I just roller primed a board then painted it a medium green with 5% hardener in it to keep it from chalking after a year or so. The problem is it got a little rain on it an blemished. So next day I lightly sanded, then another coat of paint with 5% hardener in it. Big mistake! I had chemical reaction all over. It seems to be worse where I sanded. Anyone else have any thoughts? John Arnott
Posted by Joey Madden (Member # 1192) on :
I would think that sanding the board then using Rapid-Prep again would solve your problem, but then again, I never leave projects in the rain to dry!
Posted by Michael Boone (Member # 308) on :
I do double coats with catylized One shot on a fleet of trucks.I never had a problem. I do exactly the same as you did. I scuff with scotchbrite pads. I use 10% hardener. Did you use the One Shot brand name hardener? I wonder if the problem goes back to the primer? Please describe "chemical reaction"?
Posted by Joe Rees (Member # 211) on :
John, Sanding opened up the surface, exposing a less cured layer. If you had let it dry again overnight after sanding, or put less hardener (or less thinner) in the second coat, you would have probably been ok.
I hate it when that happens.
Posted by roger bailey (Member # 556) on :
John, my opinion; More then 5%hardner would probably have kept it from reacting, would have dried(cured from within) faster and harder.
Just my opinion.
Roger
Posted by Ryan E Young (Member # 2325) on :
Joes right on target.
Posted by Stephen Deveau (Member # 1305) on :
As as Joe and Joey said.
Yours surface was soft, In the cold rain it sat! No time to dry or the heat to cure it!
You sanded wet uncured paint and added more over the top. Both layers were trying to react to different curing times and 'WORKING AGAINS EACH OTHER"
Sit back and have a coffee until the first surface is dried enough to prep for the second one....
One shot Hardener is a great additive but still works different in all the Colours.
Black it's Fast Yellow it's Slow. Reds & Blues you watch as you go!
Posted by John Arnott (Member # 215) on :
First of all, it never rains here in southern California. Opps. . .oh yeh. . .the roof leaks right there. Second it only wreankled where it was "cut" by sand paper. Third, it seems to me that when I use 10% "chromatic" hardener it seems to flatten the gloss! I normaly don't thin the paint if its fresh.
Posted by Joey Madden (Member # 1192) on :
John I just don't get what you say since catalyst is also a gloss enhancer as well as a hardener. I have been using catalysts in my paints for many years. Even though you may think that 1-Shots hardener is a new thing for sign enamels, Chromatic came out with it in the early 90's. At 5% you are not really adding to faster dry time. I believe the starting point is 10% and can honestly say that I use quite abit more during my usage. I however let it sit for at least ten minutes after mixing it in the paint to let the bubbles disappear. Haven't had a problem with gloss or drying time for that matter.
I always prep my surfaces with Rapid-Prep even after sanding as using automotive type stuff usually leaves an oily surface, or at least thats what my hands told me in the past.
