Rust Removal

[sgo70]

I got my '30 Model A that I'm trying to prepare for paint. So far it's been a combination of a Zip wheel, Scotchbrite discs, and a cheap siphon feed sandblaster (shooting at about 100PSI so it's doing quite well).
I don't want to warp it or make it too thin so I'm using a Sill #1 sand. I noticed that on some parts there is a black coating that I think is the zinc oxide cause the paint is coming off pretty easily in comparison.
My question is do I have to completely get that off before I start with my fibre filler and Proform self etching primer. I also have Dominion sure seal primer/surfacer if that matters.
I'm trying to go for a good quality paint job but I don't want to wreck the sheetmetal in doing so.

Thanks a lot,
Sean

 

[sgo70]

Here's some pics:

Sean

 

[eyesore]

Sean,
I typically don't take it all the way to the bare metal but I'm sure there are plenty of paint guys around here that can give you better advice on how to proceed.

ISore

 

[chopshopcustoms]

I got my '30 Model A that I'm trying to prepare for paint. So far it's been a combination of a Zip wheel, Scotchbrite discs, and a cheap siphon feed sandblaster (shooting at about 100PSI so it's doing quite well).
I don't want to warp it or make it too thin so I'm using a Sill #1 sand. I noticed that on some parts there is a black coating that I think is the zinc oxide cause the paint is coming off pretty easily in comparison.
My question is do I have to completely get that off before I start with my fibre filler and Proform self etching primer. I also have Dominion sure seal primer/surfacer if that matters.
I'm trying to go for a good quality paint job but I don't want to wreck the sheetmetal in doing so.

Thanks a lot,
Sean

I d suggest bringing it to a sandblaster- and in one big swoop clean it all out. SOmetimes paying someone is worth your time and effort - you are worried about ruimning sheet metal that may already be too thin to really be 'right'.

 

[sgo70]

I was thinking about finding a trailor and loading it up. The sheetmetal is actually in good shape except for a couple of spots on the drivers side door that have pitted on the inside. I was thinking I should cut it out cuase its only two little sections about 2x2". You can see the pinholes in the picture.

Sean

 

[nowr]

get a mudhog

 

[35Mastr]

get a mudhog

Please tell us more about this MudHog??????????

The only one that I have ever seen is for drywall.

 

[rustbucket49]

Here is the advise I got from a professional auto painter using ppg products. It is VERY, VERY difficult to get all the rust off - even by blasting. Typically the professional blasters will use soda to blast the sheet metal and you can't get all the rust off no matter how hard you work at it. You and I use regular sand at the house since we use lower pressure blasters - less chance of warpage. So here are the steps they recommended (and what I've done - right or wrong....)

1. "Bulk" rust removal first as you're doing (either by blasting, sandpaper or the course rotary discs - whatever they're called... I've had the best luck on larger panels w/ the rotary discs on a power drill).

2. After that get the red scotchbrite pad and scrub down the panel using phosphoric acid. You can buy the stuff at Home Depot. Clean it off w/ paint thinner and repeat w/ the acid. You want to do this until you're not getting any "free rust" off the metal. At that point, wipe it down real clean w/ paint thinner. The rust that was remaining will be black from the phosphoric acid.

3. Apply your acid primer (like a ppg D8099) or a good epoxy primer like a DP50. Note that Step #2 w/ the phosphoric will buy you some time before you absolutely have to get primer on it. I have found that the D8099 is great for sealing the panels before going back w/ your high build, etc.....

If you take it to a shop, be prepared to fork over some major jack. I got lazy and took 2 doors (that had already been stripped once and reprimed!!) and a hood. To do EXACTLY the same steps described above (further evidence that this is the "preferred" way by professional shops) it cost me 1100 freaking dollars. I am still bouncing off the ceiling.....

Obviously, if you're doing a 1 footer paint job that is on a show car, this process may not be preferred - in which case you'd probably go the chemical strip. However, since this website is entitled "RAT Rods Rule", I presume this technique will get you in the ballpark for body prep. Hope this helps. I am pretty sure someone out there knows MUCH MORE about this than I do and I welcome any comments - I am still learning from past successes and failures.

