Paint Compatibility

[moonie5961]

I posted this to another board, I'd love to hear y'alls opinion

I'm almost finished sanding topsides down, not to gelcoat- but to what I believe to be an old 2 part.

Is there any way to know whether it's a 1 or 2 part?

It is incredibly well adhered, and feels like gelcoat. I am down to gelcoat in some places, and in the others can clearly see a grey primer beneath a white topcoat. I think that this is a 2 part, which will be compatible with perfection. I still have to do some trim sanding along my rubrail, but at this point I am really anxious to test to see if the 2 part perfection I am going to use will stick.

At the areas where I have reached the gelcoat, there is some crazing visible. I'll fair this and the primekote should help, but this is another factor motivating me to test to see if the current level is adequate. As it is, the old paint doesn't show any crazing-and building off of this surface will eliminate alot of work, if the test goes well.

I am resisting the urge to rush the prep stage, as I have read time and time again that it's the stage that really matters. I do feel like it's important to know whether to proceed with fairing the hull or to continue sanding to gelcoat everywhere, though. Hopefully the latter step is unnecessary, and I've reached a suitable foundation to build upon.

My plan is to make a small test patch of prime-kote, then sand, then apply topcoat, then be astounded by the glossiest gloss that ever graced fibergalss. this sounds realistic, right? =-) Seriously though, if the test patch sticks, surely the rest of it'll stick.

Am I making a mistake by trying to avoid going down to the crazed gelcoat? If the old underlying paint is compatible, great. If not, I'll just keep on sandin'

Does anyone have opinions on watertite fairing mix? It's what interlux recommends and I don't feel comfortable mixing my own up. I guess I'll need to bite the bullet and do an epoxy job at some point or another.

Thanks in advance for any input

edit:
PS please forgive the novice question, I am very much wet behind the ears with all of this stuff, and the internet is my only resource for getting this right. I have researched this stuff to no end, but often come away from threads more indecisive than when I entered.
THANKS!

[The Froon]

There are far more experienced salts here than me, but I thought I would pass on my two cents as I am currently priming my Sea Sprite 23 with primekote - in preperation for perfection.

It would behoove you to follow the product directions as closely as possible, and aside from those directions:
- thoroughly clean / de-wax the hull prior to sanding, as you can end up sanding the wax contaminates deeper into the surface
- a good paint job is 85% prep work...feels like endless prep
- the primekote product is designed for perfection, and it would be good to prime prior to your top coat regardless; primekote is also a good primer for crazed surfaces (above the waterline)

...I am sure others will add...

Brian

[Shoalcove]

Typically, the test for paint compatibility is to crosshatch a small area of existing paint with a razor and then tape a rag soaked in the solvent for the new paint to the area. Wait for a bit (an hour perhaps) to see if the paint is affected. If no, you're good to go!
Most companies will advise you to prime the whole thing if you aren't recoating their product.
I've never used Watertite but a friend is doing a deck repaint and likes it just fine.
I agree 100% with everything Brian posted. I painted my boat last year and rolling on paint was the quickest and easiest part of the job.

[Tim]

Click here for a description of compatibility testing procedures from the Awl-Grip website. The basic process applies to all paint systems.

When in doubt, remove the old paint. A good paint job is all about the prep and substrate.

[Rachel]

A couple of thoughts that came to mind as I was reading the thread:

1) Watertite is a branded product (used to be "VC" brand; now it's Interlux). I got the feeling from reading your post that perhaps you thought you were supposed to come up with something on your own that was "water tight." Watertite is a fairing compound that comes in two parts which you mix together (x-sized lump of blue; y-sized lump of white) and then spread on.

2) Brian mentioned de-waxing. Although any surface should be properly prepped, I think the de-waxing applies to a gelcoated finish and not a painted one. If my thinking is correct, and your current paint ends up being compatible with your new paint, you shouldn't have to follow the exact same de-waxing procedure as you would on the gelcoated sections (i.e. the Solvent Wash 202 and the very careful use of a new section of rag for each area). I believe the de-waxing is for mold-release wax, which (amazingly) can remain on gelcoat 40 years after the boat was built.

Rachel

[moonie5961]

Great responses! Thanks!

Rachel,
The reference to mixing my own compound was my explanation for not mixing up an epoxy/cabosil/microbaloon combination like I have read about on here, I was just going to buy the can of watertite.
I was just not sure if the pre-made watertite would be OK or if I should get awlfair (here again, compatible?) or man up and mix up some epoxy/cabosil/filler.

In preparation for sanding, I was paranoid so I cleaned my topsides multiple times with acetone, followed by TSP, then solvent 202, then a fresh water rinse to check for beading. It made a significant difference, at the end of the process, water cascaded off- as opposed to the waxy beading that occurred before cleaning.

To anyone considering the job that reads this, I (in my novice opinion) would always recommend cleaning, gelcoat or previously painted, whatever. It is really an easy step, and alot of times, you never know if the PO did in the past. Plus, I think that oil residue and in my case, road grime from the trucking would have been ground into the gelocat.



Tim,
That is exactly what I was looking for, thank you!

Shoal,
Thanks! Your (and awlgrip) recommendation for cross hatching and the solvent is exactly what I'll do. I'm glad that your friend had a good experience with watertite, it sounds like it'll be easy to work with.

Brian,
I agree with everything you said! I was planning on using primekote, already de-waxed, and you are absolutely right about the prep seeming never ending. I'll be glad when there is some visible progress-even in the form of primer on the hull. Doing all of this work and not seeing noticeable results can be really disheartening.

As always, I feel much better after coming here, thank you all for your thoughtful and knowledgeable advice

[moonie5961]

Well, I did the compatibility test by taping a saturated rag with Interlux brushing reducer 2333 to the hull. I was worried that I wouldn't recognize the "softened" paint if it was indeed incompatible, but that wasn't an issue. It is amazing how aggressive the chemicals in the 2333 must be! It completely dissolved the old paint-which was obviously not 2 part like I had hoped. It was very obvious that I needed to sand further. I was a little bummed, but it is really satisfying to get down to original gelcoat instead of just varying degrees of white.