Painting questions

[SailingWebGuy]

Hello!

I recently starting working for a very large yacht manufacturer. My department does a lot of detailing in the engine rooms. The painting procedures that we are using seem to be quite different than anything I've learned in the past They also seem to vary from boat to boat.. So I'm posting to SN to see if there may be a better procedure than what we are doing.

The paint we are using is a 3 part Awlgrip product...paint, activator, and initiator.

I should also mention that I'm posting because the last few engine room floors we've painted have given us a bit of trouble. I think we are not prepping the surfaces correctly and it's doubling our efforts.

Here is the procedure we used on the last problematic paint job. We had the second coat of paint peel up when we went to spot sand a few blemishes that appeared.

1. Sand with 150 grit.
2. Sand with 320 grit.
3. Remove dust, clean with acetone, wipe with tack rag.
4. Paint.
5. Sand with 320 grit.
6. Sand with 600 grit.
7. Remove dust, clean with acetone, wipe with tack rag.
8. Paint.

My initial thought was that sanding with 600 grit might be too much for the paint to adhere well. I know that step 7 was done correctly so there wasn't any dirt or oils on the surface.

What are your thoughts or comments?? Any tips would be greatly appreciated.

[GaryHLucas]

I suggest the problem may be the acetone used for prep cleanup. On new fiberglass you are probably going to have a mold release present. Possibly PVA, Poly Vinyl Alcohol or even a silicone. I'll bet that Awlgrip sells a prep solvent that they recommend for new fiberglass that will be much more aggressive at cleaning Probably way more expensive, and worth every penny!

Gary H. Lucas

[Siamese]

What is the engine room floor surface? If it's created in a mold and the part you're painting was in contact with the mold, then yes, we'd expect mold release wax to be present.

Or...if the floor is the opposite side of the fiberglass...opposite the mold, then there shouldn't be any mold release present.

[Faster]

The wash prep we were advised to use prior to Awlgrip was a noxious product called Tumbler...

[SJ34]

I think 600g is too fine, 220g should have been fine enough to give a smooth finish and good adhesion.

[tommays]

545 primer or =? cause its not gonna stick without it

If you hit the window < 24 hours there is not that much to be gained by the sanding in between coats

[SloopJonB]

600 grit is not too fine - that is standard practice for show quality paint on cars. You only need a lack of gloss to promote adhesion.

My bet is the acetone, esp. if you have been using "gun cleaner" or other recycled / cheap acetone.

Use the recommended prep wash, the new multi part paints are insanely sensitive to anything that is less than perfect - the price you pay for their incredible qualities after curing.

[poopdeckpappy]

One thing you should keep in mind is to use a surface clean prior to step 1 to remove any waxes,oils and grease so your not melting (basicly) them into the surface when you sand and then sand ,vac and wipe again prior to step 5

0340 is good for this as it wont damage the finish like a de-waxing or degreaser solvent will, if it's cured enough to sand it's cured enough to wipe with 0340; Also, 600 does sound a bit much, maybe cut back to 320