What the heck happened?

[420TEE]

Having read several posts about using Rustolem to finish a boat I gave it a try. Took a scrap piece of plywood from the kit, sanded an area and sealed it with thin epoxy sealer. Let that cure several days, sanded it and sprayed a couple of light coats of red gloss Rustolem. Let that dry at least 8 days. Today I sanded the paint lightly and put a coat of the thin epoxy on it. Immediately the epoxy started to form little rivers on the surface, much as if I had put two coats of Turtle wax on the paint instead of sanding it. It's now cured and looks like a satellite image of a river basin in red. Thank St. Elmo that I didn't do the whole boat without testing it. What the heck could have happened? :confused:

[unclecrash]

Two part acrylic urethane you want a good strong fuel proof paint job.

[keith S]

Epoxy does not like to ahear to painted surfaces. It prefers the "raw" material so that it can bond with/into the natural material. Any thing between the epoxy and the material just acks as a block and will not allow it to stick. It will peel off the paint and leave a bare spot on the wood.

[420TEE]

That's interesting since I got the idea from posts on the aircraft-fuel site. A gentleman who is obviously far more experienced than I says he has often coated well dried Rustoleum with thinned 30 minute epoxy and it has worked well as fuel proofing. :confused: I don't know anything about acrylic urethane or where to get it.

[unclecrash]

Its not cheap and its has a catylist its dangerous to use supose to be sprayed by proffesional with air supplyed resperator. But I just get the good charcoal one from paint store. A regular auto paint store sells the paint. I put it over an epoxy primer which has a hardener another dangerous paint but it must be put on right because you do not sand it. The paint has to be put over it within several days or it could blow off in sheets. But when the paint and primer dry its a very hard finish. I understand it to be somewhat fuel proof up to 30% so you try no to spill when filling the tank. The burn fuel will not harm the paint . I just splash a bit of water on the boat when filling. Dave

[unclecrash]

That's interesting since I got the idea from posts on the aircraft-fuel site. A gentleman who is obviously far more experienced than I says he has often coated well dried Rustoleum with thinned 30 minute epoxy and it has worked well as fuel proofing. :confused: I don't know anything about acrylic urethane or where to get it.

Are you sure he is putting thinned epoxy over top because denatured alchol will eat into a lot of different paints. some how I got a little red paint scuff on my boat and used a bit of alchol to remove and I could see just a bit of yellow on the rag from rubbing it. Dave

[Massey]

This sounds kinda like the epoxy attacked the paint and you have what is called "lifting" This river bed you describe is it from the paint itself making the little channels (looks like a mountain range from space) or did the epoxy just not adhere and just pull away from the painted surfaces like when you put water on something oily? If you have lifting you will have to sand it all down again and start the painting process over. Lifted paint will provide little to no protection to your boat and will not look very good. Some times you can even get lifting from the paint itself. Some paints cannot be recoated durring certain times. This is especially true with enamal type paints. Enamals go through 2 stages of drying, the first is where the solvents evaporate from the paint leaving a finish that can be touched but marred easily, the second stage is the hardening stage (this is where you cant recoat). Durring the hardening stage your paint is becoming a hard shell around your model. Once an enamal paint is cured completely or before it gets to the hardening stage you can apply a second or 3rd coat(read the can for the application times they very based on the brand/type). Also dont mix laquer and enamal paints, they are not compatable and will cause peeling and/or lifting. If you are painting a model that has been painted before and you dont know what kind of paint was used sand the old paint lightly and apply VERY thin coats of primer of the type of paint you plan on using. The primer may cause lifting due to incompatable paint types but there is alot less chance of the primer doing it then the paint. The primer once applied will act as a barrier to the old and new paints so lifting may not happen. (sand lightly between coats if the paint is allowed to dry completly and make sure you are not in the hardening stage).

most paint cans will not tell you that the paint is in the drying or hardening stage but will say something like: Apply thin coats and allow to dry for 10 minutes between coats. Can be handled after 30 minutes but Allow 48 hours to completly dry.

The 10 minutes is to allow enough drying to minimize runs and the 30 minutes is when the paint stars hardening which will take about 48hours to run its course (times very based on temp and humidity). Always scuff the paint after it has been through the hardening stage so that the new coats will have a surface to adhere to. Keeping these things in mind when painting your boat/plane/or whatever will help you come out with a better finish every time. Hope this helps

Massey

[420TEE]

Dave, Yes he definitely states that he finishes the well dried Rustoleum with epoxy thinned with den alcohol.
Massey, The channeling was the epoxy not adhereing. It happened immediately when I applied it. Interesting effect, but not what I want on the boat. I'm testing a different paint now. I'll know in a week or so. Maybe I'll just go back to the way I did it 40 years ago and go to the hardware store and buy a couple of small cans of oil based enamel and forget all the modern mumbo jumbo. :rolleyes: Also it's new construction, bare wood not yet sealed or painted.

[unclecrash]

I would seal it before you paint or prime that way if the gas oir nitro gets through the paint it will not get to the wood. I dont understand how you get a nice clear coat with the epoxy over the paint are or were you brushing or putting it through a spray gun? Dave

[420TEE]

Dave, I intend to seal the whole thing with thinned epoxy first. The other gent says he applies the final thinned coat over the paint with a good quality artists brush. I just slapped it on as a test with a disposable brush. Anyone know how fuelproof good old spar varnish is? My 30 year old Dumas kit suggests using that as a sealer.

[LtDoc]

...sounds a lot like the old 'crinkle' finish on some metal cabnets (and one or two of my boats!). 'Rustoleum' isn't the only thing this happens to, and testing stuff before use is a VERY good practice to get into (need to take my own advice too). Not on boats, but I've had the same thing happen when 'mixing' different types of paint/varnish/glues and whatever. Most of the time I have no idea of why it happens or if it will happen. Once or twice it was a complete suprise since 'everything' was the same brand and was supposed to work well together.
So, while 'having company' in your missery isn't exactly the best idea in the world, take some comfort from it... THEN TELL ME WHY THIS @#$& HAPPENS TO ME! LOL.
- 'Doc

Wat a minute! I know 'why' it happens so tell me before I do it again!

[420TEE]

'Doc, You'll be the SECOND to know! :p

[unclecrash]

Could be water prob. could be oil the only time ive had reactions is when i tried to change over from one type of paint to another. Dave