oil paint over epoxy: drying time?

[davebrown]

i just finished the last bit of epoxy necessary to complete my whisp hull (which, btw, has now taken three months for god's sake). i glassed the bottom in 6 oz and now have finished a second coat to make sure the weave was all coated.

i did this at about 10 this a.m. before going to work, and used medium tap's plastic 143. it is expected to hit about 90 or high 80s by this evening here in sac.

do you guys think that enough time will elapse between now and say 8 p.m. to put down the first coat of oil primer? i am topcoating in oil based enamel with oil primer.

[Ian McColgin]

No. Give it another day, sand, tack with some acetone on the rag, and paint tomorrow.

G'luck

[P.I. Stazzer-Newt]

What Ian said.

Be very very sure that the epoxy has cured before trying to paint - I rushed this once and clearing up the mess took ten times as long.

[Todd Bradshaw]

Even a day is pushing your luck to some extent. A lot of epoxy resins take the better part of a week or more to really finish curing. Until they do, they may not be a particularly stable base to paint over.

[KMacDonald]

I would use an epoxy base primer.

[davebrown]

thanks fellers. i will at least wait until tomorrow.

btw, the taps plastic, as opposed to west or raka, seems particulary reactive to my skin. i am very careful to wear protective gear, but the other day i got two drops on a shirt wihch i then felt on the skin. they were each about the size of a pinhead. it set me on fire! i burned for a half a day,a nd i washed it off vigorously too. i haven't noticed that with raka or west--but again, i am very cautious about that. epoxy reactiveness has been compared with poison oak, and if that is true, then i don't want to ever react to it.

[RodB]

Some epoxys continue to give off free amines, which interfere with the Cobalt dryers in paint. System Three suggests using their "clearcoat" or SB 112 resin if you want to apply oil base paint or gelcoat atop of it. The other solution is to apply a primer/barrier coat such as Parker's 1640 basecoat or Petit has the exact same product... which is a high build primer that sands beautifully and dries PDQ. Of course epoxy primers do a great job too.

Good luck,

RodB

[gert]

What Rob said about a barrier coat.

I painted Carina twice because I could scrape her first paint job off with my thumb nail; and that was 3 weeks later.

I believe the primer/sealer I eventually used was xylene based.

[RodB]

The solvent for the Parker Paint 1640 basecoat is Xylol (Xylene) and its so easy to slop on a couple of coats with a brush... sandable within 2-3 hours in warm weather. I have the number of the same product from Petit, I just need to find it.

System Three standard resin will cause paint drying problems 100% of the time because of the free amines that continue to be released from the epoxy... even after a few weeks. Thus, a primer barrier (tie coat) is required... unless you use their "Clearcoat" or SB-112 resin.

I'd be interested to see if other non-blushing epoxies, such as Raka or MAS etc... interfere with paint drying even if cleaned up with a fresh water scrub etc.

I have noted that several on this forum have claimed no problems with paint drying on clean epoxy with West... (5:1 ).

RodB

[Bob Adams]

I have always used an epoxy based primer as an interface between epoxy and any type of finish. Never had an issue that way.

[Todd Bradshaw]

I never prime epoxy (generally WEST) and haven't had a problem yet, though I do wait a week or so, water-wash it first, sand it smooth, water-wash it again and paint. YMMV.

Dave, if you are planning to prime tomorrow, what happened to the little step in the process where you sand the epoxy so that it's actually smooth before paint or primer are applied? It makes a hell of a lot of difference in the fairness and quality of the final finish and leaving it out is one sure way to give a boat that "amateur construction" look.

[David G]

The solvent for the Parker Paint 1640 basecoat is Xylol (Xylene) and its so easy to slop on a couple of coats with a brush... sandable within 2-3 hours in warm weather. I have the number of the same product from Petit, I just need to find it.

System Three standard resin will cause paint drying problems 100% of the time because of the free amines that continue to be released from the epoxy... even after a few weeks. Thus, a primer barrier (tie coat) is required... unless you use their "Clearcoat" or SB-112 resin.

