Engine bay metal prep

I painted today. Painting outside (little bit of wind after my first coat), poor lighting, not dialing in the harbor freight gun as good as I should have, and first time using a HVLP gun...is a recipe for disaster but fortunately most if it won’t be seen much. Overall I think I’ll be happy with it. I’ll post pics soon.
I read someone lets the epoxy primer and activator sit overnight instead of the 30min induction time. Did I read that correctly? How long with the epoxy + activator last if I put them in a sealed container?
 
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What do you guys like to use to sand defects/overspray/runs before another coat? How long should I wait until sanding?
I can bondo or apply truck bed liner over epoxy primer within 7 days, correct?
 
I knew I read it somewhere. I should have consulted the manual again. Thanks!
Some of the paint seems pretty soft in areas I over sprayed so it may be tricky with sanding.

The firewall can move/pop in and out in the center with pressure from either side. With the help of a bodywork dolly if I pound a pea sized ding in the firewall could that get rid of the movement?
 
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jelco said:
I knew I read it somewhere. I should have consulted the manual again. Thanks!
Some of the paint seems pretty soft in areas I over sprayed so it may be tricky with sanding.

The firewall can move/pop in and out in the center with pressure from either side. With the help of a bodywork dolly if I pound a pea sized ding in the firewall could that get rid of the movement?
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If you have an opening nearby, like a heater box cutout etc... or an edge, try tapping the edge towards the oil can with a flat body hammer. May take a few tries, tap the edge a few times and check the oil canning, rinse and repeat.
 
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I applied bondo on the firewall to smooth it out and used it on some of the seams I sand blasted. First time using bondo. I hate the stuff. It’s dries too fast and I didn’t using much hardener (I know you’re supposed to use 2% i.e. 50:1). In hindsight it probably would have been better/easier to weld a piece of sheet metal over the entire firewall like I’ve seen others do.

The manual says “You have 7 days to apply 2k primer or body filler over epoxy without sanding [with 180 grit] first.”

What do you use, other than compressed air, to clean the bondo dust from the surface?

I imagine it’s better to recoat epoxy as soon as possible, after 3 days better than 6 days. If I were in Phoenix, AZ in the summer would I still have 7 days to spray another coat of epoxy?
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jelco said:
I applied bondo on the firewall to smooth it out and used it on some of the seams I sand blasted. First time using bondo. I hate the stuff. It’s dries too fast and I didn’t using much hardener (I know you’re supposed to use 2% i.e. 50:1). In hindsight it probably would have been better/easier to weld a piece of sheet metal over the entire firewall like I’ve seen others do.

The manual says “You have 7 days to apply 2k primer or body filler over epoxy without sanding [with 180 grit] first.”

What do you use, other than compressed air, to clean the bondo dust from the surface?

I imagine it’s better to recoat epoxy as soon as possible, after 3 days better than 6 days. If I were in Phoenix, AZ in the summer would I still have 7 days to spray another coat of epoxy?View attachment 14628
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Are you keeping in outside? The UV's will shorten that 7 day window a lot.. I think Barry told me a good day in the sun is equal to 5 days inside. I live down in Sonoita and do all my painting outside to so I get it :).
 
Yes, daringly painting outside.
Well, that makes sense to me. I called SPI and asked specifically about different temperatures and AZ heat but I may have been talking to a new guy, he said the 7 day window still applied but maybe I didn’t specifically ask about drying in the sun. The frame paint seemed to be quite hardened today but I mostly painted areas and parts today that were sanded with fine grit. I painted over some frame areas that looked like they were cured. I hope it has good adhesion.

I wiped the sanded bondo on the firewall with 710 solvent, sprayed it with air again, waited 30-45min then used a little left over activated epoxy paint. I noticed some spots were difficult to wipe down (friction on my cloth) but the spots that had good pint application were very smooth.
I ran out of paint in my gun so I didn’t finish the firewall. I imagine bondo needs a couple coats but the ripples won’t go away. It is just the firewall after all so I don’t mind much.
After doing all this, I wouldn’t recommend putting bondo on a dinged up and warped firewall but I wanted to experiment with it.

sorry for the long rambling
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Applying and blocking filler is an art. Skim the whole panel and then block with a long board with 80 grit then 180 grit. A block roughly 12-18” long is what I would use on that firewall. Use a guide coat so you can see the lows.

