clear coat finishes are the hardest to do (well), but with good prep and reasonable conditions, you can have a good looking finish, you can be proud of (honest).

Lastly, if it's hot and humid, consider building a quick paint booth. Some 1x2's, toss some plastic sheeting over it and stick a wall/window mounted A/C unit at one end (this is what I used to do). Yeah it'll eat a bunch of electricity during the process, but it'll be enough to give you several hours of climate controlled conditions, inside the "booth" for the varnish to "lay down" pretty.

Thank you Par, i'll report in 5 days and let you know where It's at. Eagle 1

Originally Posted by Jeremy Eagleton

Mistake 1.

I bought my Goldspar marine varnish from a general marine outlet.

Jeremy,

This is not a mistake. Goldspar is an excellent quality varnish.

I have been using it for 3 decades over bare timber and over epoxy. Never had a problem with it.

Good luck anyway.

Cheers, Cameron.

Here's the deal,

i have sanded back a small portion and it seems that the white disclolouration is in the epoxy not the varnish.

The epoxt went white in a few hours.

The boat guy i spoke to said the epoxy must be to thick and potentially have moisture in it.

He has suggested the following.

1. Remove all 1 pack with paint remover, he also suggested doing so with thiners.
2. Sand the epoxt back almost to the timber where its whits and thin down by sanding all over.
3. Sit boat in the sun and see if dicolouration continues.

if it does not continue i can put 2 pack on.

I am having trouble understanding how epoxy can go white in a few hours, freeling very hard done by. Boat is not far off being a write off.

I have accepted the boat will now take several more months.

If anyone has eperience with this situation please let me know as i don't want to make another serious error.

Eagle 1, down.

I don't understand, you have black marks, but now they're white?

Epoxy will turn white as it's sanded, but will go clear again, if you wet it with a solvent, water, any type of clear coat (varnish, etc.) or more epoxy.

Did the sanding remove the black areas? Of course, the only way to tell is to wet the area, so you can see what it actually looks like (another reason for my wet sanding recommendation). If the epoxy is milky after it's been wetted with mineral spirits or water, there's something odd going on. This would be pretty unusual for epoxy.

Generally, there's a rule about these sort of things - when in doubt, knock it back and do it again. What this means in your case and again much like you local expert suggests, is to sand it back until you're at the wood or very near so, then start the process over again, with more epoxy (if you think it's necessary) and the clear finish.

The only thing I can think of is, the epoxy may have been put over a water based stain while it was still damp.

Hi Par,

Thanks for your reply,

Sorry to clarify , the outriggers are styro- foam with red pimented epoxy and spar varnish . They went black.

The body of the boat is timber, untreated, with epoxy on top. This went white.

I removed some varnish , wet it, and it seemed to still be white in the epoxy. The guy suggested it was on to thick in area's and may have got moisture in it at some stage.

i will remove the spar varnish , with paint stripper, i was told this is ok can you confirm? Sand the whole boat back to reduce the thicker area's of epoxy.

He suggested i then sit it out in the sun before i proceed any further to test it.

We will then apply a small section of two pack, put it in the sun and test it. If all is well apply the rest of the two pack.

i have recovered from my intial disapointment and relize that the application of these materials is a real art form, back to the salt mines. ucky i don't do this for a living.

i very much appreciate your feedback.

Regards Eagle 1.

Epoxy doesn't get milky if applied too thick, just a deeper amber color. At this point understanding what happened isn't as important as moving on. A milky color is usually trapped air bubbles, from mixing or out gassing. Epoxy also will "chalk" up if left unprotected from UV, but this takes some time. Enough moisture in the epoxy to cause discoloration, would also screw with the cure, which seems good (my assumption).

Yep, sand it back. If you do use a chemical stripper, use the type designed for using on fiberglass. Epoxy is tolerant of most chemicals, but strippers can be pretty nasty. Neutralize the areas with lots of water, then a final wet sand to scrub the surface clean. Letting it sit in the sun probably wouldn't hurt, but it's probably not going to help either, as the epoxy has already sealed the lumber. Also leaving the boat in the sun could promote out gassing, so let it cool before putting on finish. Insure the finish is cured (24 hours) before putting back in the sunshine.

Thanks Par,

The guy said to sand the hell out of the whole boat after removing the varnish, should i do this or only the milky areas' ?

Eagle 1.

Obviously the previous prep is to be questioned, so sand everything and make it right this time, other wise you're relying on the previous prep and you know how that worked out. In short, always work from a level playing field and if in doubt, level it again.