I'd be interested to see if other non-blushing epoxies, such as Raka or MAS etc... interfere with paint drying even if cleaned up with a fresh water scrub etc.

I have noted that several on this forum have claimed no problems with paint drying on clean epoxy with West... (5:1 ).

RodB

In the beginning, I used West... for many years. For the last 6 years, I've used RAKA. I guess I've been spoiled. I've never had any paint compatability issues - with or without primer - on either brand of epoxy. I used to go through every step I'd ever read about so that I'd never run into the dreaded *blush*. As time went on, I had some times where time was critical, and I risked having to redo it later. I haven't had to redo anything. Always in a climate controlled, but well ventilated, space. YMMV, of course.

[davebrown]

todd: this is about the third coat of epoxy. i have sanded at least three times now, and this was applied as thin as possible to simply finalize the epoxy undercoat. therefore, i am going to knock some off this morning with a fine sanding block, quick rub and rinse to clean it of dust, and give it a shot. i might consider going and buying some epoxy primer--can anyone recommend a brand?

with west and raka i have not had a problem. this is taps plastic 143, which i bought here locally for an exhorbitant price. so i don't have any experience with cure times on it.

[davebrown]

and btw, it is hard and set up this a.m., which is 24 hrs now. i realize the cure will continue at a more subtle rate now, but at least it is hard and sandable in the way green epox is.

[Todd Bradshaw]

In the future, you may find that it's better to sand the wood smooth, apply the glass and add all your filler coats with no sanding until the whole works is applied and has fully cured (unless for some reason there is something you need to taper out in your fiberglass layers, and even in that case, it's often better to let the filler coats themselves do much of the tapering and save the sandpaper until all the glass work is done). There just isn't much reason to sand epoxy smooth and then apply an additional coat on top, which then has to be sanded smooth again to really produce a high-quality surface. The end result of sanding between layers is no better (and often not as good) and you risk contaminating the surface in the process. Leaving the glass layers to fully cure makes it less likely for the sanding (or heat from sanding) to bruise the glass fibers. Also, if you seem to be sensitive to this particular resin, sanding it while green, even though it may be hard enough, is just asking for trouble.

[pipefitter]

You are going to want to sand regardless how 'smooth' it is. Especially with oil based primer. It needs a decent keyed surface being that this is a mechanical bond we are talking about here. Read the label on the paints. They will most often recommend the extreme to cover everyone and from that point, discretion is based on experience. Where some recommend 80-120 grit, an experienced painter will know how to get by with 320 grit by keeping the paper refreshed. 80-120 becomes 320 in short order when used on epoxy and glass.

People that get away with painting over 2 day old epoxy are either experienced or lucky. Spot repairs and touch ups, fine, but a whole boat is asking for possibility of problems. A few small fish eyes can cause issues after your boat gets wet. It really is best to wait a week.

A good practice is to pretend that there is no such thing as "No Blush" epoxies. I have seen changes in humidity cause strange things to happen with no blush epoxy regardless.

[KMacDonald]

I like Interlux Epoxy Primekote. You also need the thinner for it. Dont use Easypoxy on top of it though. Use Interlux Brightside.

[davebrown]

todd: i will keep that in mind for next build, which i am dying to get to. i sanded with 80 grit, then a fine block sander. then i primed it with valspar oil based primer.

this here boat lives in a trailer in a garage, so the worst thing that can happen is i have to repaint in a week or two.

i spent too much time overbuilding it. i want it the hell done so i can get to the next one. you know, the usual siren song with this affliction.

i wear a respirator and long sleeves with long pants and goggles when dealing with pox. hate it. hope to someday join cleek in never building with it again. in the meantime, my skills are gradually developing, just wish faster.

[RodB]

If you have any doubts of paint drying on epoxy, adding cobalt dryer to your paint is a good solution... especially if you cannot prime or are short on time. Some epoxies give off free amines that interfere with the driers in paint.

Also, if you apply paint and find it taking a long time to dry... you can apply another coat of paint with cobalt dryer added... and all will dry fine.

