what went wrong?

[ziguan]

sorry, English is not my native tongue.

was gonna pressure wash it before flipping.
then saw paint started falling off. I was so sad/mad. anyone have any idea as what might went wrong?

old/orig paint was removed all the way to aluminum.
self etch primer
two layers of RUST-OLEUM marine metal primer
two layers of RUST-OLEUM marine topside

as far as I can see, only the topside paint was falling off, or could be scraped off somewhat easily.
metal primer stay there really really really well. also, what I don't understand is. paint in the area that I haven't try to remove. look very nice and hard.

between each coat:
S/E primer -> metal primer (1 1hr) -> 2nd metal primer ( 1week ) ->1st top side (two weeks) -> 2nd top side (two weeks)

 

[SumDumGuy]

Re: what went wrong?

Bummer, my guess would be bad paint or contamination.

Hopefully someone with some actual knowledge will really know.

 

[KnightWolf]

Re: what went wrong?

I do t have any advice just wanted to say that's really sad that it happened. That sucks.

 

[Woodonglass]

Re: what went wrong?

What were your temps and humidity at the time of application? What method of application? Spray? Brush? Roll? Did you Thin the paint if so how much and with what?

 

[chconger]

Re: what went wrong?

Smarter people are on the way. Until then, you have me;

I had a deck I painted (2 part polyurethane) on my sailboat that lasted 10 years. Then I took a pressure washer and held it close, and... vrrrrooop; paint gone back to primer.

Beware of pressure washers, they are the devil's toy.

 

[ziguan]

Re: what went wrong?

What were your temps and humidity at the time of application? What method of application? Spray? Brush? Roll? Did you Thin the paint if so how much and with what?

did it in June/July. between 85 F - 90 F. didn't pay much attention to humidity. pretty much did it whenever I could find time. 1st topside no thinner. roll and roll. then saw lots roller marks. was thinking. maybe too thick? thinned 10% for the 2nd coat. then turned out it left so many bubbles. mixed it with another Qt. so I think it was about 5% thinned at the end (I really think for this paint, I shouldn't have thinned it).
but looks like the problem is between the metal primer and the 1st topside?

 

[KnightWolf]

Re: what went wrong?

I see it looks like you waited a week between priming and painting what prep work was done before the actual paint was applied? Or am I misunderstanding that? A lot can happen in that amount of time. My guess would be prep before painting.

 

[ziguan]

Re: what went wrong?

I see it looks like you waited a week between priming and painting what prep work was done before the actual paint was applied? Or am I misunderstanding that? A lot can happen in that amount of time. My guess would be prep before painting.

I sort of wet sand it a little. but because I've spent months preparing the aluminum hull itself. everything was so smooth, didn't need much wet sanding at all. so, after a nice wash, dried over night. applied 1st topside the next day.

 

[jbcurt00]

Re: what went wrong?

What was the recommended topcoat window after priming?

A week may have been long enough for the primer to cure sufficiently that a good sanding tooth was needed to get the topcoat to stick..........

The sanding between primer & finish paint is also prep, and equally important to all other prep steps.

 

[zool]

Re: what went wrong?

There are many reasons for delamination, but from what you said, heres my take.

1, as stated, pressure washing removed paint, but if properly applied, it should hold up mothe than that.

2, You said you wet sanded a bit, then washed it. Unfiltered water can contain contaminates, which is why you should use a solvent based surface cleaner (wax/grease remover) or at least alchohol right before aplying finish.

3, if you didnt sand with the recommended grit for the system youre using, you may have made it too smooth, and failed to get a decent bite for the topcoat.

 

[Woodonglass]

Re: what went wrong?

I agree with the above. You did not mention anything about sanding between finish coats, and or the wipe down with any chemical cleaner.

 

[ziguan]

Re: what went wrong?

thank you very much for all the replies.
I guess you are correct, I should have cleaned it with chemical cleaner. instead of water.
lesson learned

 

[Bondo]

Re: what went wrong?

thank you very much for all the replies.
I guess you are correct, I should have cleaned it with chemical cleaner. instead of water.
lesson learned

Ayuh,.... I'm guessin' you didn't sand it enough with the week long waits, between coats,... zool's #3,...

Probably should have done a 320 sandin' to dull it between the coats,...

I never chemical wipe with Rustoleum, myself,...

 

[ziguan]

Re: what went wrong?

Ayuh,.... I'm guessin' you didn't sand it enough with the week long waits, between coats,... zool's #3,...

Probably should have done a 320 sandin' to dull it between the coats,...

I never chemical wipe with Rustoleum, myself,...

