Universal clear over aluminum engine parts

Toolin

Toolin

Promoted Users
I plan on clear coating a number of aluminum engine parts. Some I may blast and others I will not because I don't want to introduce any dust to the engine.
I've read a number of posts regarding the subject and I've seen a number of replies specifically from Jim C where he recommends using an adhesion promoter with a little catalyst. I am not familiar with any 2-part adhesion promoters so I suspect there may be a universal type product that can be added to catalyze the product. Someone please enlighten me?
 
The SPI adhesion promoter is the best I ever used. Jim I believe recommends using a small amount of clear catalyst in the ad-pro prior to clearcoat.
Clean, clean, clean on the aluminum.
 
It's in the SPI tech manual. The ratio is 5:1. It says to use 6501, but I would be willing to bet any SPI (urethane) activator would be fine. Might want to call on that one.
 
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When talking to Barry is comments where aways "Yes you can do it" and "Yes it will eventually fail" I have done it to all may engines but the last one I epoxy primed the aluminum then painted it. If it is a part that has hot exhaust gases (like an intake with the heat risers) my experience is that area will yellow and turn a light brown eventually. I have not had anything actually fail yet.
 
hmm missed this one. you can use any of the hardeners in the adpro. its basically like adding cat to basecoat. the only one i dont like to use to base or adpro is universal just because its higher in solvent than the others being a 1:1 clear. typically prod, euro, speed clear cat all works well and i use them in base every day.

i have never had an issue with failures. i am typically going over polished aluminum. is the adhesion as good as prepped metal with epoxy...absolutely not BUT i have never had peeling issues either. i am usually doing this on things like chrome or polished alum motorcycle wheels, etc. if you have it prepped in some way then your adhesion will be even better. a hot engine may be another story but i dont see an issue except in the super hot exhaust areas like jim mentioned. everything will discolor there which is why anything super hot will get painted black.
 
So on something your trying to maintain the shine on prep would just consist of cleaning very well I assume? The ad pro is doing the rest.
 
Thanks Jim C for chiming in.

Everything I want to clear coat will be blasted or brand new castings, i.e. intake and heads wiped with 700, My understanding is I should be fine provided things don't get hotter than say, 400F using SPI-UC with SPI 600-4 AdPro.

Question: Does the time once the AdPro has been applied before spraying top coat change as specified in the SPI tech manual (30-60 minutes) change if using a catalyst?
 
If anything it may lengthen it a little.

350-450 is roughly the max temp i have found using regular clear or ss. Thats before it fails. If using ss then many colors will change long before that. Yellows are quick to get darker as they get hot then they lighten as they cool.

Blast, spray with 700 then blow dry. Do not touch with a rag
 
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