What should I have done? I degreased my newly welded shiny steel parts. The following day, I painted them in cellulose primer. Now that
they're dry, the primer is peeling off in sheets.
Tomorrow, I want to paint them again. This time, what should I do?
etch primer?
Any silicone on the parts in question? Or coating of any kind that panel wipe wouldnt get off?
Assuming nothign out the ordinary - etch primer or a blocking layer should get you a surface to spray onto.
Geoff
as said previously or you havent keyed the surface enough
Try a quick rup-up with a Scotchbrite pad, then etch-primer. Normal primer shouldn't have peeled off so there must be a reason. Was the metal too cold/damp?
quote:
Originally posted by owelly
Was the metal too cold/damp?
bloody good scrub/scour followed by etching primer.OR could be where you are painting. I have had probs in the past when i have gone in to my shed early morning when its abit wintery and fired up my compressor to spray a chassis for a a honda 500. it turns out that because i fired up a portable calor gas heater in the cold shed it caused humidity on the cold frame preventing proper bonding of paint. could you be doing something similar? even body heat can cause condenstion on chilly parts if you are in a confined space.
I've just re-read your original post....what did you use to degrease the metal?
most imporant thing for any paint/primer to stick to a surface is that it has a "rough" finish - by that I don't mean it has lumps
& bumps, but that the surface is "keyed" - you don't need an etch primer (tho' that will do the job for you as it creates its
own "rough surface" by eating into the metal) - providing the surface is degreased & "roughed up" with say 400/600 grit wet
& dry any paint or primer then has something to grip & stick to.
Wipe it down with cellulose thinners to clean it after you've rubbed it down with some 180 or 240 grit paper. Warm it up with a hot air gun or blow heater before you prime it again.
Id say the metal was too cold. Cold metal will have condensation on it.
Even if you key it it wnt stop the condensation, as said warm in up but not with a gas heater.
I'm thinking of getting an IR heater again...
Its ALL down to PREP... PREP and more PREP!!
Poor prep work give a poor finish. Thats what my mate says, and he is the Foreman / Head Sprayer at Marshalls Special Bodies Division, so he should
know his stuff with his 28 years experience.
Its the same reason why the powder costing is peeling off my chassis.
They didnt prep the chassis well enough.
It should have been shot / sand blasted to key up the surface, as well as degreased.
Same reason why Rusty Nuts is stripping his car this winter to re-paint the chassis.
Its an age old problem, and has been well discussed on here.
Sorry there is no easy way to say this!
:cool