From wet sanding to color
- Thread starter old soul
- Start date
It depends a lot on the product and at what stage you sanded it.
Example, lets say you used a 2K primer, shot three coats and sanded it in 2 hours and if we knew the full cure time to be 20 days, then if you let it set to long and the primer cures out , yes adhesion can be compromised.
A lot of ifs, buts and where-withs in this statement and if you hit the worse part of the scenario, what would be the result you might get? In stead of 100% adhesion, maybe 60-70 %, is the paint going to fall off because of this? No but could be more stone chip prone.
What would the 222 do? A lot, keeps the economy going because you spent money, gives you something to do and it is one more layer of something to cause a problem down the road. Other then the mentioned, no good will come from using it in this case and lets be fair, the same would go for using my 600 in this case.
Example, lets say you used a 2K primer, shot three coats and sanded it in 2 hours and if we knew the full cure time to be 20 days, then if you let it set to long and the primer cures out , yes adhesion can be compromised.
A lot of ifs, buts and where-withs in this statement and if you hit the worse part of the scenario, what would be the result you might get? In stead of 100% adhesion, maybe 60-70 %, is the paint going to fall off because of this? No but could be more stone chip prone.
What would the 222 do? A lot, keeps the economy going because you spent money, gives you something to do and it is one more layer of something to cause a problem down the road. Other then the mentioned, no good will come from using it in this case and lets be fair, the same would go for using my 600 in this case.
Thanks for the reply, Barry. Most of my jobs sit for months before they are ready to be wet-sanded all over (restorations); surely the primer is fully cured by then and the worst case scenario would be avoided. I use SPI epoxy all through the bodywork and blocking steps and final prime with Turbo. Thanks for straightening me out on the 222...........you the MAN, Barry!!
B
Bob Hollinshead
OldSoul, I bet your work holds up well given the products and cure time. I've done some testing with Barry's adhesion promoter and found that it does help alot when basecoating over cured epoxy but still not quite the durability of using epoxy as a sealer before paint. I haven't done any testing with the adpro over cured urethane surfacers but I'd bet it helps.
B
Bob Hollinshead
No I haven't tried it over cured paint, only sanded/scuffed cured epoxy. I was hoping it reopened the epoxy enough to skip any sealer usage, it helped a lot and the chip and scratch tests showed less seperation at the color to epoxy level than the test with color over scuffed cured epoxy. Sealer before bc still offered the best durability.
I took three steel test panels and sanded them with 80 grit da
cleaned with waterborned
sprayed two wet coats of grey epoxy with one hour between coats
placed the panels outdoors in the sun for three weeks
sanded the panels with 600 wet followed by a grey scotchbrite rub
mixed some epoxy as a sealer- reduced 25% and applied one thin coat to panel 1 and allowed it to flash a few hours
sprayed adpro on panel 2
panel 3 was left as is
applied three coats of Global bc catalyzed with universal activator and allowed to flash a few hours
sprayed three coats of universal clear
set the panels outside in the sun for three weeks
1st test- scratch to bare metal showed seperation between epoxy and color on panel 3 with no sealer or adpro
scratch test panel 2 was better with only slight seperation between epoxy and color
scratch test panel 3 showed no seperation between color and epoxy
test2 I placed all three panels at 20 yards and wacked them with a 12 guage 7 1/2 shot light dove load
chipping shows no seperation on the sealed panel, very slight seperation of color from epoxy on the adpro panel, and definate seperation of color from epoxy on the panel with nothing- also the chip damage is larger on this panel.
I took three steel test panels and sanded them with 80 grit da
cleaned with waterborned
sprayed two wet coats of grey epoxy with one hour between coats
placed the panels outdoors in the sun for three weeks
sanded the panels with 600 wet followed by a grey scotchbrite rub
mixed some epoxy as a sealer- reduced 25% and applied one thin coat to panel 1 and allowed it to flash a few hours
sprayed adpro on panel 2
panel 3 was left as is
applied three coats of Global bc catalyzed with universal activator and allowed to flash a few hours
sprayed three coats of universal clear
set the panels outside in the sun for three weeks
1st test- scratch to bare metal showed seperation between epoxy and color on panel 3 with no sealer or adpro
scratch test panel 2 was better with only slight seperation between epoxy and color
scratch test panel 3 showed no seperation between color and epoxy
test2 I placed all three panels at 20 yards and wacked them with a 12 guage 7 1/2 shot light dove load
chipping shows no seperation on the sealed panel, very slight seperation of color from epoxy on the adpro panel, and definate seperation of color from epoxy on the panel with nothing- also the chip damage is larger on this panel.
N
Novablue71
Great test info Bob, thanks for sharing this adhesion,durability test with us. Joe
I love that test Bob!!! Also pretty close to what my testing shows, for the times given.
Now, yes, I am tight lipped on the adpro, as there is another company promoting it for everything out there under the sun and I do not want to get involved with those recommendations.
Here is one test we did and maybe why you will understand, why we want to use it for bumpers.
New ecoaded panel, recommended scuff and use an adpro (not us, saying that) adhesion for first 60 days 100%, 90 days 85%. six months 70%. This is why many production shops that use to do this, stopped.
Now all these times vary with temp and humidity and type of materials used.
Now, yes, I am tight lipped on the adpro, as there is another company promoting it for everything out there under the sun and I do not want to get involved with those recommendations.
Here is one test we did and maybe why you will understand, why we want to use it for bumpers.
New ecoaded panel, recommended scuff and use an adpro (not us, saying that) adhesion for first 60 days 100%, 90 days 85%. six months 70%. This is why many production shops that use to do this, stopped.
Now all these times vary with temp and humidity and type of materials used.
B
Bob Hollinshead
Interesting how over time the adhesion goes away with the adpro over ecoat testing, do you think that the overall shrinkage of the top coats over a long time period is stronger than the bond strength so that's what caused the adhesion to go downhill? People often don't understand that shrinkage not only affects the thickness of the coatings but also causes a linear tension and in extreme cases with actually warp a panel- filler on flimsy hood is an extreme example, the filler shrinks and pulls warpage into the hood around the perimeter of the application area.
Bob, you may be right.
I never really looked at problem but just know, I don't need to promote one product to use for everything that it is not needed for, just to sell product.
Over the years and one just in last month, I have gotten calls from production shops wanting to know why the front ends are coming back a year later all chipped up, all brands of paint inclued and SPI.
In EVERY case it comes down to, new panel and sprayed adhesion promoter before painting.
Had so many, now when I get the call, my first question is, new panel and did you use adhesion promoter. It keeps the phone calls short that way. Here is best part, don't matter if they used a gray pad, 180 - 600 first, still does it.
I never really looked at problem but just know, I don't need to promote one product to use for everything that it is not needed for, just to sell product.
Over the years and one just in last month, I have gotten calls from production shops wanting to know why the front ends are coming back a year later all chipped up, all brands of paint inclued and SPI.
In EVERY case it comes down to, new panel and sprayed adhesion promoter before painting.
Had so many, now when I get the call, my first question is, new panel and did you use adhesion promoter. It keeps the phone calls short that way. Here is best part, don't matter if they used a gray pad, 180 - 600 first, still does it.