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Old 02-26-2021, 10:33 PM   #1
ItWillBeSlow
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Stripping Paint From Cab - Need Surface Rust Tips

I have finished the rockers/cab corners/floor pans phase of my truck and am starting to prep the rest of the cab to get moving towards paint. My plan is to go bare metal and start with epoxy and go from there.

My truck has original paint + 1 respray + 1 coat of primer from 25 years ago, and I am beginning to sand through some areas to address dents, surface rust, and whatever else I don't know about yet. I am starting on the cab and am finding there is likely a fair amount of surface rust under my paint.

I have some major surface rust/pitting, that would require me to remove a fair amount of metal to get out completely. I have some "mild" surface rust that I can get shiny using red roloc surface prep pad with some effort. And I have some "very minor" surface rust that is fairly easy to remove with the roloc pad and low effort, about everywhere I have cut through.

Attached are a couple pictures for example.

Questions:
- Should I expect this "minor / mild rust" underneath all of my paint?
- What should I do about the "major" areas that require a heavy flap disc (or more) to get out? Is there another technique out there?
- While I can get a lot of this off, I am concerned my roloc discs will cut too many grooves/low spots in the metal that will all require filling. Am I overthinking this?

Open to all feedback and experiences here. I am doing this in a residential garage, and cant get it outside for blasting.
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Old 02-27-2021, 11:33 AM   #2
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Re: Stripping Paint From Cab - Need Surface Rust Tips

The best way to remove rust in the pitted areas is media blasting..you might try one of the small spot blasters if your trying to avoid a whole cab blast...there are some chemical strippers, but I havnt used any of them..if you've got rust under the paint then it for sure needs removed..
By the time you get the pitted area clean, apply the epoxy and high build primer, most of the pits will disappear,,those that dont can be filled with metal glaze or similar products..
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Old 02-28-2021, 06:46 PM   #3
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Thanks. I do have a spot blaster I could use to try the pitted areas. It is a pain inside the garage due to the mess it makes, but its feasible. I was using coal slag, and bought some garnet today to see of its any better

I took a 80 grit pad on my orbital sander to the roof today to see what was underneath. Similar small patches of surface rust, and another small pitted area. I do think I will try chemical stripper on some areas of the cab to try and speed this up.

The 80 grit pad still needed some elbow grease to take off the small surface "patches" in the photos, I expected it would take this rust off easier.

If there's anymore feedback on the amount of surface rust on the truck and best practices to remove, please share.

Pictures below from the roof area.
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Old 02-28-2021, 11:15 PM   #4
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Try using a "paint removal/stripper disc". They make them for an angle grinder as well as a drill. They look like a hardened sponge. They work pretty well for removing rust if its not so pitted. I bet it would work for some of the areas that you posted. For some of the deeper pits - I would use a wire wheel for a drill. Both methods will take awhile and both require proper PPE (face shield for sure). They can both be done in your garage for pretty cheap, just lots of labor.

A chemical way you could try would be "naval jelly". It works well, its just alot more messy I'd say. You would also have to make sure its all washed completely before applying any primers. That would require lots of water and scrubbing and then to make sure you get all the water off so it doesn't flash rust. Plus the mess of cleaning the floor and all that. Just another option for ya.

Good luck!
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Old 02-28-2021, 11:48 PM   #5
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Here's what I did on my 55. After the paints been removed either chemically, or with grinding discs or by blasting it. Next step to wipe down with a quality metal prep to dissolve the rust in the pores of the steel and in the pitting . This beats grinding off a lot of good metal. Next Step two coats of the MasterCoat slim silver permanent rust sealer surfacer.to help to Level up the pitting. Step 3 as soon as the second coat of silver dries apply two coats of urethane or epoxy surfacing primer. Block sand it and then you're color. This type of system will provide you with maximum corrosion resistance rather than a regular production paint job.
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Old 03-01-2021, 12:51 PM   #6
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Be careful with the strip disks on the roof panel. They put a lot of heat in the metal and you can warp the panel easily with them. You may want to try an ospho treatment on the pitted metal. If you do use ospho you need to make sure it is neutralized correctly before applying the primer.
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Old 03-01-2021, 01:15 PM   #7
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Re: Stripping Paint From Cab - Need Surface Rust Tips

I second the stripper discs. They work fast. I havent had any heat issues with them but watch for any material they leave behind on the metal. If I am stripping a large area I will use one of those discs and go back over it with a DA and 80 grit.

