Spot priming with self etching primer?

[kgronseth]

Hi,
I tried to do a search but couldn't find exact answer to my question. I just bought a 1968 Lund S-14 and would like to re-paint the upper part of the hull and the inside of the boat. I have done some some research and think I understand that I can sand the parts that have the original paint and that I need to use a self-etching primer on the bare aluminum parts.

My question is, is it ok to get some self-etching primer on the original finish? Using a rustoleum type spray can self-etching primer I can't see how I won't get overspray onto the orginal finish. Or do I need to get self etching primer in gallon size and use a brush to be more precise? The inside has a lot of small (1 inch type) scratches in the original finish. I wasn't sure if spot spraying self-etching primer over the orginal finish would cause any adhesive issues with the top coat.

I would prefer not to sand the entire boat to bare aluminum. I don't think I have the time for that. I have attached a picture as an example of the outside of the hull.

Thanks for any advice!
Kyle

 

[Woodonglass]

Re: Spot priming with self etching primer?

Here's how I recommend you paint your boat...

For aluminum boats use Rustoleum's Self Etching Primer on ALL bare aluminum spots and Rustoleums Bare Metal Primer on the rest or just sand smooth the existing paint if it is still adhering well. If you have Deep sides you may need to adjust. I recommend Rustoleum's Topside Primer. IF your boat is NOT left in the water for MORE than 3-4 days at a time, this will work fine. This is NOT for boats left in the marina for the season.

This is for Roll n' Roll Application

Final sand and wipe down with acetone.
Two coats of Primer. Roll n' Roll technique is the same. Thin coats!!!

2 cups Paint
1/4 cup of ACETONE
1 oz of Valspars Acrylic Enamel Hardener (1/8 cup)

Wet roller with paint an roll out about 4-6 sqare feet. If you can HEAR the paint you are rolling too long. Put the first roller in a Plastic bag and use another roller. wet it out but wring out almos all of the paint and then Re-roll the area you just painted. Use a very LIGHT stroke and the paint should lay down with NO Bubbles!. Put this roller in the bag and use the other roller again. Repeat this process untill the boat is painted. Always do the re-roll with a damp roller with very little paint in it and LISTEN. You will hear the sound that lets you know when it's time to stop. It's kind of a sticky sound.


For Spraying.

Final sand and wipe down with acetone.
Two coats of Primer. HVLP Sprayer with 1.2mm TIP Thin coats!!!

1 qt paint
1 1/2 cups of Acetone and 1/4 cup of Mineral Spirits
2oz of Hardener (1/4 cup)

This yields two coats of Paint.
Shoot first coat in the morning.
Wait 4-5 hours.
Wet sand with ScotchBrite Pad LIGHTLY to knock down any nubs or bugs.
Dry.
Tack cloth off with Mineral Spirits.
Dry.
Shoot second Coat.
Let dry over night
Repeat wet sand and Tack cloth
Shoot 3rd and 4th coat if needed.

​

 

[kgronseth]

Re: Spot priming with self etching primer?

Thanks for the great information!

So, when using the Rustoleum Self-Etching Primer I can only find it in spray form. When spraying the bare aluminum spots, I am sure I will have some overspray to the original finish that I will have sanded down some. Will that be an issue?

The reason I ask is I read somewhere that the self-etching primer may cause adhesive issues for the top coat it if is applied to the orginal finish. Even though I am only doing spots, I think some of the self-etching primer will get on the orginal finish and I would hate for that to be an issue.

 

[Woodonglass]

Re: Spot priming with self etching primer?

Nope, It should NOT be an issue, But like I said you should also prime the entire boat with the Metal Primer. Some say you can just paint over the Old Paint but a LOT of guys on here that have done that have had adhesion problems. I HIGHLY recommend the primer.

 

[kgronseth]

Re: Spot priming with self etching primer?

Great! Thanks again! This site is such a great resource.

Also, this boat will be trailered and stored in the garage when not being used so the bare metal primer over the original finish shouldn't be an issue.

A couple of follow-up questions:
1. To clarify, the bare metal primer should just go over the original finish and not over the spots I used the self-etching primer on or do I do the self etching primer and then the bare metal over original finish and the self etching primer?
2. Would the process be the same for the inside of the boat?
3. What would be the best way to remove the original Lund decal?

Thanks again for your advice.

 

[Woodonglass]

Re: Spot priming with self etching primer?

Prime the ENTIRE Boat with the Bare Metal Primer. Inside and Out. Decals are NOT easy. They Make "Decal Erasers" Google it!

http://www.aircraftspruce.com/catalog/cspages/decaleraserwheel.php

 

[Yacht Dr.]

Re: Spot priming with self etching primer?

My question is, is it ok to get some self-etching primer on the original finish?

Your painting the whole thing..so the answer is simple ..

Prep your paint area ( what your end spray/application will be ).
Spot prime your repairs or bare alum ( yes the chromate or chromide or alumiprep/alodine/primer overspray will be ok If your already prepped )

Preferably prime the whole spray paint area. If not..then spot prime your repairs/bare spots.

You Prime Everything you Paint .. Everything !! ( spot prime your repairs..then primer before you paint ).

YD.

PS. Woody is right .. Prime all first..then paint ..
PSS. or risk doing it again ..