Filling rough metal caused by rust

DougT

Promoted Users
Hi everyone! This my first post on any auto forum. Over the past few months I have been reading many posts on this SPI forum, and from a novice, consider it the best. I am starting to work on my first car that I had in high school 51 years ago. It is a 1954 Chevy 210 post. I have been trying to learn all I can about removing rust and using SPI epoxy primer. The whole phosphoric acid debate is still confusing to me. I am sure I will have many questions in the future, but for this post, my question is: On pitted areas that are caused by rust , no pin holes and mostly solid, what is the process to fill and smooth the area? My thought is to sand blast the area, wash with a phosphoric acid, neutralize well with water, use W&G remover, spray with SPI epoxy, a day later use some king of glazing putty over primer and the rough metal area (RECOMMENDATIONS GLADLY ACCEPTED FOR BEST PRODUCT), sand, W&G, and coat again with epoxy. If more that 3 or 4 days, use a maroon pad to scuff surrounding primer before priming. Does this sound like a GOOD plan? Better ideas? Any need to sand primer before using glazing putty? Thanks!
 

Jim C

Oldtimer
your almost good but making it harder on yourself. if your blasting, which is the best approach to rust, you dont need any acid. simply blast, spray 710 on the blasted area until its dripping, blow it off with air then apply epoxy. dont touch a blasted surface with a rag or your going to end up with a massive amount of fuzz. your basically blasting, giving a rinse with 710 then epoxy it.
 

texasking

Promoted Users
As Jim said above, no need for acid when blasting. Any filler that requires hardener will work to fill pits. My favorite is Rage Ultra and the dolphin glaze works well for small scratches or pits. Epoxy does not need to be sanded for 7 days inside to apply filler. After 7 days, scuff lightly with 180 and maroon scotchbrite up to 30 days. After 30 days, it must be sanded with 180 and epoxy reapplied.
 

sprint_9

Rookie
If it were mine Id be inclined to keep using epoxy until you are done with the pits. 3-4 coats of epoxy with an hour or more between coats, wait a day or two, block, then repeat till you are flat. Another option, or on any deeper pits, would be to dab epoxy into the pits with small brush and sand flat.

That being said this certainly isn't the cheapest, quickest, or easiest route to finishing it.
 

DougT

Promoted Users
As Jim said above, no need for acid when blasting. Any filler that requires hardener will work to fill pits. My favorite is Rage Ultra and the dolphin glaze works well for small scratches or pits. Epoxy does not need to be sanded for 7 days inside to apply filler. After 7 days, scuff lightly with 180 and maroon scotchbrite up to 30 days. After 30 days, it must be sanded with 180 and epoxy reapplied.
Thanks! Would the glaze be better? Thinner for just a very thin coat? 40 years ago I used some kind of glaze that I think was a lacquer base in like a toothpast tube. Dried fast and sanded smooth. Is lacquer a nono?
 

DougT

Promoted Users
your almost good but making it harder on yourself. if your blasting, which is the best approach to rust, you dont need any acid. simply blast, spray 710 on the blasted area until its dripping, blow it off with air then apply epoxy. dont touch a blasted surface with a rag or your going to end up with a massive amount of fuzz. your basically blasting, giving a rinse with 710 then epoxy it.
Thanks Jim! That will save me some time. Do you have a favorite filler for thin, rough surface filling?
 

Jim C

Oldtimer
lacquer putty is a no no. the previously mentioned upol dolphin glaze is great stuff. if you need something thicker though for deeper fills then i always use evercoat quantum but to be honest i dont use much filler anymore other than the dolphin glaze. i really dont know what is out there these days that is good. the quantum is really good stuff though. some type of epoxy polyester hybrid. sands easy too.
 

theastronaut

Promoted Users
After blasting, let it sit a few days to see if any rust pops back out. Use a really fine abrasive, course abrasive won't get deep enough into the pits to remove all the rust. It's really easy to miss small specs in deeper pits; letting it sit a few days (especially if its humid) will help highlight any areas that need blasting again to fully remove rust.

This is a week or so after I blasted this firewall. It looked 100% clean right after blasting, but these areas popped back up from deeper pits that hadn't been cleaned out well enough.

uVWJUF3h.jpg
 
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DougT

Promoted Users
lacquer putty is a no no. the previously mentioned upol dolphin glaze is great stuff. if you need something thicker though for deeper fills then i always use evercoat quantum but to be honest i dont use much filler anymore other than the dolphin glaze. i really dont know what is out there these days that is good. the quantum is really good stuff though. some type of epoxy polyester hybrid. sands easy too.
Thanks Jim! SPI recommends using the 700-1 waterborne WGR. Your thoughts?
 