I did not sand the self etch primer, but the metal primer sticked to it very well?
since I will have to do it all over again.
what will be the bullet proof way(or there is none?) to do it?
sand the metal primer before the topside? or just put it on when the metal primer is 80%(?) 90%(?) dry?
one thing that's really puzzling me is. some spots on the side of hull. paint(every layer of them) are sticking very well. for the hell of it. I just can't remember what I have done differently at those areas.

 

[Woodonglass]

Re: what went wrong?

When painting it's very important to not get contaminants on the underlying coats of paint. It's also important to sand the previous coat so the next coat has something to "Bite" into. I would Not wait a Week between coats. I would recommend applying the SE primer, let dry for 2 hours then do a light buff with a 3m Pad to knock off the nubs then a wipe down with a Damp, not wet, rag with Mineral Spirits. Let dry for 10 mins then apply the first coat of Metal primer. Let it dry for 4-6 hours, light Sand with 320 grit, again wipe down with Damp rag of Mineral spirits being careful NOT to touch the boat with your bare hands. Let dry for 10 Minutes then shoot the next coat. Let second coat dry over night. Next Day start to apply the color coats repeat the above process, and apply 2-3 coats of color with 4-6 hours between coats. Then let the boat set and cure for a week before doing anything. I would NOT use a power washer on it for at least 6 months if ever Especially if you are not using the hardener in the paint.

 

[ziguan]

Re: what went wrong?

When painting it's very important to not get contaminants on the underlying coats of paint. It's also important to sand the previous coat so the next coat has something to "Bite" into. I would Not wait a Week between coats. I would recommend applying the SE primer, let dry for 2 hours then do a light buff with a 3m Pad to knock off the nubs then a wipe down with a Damp, not wet, rag with Mineral Spirits. Let dry for 10 mins then apply the first coat of Metal primer. Let it dry for 4-6 hours, light Sand with 320 grit, again wipe down with Damp rag of Mineral spirits being careful NOT to touch the boat with your bare hands. Let dry for 10 Minutes then shoot the next coat. Let second coat dry over night. Next Day start to apply the color coats repeat the above process, and apply 2-3 coats of color with 4-6 hours between coats. Then let the boat set and cure for a week before doing anything. I would NOT use a power washer on it for at least 6 months if ever Especially if you are not using the hardener in the paint.

when you said "4-6 hours", it really depends on the temperatures and humidity at the time. could you please give me some ideas as how dry it should be? 90%? 99%?
I always thought it's better to let each coat fully dry first. but looks like that's not a good idea, why?
I have always wore gloves when doing the cleaning/painting. so it's got to be either the missing of chemical cleanner or sanding.

 

[pauloman]

Re: what went wrong?

how long from the application of the last coat to when you pressure washed it?

the one hour wait between primer 1 and 2 worries me. Not enough time for the solvents to flash before being sealed under the next coat (just a guess!)

Paul Oman - MS. MBA
A.K.A. “Professor E. Poxy”
Internet Epoxy Confederation (IEC) Homepage
epoxies since 1994
Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)

 

[Woodonglass]

Re: what went wrong?

The instructions I gave were for Paint with added hardener. If NO hardener then there's a 24 hour window between each Color coat. SE primer Flashes very quickly as does the Metal primer. It's recommended to recoat in that time frame. For color coats with hardener the same window applies. Without hardener then 24 hours is recommended. It's best to try and avoid touching the boat with anything other than the wipe down cloth and then shoot the paint as soon as the wiped down solvent has flashed off. That's how I was taught and How I did my boat and I've never had any issues. Contaminants are usually the biggest problems incompatible paints being #2.

 

[ziguan]

Re: what went wrong?

how long from the application of the last coat to when you pressure washed it?

the one hour wait between primer 1 and 2 worries me. Not enough time for the solvents to flash before being sealed under the next coat (just a guess!)

Paul Oman - MS. MBA
A.K.A. “Professor E. Poxy”
Internet Epoxy Confederation (IEC) Homepage
epoxies since 1994
Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)

S/E primer ->1 hr -> metal primer -> 1 wk -> 2nd metal primer -> 2 wk ->1st top side -> 2 wk -> 2nd top side

I power washed it two weeks after the 2nd top side.

 

[ziguan]

Re: what went wrong?

do you mean if within the window. no sanding is needed but wipe with solvent is needed between each coat?

the two top(color?) coat I have put on stick very well to each other. but they could be peeled off from the metal primer every easily. I did the same to each coat(including primer and topside), which was washed with water, soap, then lightly sand(only spots with roller marks etc).