Rustoleum Self Etching Primer not Sticking

I have been sanding the paint off of an old 1436 Alweld I recently bought. What a job it has been! I will never completely strip another boat as long as I live. To prep for the painting I rinsed the boat, then used 80 grit sand paper to scuff the surface of the entire boat. After that I thoroughly washed the boat with hot soapy water and a soft bristle brush. I then applied a mix of vinegar and water.

After the boat dried, I applied a light dusting of the primer. I then finished with a second coat that completely covers the aluminum but just barely. Well, it's been about 3 and a half hours and I can still scratch the primer off with my finer nail.

The directions on the can say the surface can be sanded after 3-4 hours, but this stuff would come right off it I touched it with sand paper. Any tips would be very appreciated. Does it just need to cure longer? A lot of people seem to swear by this stuff but I'm not having much luck. Anyway, thanks in advance.

Self etching just needs a light translucent coat to bond to aluminum. Then paint over top. I did a 16' boat with 3 cans and people said I used too much. Lol. I let it cure a couple days before I painted but that was winter so the garage was cooler.


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Well, crud. I put the first coat on super light, but there was quite a bit of bare aluminum so I put on a second coat to cover all the aluminum. I really don't wanna scrape this boat down again. It has been a pretty big task.

Walk away and let it sit. Look again tomorrow.


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oh no

a "light dusting" or "very thin coat" will not work !!
it is like the paint is on its way to drying as soon as it leaves the can.
think of the spray granuals as "safety in numbers" - - - you must put down
as many granuals as possible to achieve the wet coat - but not so wet that it runs or drips.
temperature and humidity will affect the application and drying times
This information is provided for the climate to be 70*f and 50% humidity.
cooler temps means more waiting time
warmer temps mean less waiting time

try to understand this - - - a "wet coat" that is too wet is where you apply too much
paint on a vertical surface and it will sag, droop or run down in small rivers.
a "thin coat" is still a wet coat - just not so much that it will run down a vertical surface.
a "too thin" coat will have a powdery, granular feel to it when it dries on the surface
because it has already started drying before it lands on the surface.
no amount of "waiting for it to dry" will help - it has already dried and must be sanded off.

in 95% of my posts, I strongly advocate:
Read, Understand and Follow the instructions on the label

I have a can of Rust-Oleum S.E.P. here in my hand now and it says . . .
shake the can vigorously until the ball rattles - continue for another minute and shake often during use.
hold 12-16" above the surface, spray in a "steady" back-and-forth motion, slightly overlapping
the previously painted areas. very important note - a "thin" coat is not a "dry" coat.
2 or 3 "thin wet coats" are far better than one thick wet coat in any kind of coating. (paint, primer, varnish, etc).
this particular primer can be recoated after 5 minutes for 2 or 3 coats.
the product must dry for 15-20 minutes before wet sanding with #400 paper or 3-4 hours for dry sanding.
note: the sanding process is necessary to remove any "over spray" or "flashing" that occurs when spray painting.
Dry powdery paint serves no purpose at all and must be removed. [and do it again].
also, the sanding provides a "tooth" for the top coats to properly bond to the primer.
so if the primer is not properly bonded to the surface - it is only a matter of time before adhesion failure sets in.
note: a vinegar or OSPHO etching wash is only good for BARE METAL - not painted surfaces.
so any primer that is applied - must be sanded, as per the instructions on the product you use.
existing paint that is not peeling or flaking, can be painted over after the abrasion process.

if you are not familiar with the basic painting techniques, practice on a similar surface
in the vertical and flat positions until you can do it with a "thin wet coat" and it will not run.

""steady" back-and-forth motion" means just that - - - slow and steady: a consistant distance and speed
to achieve a "thin" - "wet" coat without running and not so dry that it flashes or granulates on the surface.

jus my Dos Centavos

Read, Understand and Follow the instructions on the label of all products you use.
Pay particular attention to the safety notes and heed the warnings accordingly.
any rags used in the prepping/painting process that have solvents, oils or paint on them,
should be layed out in the open to completely air dry prior to discarding them.

