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Roll/Brush on epoxy primer

#1
I had some questions regarding epoxy primer. I'm cleaning the floorboards/undercarriage on my 86 Mustang GT. There are some places that are good, yet some have some surface rust. For the epoxy primer, do I need to clean it all to bare metal? Does it matter if there are some spots that have some traces of paint? (the rust will be gone) If its best that its bare - I'll do it. I wanted to bush/roll it on. I read in some older posts that it can roll out decent. Reduce 1:1 to roll/brush? I know.. lots of questions - new to the product. Thanks!
 
#2
Your best results will be clean bare metal that's been sanded or sandblasted (best). Any old paint will need to be sanded or scuffed for texture/tooth.
Mix it 1:1, give it some induction time, and brush or roll it on. Save your leftovers for the next day. It takes longer to cure when applied this way so give it plenty of time before the next coat goes on-hours or overnight. I've brushed repair areas many times but never tried to roll it, the better the brush quality the better the coat will be.

do I need to clean it all to bare metal? SPI epoxy is some tough stuff once fully cured, it provides really good corrosion protection and some say even if some of the pits still have traces of rust in them they won't grow under the epoxy but your best chances for long term success is to remove all of the corrosion completely. If you have a compressor available investing in a blaster even if it's just a hand held spot blaster-will help make your cleanup a lot easier.
 
#3
Barry told me to brush or roll - do not reduce.
As always, he was right. It is plenty thin mixed 1:1.
Only problem I have encountered when brushing it is tiny air bubbles. Haven't figured out what I am doing to cause them.
 
#4
Thanks for the advice - I have to wait for a little warmer weather here.. didn't get out of the twenties today. I have a heater in the garage but it doesnt get warm enough for paint. I've got plenty of cleaning to do!! I've been watching Rusty doing those Mustang projects - amazing work! Great motivation..
 
#5
Im looking to do the rear part of my 70 camaro, Ive been reading about all kinds of products, however, Im considering throwing epoxy over whole bottom side. whats advantages of rolling on versus spraying on? seems like it would be thicker if you rolled, but better coverage with spray?
 

jlcustomz

evil painter
#7
Only real advantage of rolling is not having to deal with normal spraying issues such as overspray, fogging the air, gun cleaning etc.. Rolling won't give as consistent of a coating, coming out thicker in recesses & thinner on ridges & other high spots. Thicker areas will take much longer to cure.
However, for an underneath area where perfection isn't needed,rolling or brushing may be the better personal choice. For spraying underneath in a tight spot, a sprayer with a pressurized pot & hose to gun would probably be ideal.
 
#9
Barry told me to brush or roll - do not reduce.
As always, he was right. It is plenty thin mixed 1:1.
Only problem I have encountered when brushing it is tiny air bubbles. Haven't figured out what I am doing to cause them.
The tendency I have when brushing on epoxy is to apply it too thick. Works better to apply multiple thin coats so brush it out thin and the bubbles shouldn't be a problem.

Never cared for rolling it on. Just too much of a struggle to get it looking right besides, if I can get a roller on it there should be enough room to spray it.
 
#10
Bare in mind, when you brush or roll the epoxy, the flash time is really long. Since you have the 7 day recoat window, it is good to give several hours between coats. Also, since the pot life is 72 hours, it works well if you put a coat on in the morning, another late day, and continue for 2-3 days. I treated the welds on the bottom of my floors on the '53 this way and found that I had enough build to eliminate any rust pits after hand sanding with 180 or da-ing with 80. All without the mess of spraying and gun cleaning.

When I epoxied my welds, I brushed about a 1” strip first. Second coat went on about 2”, third 3” etc up to I think 4”. I never did use any filler. While it did not eliminate the welds, it "softened" them to the point, they were very acceptable.

This image is of the hand made floor pans with nothing but SPI red epoxy. seams brushed, sanded, and two coats sprayed. No filler.

John

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