 

[rustbucket49]

Has anyone ever tried electrolysis for rust removal? I have cleaned small pieces using the process - works pretty well if you have sufficient sacrificial material and current supply.

 

[chopshopcustoms]

Here is the advise I got from a professional auto painter using ppg products. It is VERY, VERY difficult to get all the rust off - even by blasting. Typically the professional blasters will use soda to blast the sheet metal and you can't get all the rust off no matter how hard you work at it. You and I use regular sand at the house since we use lower pressure blasters - less chance of warpage. So here are the steps they recommended (and what I've done - right or wrong....)

1. "Bulk" rust removal first as you're doing (either by blasting, sandpaper or the course rotary discs - whatever they're called... I've had the best luck on larger panels w/ the rotary discs on a power drill).

2. After that get the red scotchbrite pad and scrub down the panel using phosphoric acid. You can buy the stuff at Home Depot. Clean it off w/ paint thinner and repeat w/ the acid. You want to do this until you're not getting any "free rust" off the metal. At that point, wipe it down real clean w/ paint thinner. The rust that was remaining will be black from the phosphoric acid.

3. Apply your acid primer (like a ppg D8099) or a good epoxy primer like a DP50. Note that Step #2 w/ the phosphoric will buy you some time before you absolutely have to get primer on it. I have found that the D8099 is great for sealing the panels before going back w/ your high build, etc.....

If you take it to a shop, be prepared to fork over some major jack. I got lazy and took 2 doors (that had already been stripped once and reprimed!!) and a hood. To do EXACTLY the same steps described above (further evidence that this is the "preferred" way by professional shops) it cost me 1100 freaking dollars. I am still bouncing off the ceiling.....

Obviously, if you're doing a 1 footer paint job that is on a show car, this process may not be preferred - in which case you'd probably go the chemical strip. However, since this website is entitled "RAT Rods Rule", I presume this technique will get you in the ballpark for body prep. Hope this helps. I am pretty sure someone out there knows MUCH MORE about this than I do and I welcome any comments - I am still learning from past successes and failures.

LOL- so Im thinking maybe you are assuming some of us hee arent 'professional shops'..lol
Yes you are correct on much of the process, BUT most of it is not legal to do at your home (espcecially around her wiht acides and stuff)so I always suggest to leave it to a pro- we do this stuff for a living- so we can work with anything else that happens to pop up unexpectedly as well.

And as for being 'jacked ' on a proce- time materials and labor arent cheep for ANYTHING these days- when we the last time you paid your plumber $25 for fixing somehting? Welcome to 2008!

 

[Sam_Fear]

Has anyone ever tried electrolysis for rust removal? I have cleaned small pieces using the process - works pretty well if you have sufficient sacrificial material and current supply.

Yep - good stuff. There are a few good threads about it on here and Maddog has an article in Traditional Rod And Kulture.

Search 'electrolysis'.

 

[rustbucket49]

LOL- so Im thinking maybe you are assuming some of us hee arent 'professional shops'..lol
Yes you are correct on much of the process, BUT most of it is not legal to do at your home (espcecially around her wiht acides and stuff)so I always suggest to leave it to a pro- we do this stuff for a living- so we can work with anything else that happens to pop up unexpectedly as well.

And as for being 'jacked ' on a proce- time materials and labor arent cheep for ANYTHING these days- when we the last time you paid your plumber $25 for fixing somehting? Welcome to 2008!

Chopshop, I agree with your comments - I wish I could take my stuff to a shop, but I am just a major tight wad and figure I can do most stuff myself - actually the $1100 I paid was a fair price for what they did..... No doubt you guys would do a much better job than I can do and could get the "1 footer" that I can't get, but I am after a "30 footer" !! .....and to answer the last question, I have never paid a plumber ANY money to do ANYTHING - guess that's why my shower is still leaking.

 

[chopshopcustoms]

LOL... I have to day the only reason I pay my plumber is because he is good AND a car guy.