Use a quality filler that sands easily. I like Rage Ultra.

I’m sure there are a lot of YouTube videos.

Don
 
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dhutton01 said:
Applying and blocking filler is an art. Skim the whole panel and then block with a long board with 80 grit then 180 grit. A block roughly 12-18” long is what I would use on that firewall. Use a guide coat so you can see the lows.

Use a quality filler that sands easily. I like Rage Ultra.

I’m sure there are a lot of YouTube videos.

Don
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Agree, if you are truly using Bondo from AutoZone you are making way too much work for yourself. Like Don said get some quality filler.. It sands so much easier. 3M Platinum and Platinum Plus are 2 that I use. Oh and if you expected to apply one coat and have it flat get that idea out of your head... :) It may take 2 or 3 repeats of what you just did to really get it nice.
 
Yep, autozone bondo. I read you shouldn’t fill a spot than needs more than 1/4” otherwise the bondo will eventually crack. To make the firewall straight with no waves Im afraid I’d have to use a whole lot of bondo.
 
My Duster has more than a 1/4" to fix a problem in the LF fender. If you do what you are doing, epoxy, filler, seal with epoxy, filler, seal with epoxy I don't think you will have any issues. The pros here please correct me if I am wrong, thou many won't admit to how much filler they use after seeing the craftsmanship of some of the metal workers here like @MP&C they feel ashamed (like I do) :D
 
I find that once I commit to filler I intend to keep working to get it as good as my limited hill billy skills can. Something just sorta filled and painted looks worse to me than something dented and cleaned and painted. JMO What would be a better place to learn and practice than the firewall.
 
I should have taken a straight edge to it before applying bondo, practiced bodywork a little more and tried to hammer it straight. Maybe I can try to at least get the upper half better
 
If you still have the oil can problem you may have to use a short block and concentrate on just getting it smooth and not so much straight and flat.
 
This is what the firewall looks like now. I think I’m just going to leave it. With my skill level it’s going to take more time than I’m willing to spend and I want to get back to driving my car asap.

This whole process has certainly been a learning experience. Overall I think the paint looked pretty good after the initial day of painting with my harbor freight gun. I don’t have anywhere to paint other than outside and after leaving it outside for 2-3 days I tried to do touch up work on the chasis and other things I sandblasted. From my experience mechanical adhesion (after sanding with 180 grit) just isn’t as good as chemical adhesion (paint on bare sand blasted metal and uncured paint). After painting 2-3 coats on some sanded areas it still doesn’t look that good, the color is more grayish. Maybe I don’t know how to sand or paint. Lol.
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jelco said:
Yes, daringly painting outside.
Well, that makes sense to me. I called SPI and asked specifically about different temperatures and AZ heat but I may have been talking to a new guy, he said the 7 day window still applied but maybe I didn’t specifically ask about drying in the sun. The frame paint seemed to be quite hardened today but I mostly painted areas and parts today that were sanded with fine grit. I painted over some frame areas that looked like they were cured. I hope it has good adhesion.

I wiped the sanded bondo on the firewall with 710 solvent, sprayed it with air again, waited 30-45min then used a little left over activated epoxy paint. I noticed some spots were difficult to wipe down (friction on my cloth) but the spots that had good pint application were very smooth.
I ran out of paint in my gun so I didn’t finish the firewall. I imagine bondo needs a couple coats but the ripples won’t go away. It is just the firewall after all so I don’t mind much.
After doing all this, I wouldn’t recommend putting bondo on a dinged up and warped firewall but I wanted to experiment with it.

sorry for the long rambling
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I am sure you talked to Barry (owner)... did you mention just the heat and not sitting in the sun under UV? If not then call or text him again and ask specifically about drying in the direct sun.
 
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