Chris_Hamilton

Trying to be the best me, I can be
Thanks Jim! SPI recommends using the 700-1 waterborne WGR. Your thoughts?
If you are doing it like Jim stated then you want to use 710 being it's a solvent. 700 for sanded metal Honestly though many of us go straight to epoxy after blasting without using anything. Properly blasted metal is clean enough that you don't really need to use anything. Trying to wipe something blasted down will make a mess with lots of fuzzies from the wipes. Also solvent based W&G remover works by lifting contaminants then they are wiped off. Spraying it on and doing nothing (wiping) doesn't really accomplish anything.
 

DougT

Promoted Users
After blasting, let it sit a few days to see if any rust pops back out. Use a really fine abrasive, course abrasive won't get deep enough into the pits to remove all the rust. It's really easy to miss small specs in deeper pits; letting it sit a few days (especially if its humid) will help highlight any areas that need blasting again to fully remove rust.

This is a week or so after I blasted this firewall. It looked 100% clean right after blasting, but these areas popped back up from deeper pits that hadn't been cleaned out well enough.

uVWJUF3h.jpg
Good advice!

That is why in my original post I had a step to use phosphoric acid of some brand prior to priming. It just seems like some kind of liquid rust remover would get into the areas you cannot see. But I totally understand reasoning of why not to use it. What is your opinion on it?
 

Jim C

Oldtimer
Yeah chris i wanted to say that i typically blast, blow off with air and go straight to epoxy but i also know my media and that its clean with nothing in it. If he knows the part is perfectly clean before blasting and the media is clean then just go for it and skip the 710. Otherwise i usually soak the part with 710 until its dripping on the floor then blow off all the excess to give it basically a rinse and blow dry.
 

theastronaut

Promoted Users
Good advice!

That is why in my original post I had a step to use phosphoric acid of some brand prior to priming. It just seems like some kind of liquid rust remover would get into the areas you cannot see. But I totally understand reasoning of why not to use it. What is your opinion on it?

I've used Ospho after DA sanding to bare metal on large open panels like door skins or bed sides that would easily warp by blasting the panel. The F100 project I'm currently working on had been stripped to bare metal and shot with lacquer primer, which didn't seal the metal and now it has small rust pimples all over the outer sheetmetal. Spot blasting would stretch each spot and make the panels lumpy so that wasn't an option. I masked out the panel to keep the acid contained and applied Ospho with a scuff pad, and the spots were hit with a wire brush occasionally to work the acid in better. The acid needs to stay wet the entire time, and it has to be thoroughly rinsed with water afterward. Any flash rusting from rinsing can be cleaned up easily with a wire drill and DA sander.

The process used really just depends on if it matters if that panel can be stretched by blasting or not. Blasting aggresively enough to remove this kind of rust will stretch/warp the panel, so I only like to blast inner door frames, door jambs, firewalls, etc that don't have to be bodyworked laser straight like the outer panels.

Robert (MP&C) has a really good post on sandblast warping and how to avoid it here-

GlP5M73h.jpg



After soaking and scrubbing, 95% cleared up. It takes a while to get the really deep pits cleared up.

ZOQ4EG3h.jpg
 

DougT

Promoted Users
If you are doing it like Jim stated then you want to use 710 being it's a solvent. 700 for sanded metal Honestly though many of us go straight to epoxy after blasting without using anything. Properly blasted metal is clean enough that you don't really need to use anything. Trying to wipe something blasted down will make a mess with lots of fuzzies from the wipes. Also solvent based W&G remover works by lifting contaminants then they are wiped off. Spraying it on and doing nothing (wiping) doesn't really accomplish anything.
Thanks Chris, and all who have posted advice to this thread. Hear directly from those that do this type of work is really a great service to us just starting a car project.

I have another rust question. I am not sure if I should post it in another thread or if I can continue here. I will ask it, and if I should do this differently, please correct me.

After I took off a piece of rear side trim, I found rust much worse than it looked creeping under the edges of the trim. After sanding and wire brushing and pushing hard with an ice pick, I found some rust through. I don't know the best path to take now. Should I cut it out and patch ( I have not done this before) OR sand blast and just weld up the holes? I feel like there is enough thickness around the holes, that I could do that. Behind the repair area has original undercoating. Does the undercoating have to be removed in order to weld?
Side rust.jpg
Side rust 2.jpg
It is in a tough area to get to. Hopefully the pictures will help explain my situation.
 

theastronaut

Promoted Users
Spot blast it and see how bad it is. If the holes don't open up or the pits aren't really thin then you could tack weld each hole up. Using a piece of copper behind the holes will help if from blowing through. Removing the undercoating is ideal if there is access.
 

DougT

Promoted Users
Spot blast it and see how bad it is. If the holes don't open up or the pits aren't really thin then you could tack weld each hole up. Using a piece of copper behind the holes will help if from blowing through. Removing the undercoating is ideal if there is access.
Thanks ! That was what I was hoping to do. I think I have access behind most areas, so will clean up behind weld.

I posted another post on "Metalwork" with the same and more pictures and questions. If you have time, and care to comment, I would look forward to your thoughts.
 
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