This was recommended to me by Tracy Obrien and I have found it to work very well. Tracy pretty much uses the Parker Paint 1640 basecoat as a primer on epoxy... (Petit 6164 Fiberglass undercoat is the same thing) but, if time is short and primer not an option, he adds Colbalt dryer. Parker Paint's 1640 basecoat is a "hot solvent" (Xylol) high build primer that is very easy to apply with a brush (two coats) and dries very quickly... and sands to a beautiful smooth finish... resulting in a very nice tie coat with additional protection of your surface. This primer fills all those little imperfections making for a very nice finish.

In the future, I am going to try System Three's SB 112 or Clearcoat when I want to paint without priming or am doing fiberglass boat repair. I also will consider trying non-blushing epoxies in the future such as Raka or MAS... but.. not West, cause is just costs too much. I will be interested to see if any of these have problems with paint drying on a properly prepared surface.

RodB

[KMacDonald]

I like S3 WR-LPU Linear Polyurethane Topcoat. It does not require a primer, is water based for easy clean up, covers great. Just paint right over cured epoxy. Tricky to get thinned right for flow out. It dries to a very hard surface.

[davebrown]

we'll see how it looks in the a.m. right now the primer is dry to the touch. i am excited to launch this thing, but i am more excited to start the next one.

[nickcan]

Hey Dave,

A question, if I may...

How did the Valspar product workout? I am restoring an 18' Bosarge Skiff (locally built near Mobile, AL). On my last project I used Rustoleum oil based paints as it was inexpensive and readily available. It faired well for its use... It was a low-budget boat and I couldn't see spending the $ per quart for a superior product.

[davebrown]

the primer went fine. i then topcoated with tractor paint, and i think it is valspar too: international harverster white, with massey fergusen red bottom coat. it's about $8 a quart, oil based, and tougher than the proverbial boiled owl. i have the second coat down on top of the primer, and thaqt is probably all i can get on before saturday, because tonight i will have to install oarlock blocks and oarlocks. i want to launch on sat because my brother, other reasons, has flown to cali from colorado. etc. thus far, it has all worked well.
maybe i can get thorne to post a picture for me...

[davebrown]

btw, the tractor paint is from tractor supply warehouse. it is a high gloss, and shows every error. my last boat was a 30 footer--looks good at 30 ft. this one is a 20 footer. i am hoping for ten footer on the next one.

[Thorne]

The only time I used the TAP epoxy was on a replacement centerboard covered with glass -- worked OK and dried rapidly, but I hated the blush problems. Will use Raka or Smith's next time...

Put the photos up somewhere, Flickr is good, and I'll post them if you can't. Get someone else to take photos for you from another boat -- just from the dock isn't good enough, and you'll want your launch photos to be good ones!

Here’s how to post photos on this forum:

First - don’t attach photos. Most web forums don’t allow it, and space limitations are the main reason why.

Second - Instead of attaching them to a thread, post the pics on the web somewhere. You have a free website area with any paid ISP’s email account, or use www.picturetrail.com (http://www.picturetrail.com), flickr, photobucket or other free image hosting service.

Once posted on the web, right-click the image to copy the URL (web address). Always test first by pasting the image URL into the window of a web browser and see if the image displays.

Remember, the IMAGE URL will end in .jpg, not .htm or .html. URLs ending in .htm are the page that the image is at, not the image location itself. If the image URL ends in other code, try deleting everything after the “xxxxxx.jpg” part of the URL to get it to display on web forums.

Third - once posted on the web, try this procedure while logged in to this Forum:

1. Click the “User CP” link in the browser window in the top left of the menu bar.

2. Click the “Edit Options” link about 1/4 of the way down the left column.

3. In the “Misc Options” at the bottom of the next page, select “Enhanced Interface” from the pulldown list.

4. Once this interface has been selected, in any “Reply” window you can click the “insert photo” icon --> a little yellow square icon with the stamp in the upper right corner, the mountains in the lower center.

5. Once the little dialog box titled “Please enter the URL of your image” comes up, paste the URL of the photo in the field.

If unsure of the procedure, test first by pasting the image URL into the window of a web browser.

[davebrown]

ok thorney. we'll see what can do. it looks pretty good so far.