Note: it has been discussed in other forums that Self Etching Primer
is designed for bare metal only . . . . if it goes over a painted surface,
there is the inherent risk of the SEP tunneling and burrowing under
the existing paint to create an avenue for corossion.




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Johnny,

Thanks for your well written response. I believe you may have hit the nail on the head. Two days later, and the primer can still be easily scratched right off. I'm just not sure why so many people recommend this primer if it is so temperamental to work with. I am no professional painter, but I am great at reading and following manufacturer directions. I initially used a light coating because many people from forums, youtube, etc. suggested so. Oh well, looks like I will once again be stripping this dang boat.

On a side note, I ran out of the Self Etching Primer about half way through the inside of the boat and wound up finishing the prime with Rustoleum "Aluminum Primer." It comes in a can and can be bought at Home Depot. So far I have to wonder why nobody recommends it. The product covered the aluminum much, much better, and a single can lasts about twice as long as the Self Etching Primer, and only costs about $1 more.

After a few hours of drying, I gave it the finger nail scratch test, and it didn't budge. I decided to see what it would take to remove it, so I started sanding lightly with a scotch brite pad. The new primer held up very well. The directions say to allow 48 hour cure, so I will have to report back on how well this new primer accepts and holds paint. Thanks again for the info.

Hi, I also had better luck with the brushed on aluminum primer. It provided a better coat and seemed to hold up to more abuse then the spray.

Lion - you do not have to "strip" your boat again..... just wet sand
to remove all the loose stuff that is not adhering.

up in the top right corner of this forum, there is a "search" feature......
use this to address any of your concerns prior to jumping into an unfamiliar area.

also - in your spare time, go back and read through the hundreds of threads
about prep and painting - - - - I have 40+ years as a painter and have written several articles
about priming, painting and basic woodworking and metalsmithing.

on small areas (less that 1'x1') I will use the spray primers.
larger than that, I will break out the brush-on type.
I also paint most everything with a brush - that is just my way.

once you use a few products - you will find something that you are comfortable with.
practice - practice - practice !!! I advocate trying a new product on scrap material
prior to putting it on something you may have unsatisfactory results with.

in the future: if in doubt - PLEASE ASK !!! PHOTOS will help us help you.

Welcome to Tin Boating !!

Johnny said:

Lion - you do not have to "strip" your boat again..... just wet sand
to remove all the loose stuff that is not adhering.

up in the top right corner of this forum, there is a "search" feature......
use this to address any of your concerns prior to jumping into an unfamiliar area.

also - in your spare time, go back and read through the hundreds of threads
about prep and painting - - - - I have 40+ years as a painter and have written several articles
about priming, painting and basic woodworking and metalsmithing.

on small areas (less that 1'x1') I will use the spray primers.
larger than that, I will break out the brush-on type.
I also paint most everything with a brush - that is just my way.
alum primer.jpg
once you use a few products - you will find something that you are comfortable with.
practice - practice - practice !!! I advocate trying a new product on scrap material
prior to putting it on something you may have unsatisfactory results with.

in the future: if in doubt - PLEASE ASK !!! PHOTOS will help us help you.

Welcome to Tin Boating !!

Click to expand...

Hi I came across this post while searching for some answers. I used the same Self Etching Primer, I'm def a rookie and I'm not sure if I used too much? 1 can got a "thin'' on my boat so I used a 2nd can, then a 3rd can I used to top off some areas that seemed to be lacking. Whats my next step? I'm told I don't sand this self etching primer, that I find a primer for my self etching primer... before I paint it.

I figured I'd have to sand the self etching primer then just apply the marine paint. Can you provide some insight on what I should do next? Boat is 100% covered with self etching primer (Rustoleum).