Ospho/naval jelly would work for the pits just make sure you do prep however the paint company you use says to after. Each paint is different and has different levels of acidity.
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Old 03-01-2021, 11:19 PM   #8
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Thanks for the feedback everyone. I ordered some stripper discs tonight and should have them by the end of the week. If I can get this job done without the chemical stripper, I will try to.
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Old 03-05-2021, 12:45 PM   #9
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Got some discs delivered yesterday. They definitely can do the job FAST. I almost wonder if they are to aggressive, I've removed some sample patches. I have to tilt the disc just a bit to concentrate the pressure, and it takes everything off very quick. I can't tell that it is removing metal but I am afraid it could make some micro-grooves, I might just need to practice a little more or I may be worrying unnecessarily..

I do think they add a lot of heat very quickly, and 1-2 seconds in any general area you need to keep moving, the panel heats up quick.
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Old 03-05-2021, 07:46 PM   #10
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Re: Stripping Paint From Cab - Need Surface Rust Tips

If you want to do it super fast, buy a SCT tool from Eastwood with the 40 grit drum. You can adjust the speed and it smokes the paint to bare metal very quick. I have one and it makes quick work on any task.

https://www.eastwood.com/eastwood-contour-sct.html

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Old 03-08-2021, 07:44 PM   #11
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Quote:
Originally Posted by 71meangreenc10 View Post
If you want to do it super fast, buy a SCT tool from Eastwood with the 40 grit drum. You can adjust the speed and it smokes the paint to bare metal very quick. I have one and it makes quick work on any task.

https://www.eastwood.com/eastwood-contour-sct.html

Smitty
I'm an old painter maybe I'm not quite up to speed with the latest technologies. 40 Grit really makes me nervous in the sense that would create sand swirl marks in the paint after it's painted. educate me a bit
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Old 03-12-2021, 09:18 PM   #12
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Quote:
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I'm an old painter maybe I'm not quite up to speed with the latest technologies. 40 Grit really makes me nervous in the sense that would create sand swirl marks in the paint after it's painted. educate me a bit
I've never owned or used one of those eastwood SCT tools, however the videos I have watched make it look super easy. I don't know what their drum is made from, but I don't think it is actually a sandpaper equivalent, and likely wouldn't leave the scratches like one would think. Just a guess!
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Old 03-13-2021, 10:46 AM   #13
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Re: Stripping Paint From Cab - Need Surface Rust Tips

I checked out the video and it was very interesting. Unfortunately sand swell marks always appear later after the car's been painted. I had a roof job where the roof had been sandblasted and warped. I let my buddy ,who's a bodyman for 50 years fix the roof. He used filler common 80 grit then epoxy, and a year later the entire roof was all scratches. if I were to use that tool with the 40 grit wheel I would definitely follow it up with 220/320 before priming. If it takes off paint that aggressively it has to be a bit on the Rough Side they did use the terminology 40 Grit
The one sure thing about bodywork is you always learn things the hard way
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Old 03-13-2021, 09:26 PM   #14
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Re: Stripping Paint From Cab - Need Surface Rust Tips

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I checked out the video and it was very interesting. Unfortunately sand swell marks always appear later after the car's been painted. I had a roof job where the roof had been sandblasted and warped. I let my buddy ,who's a bodyman for 50 years fix the roof. He used filler common 80 grit then epoxy, and a year later the entire roof was all scratches. if I were to use that tool with the 40 grit wheel I would definitely follow it up with 220/320 before priming. If it takes off paint that aggressively it has to be a bit on the Rough Side they did use the terminology 40 Grit
The one sure thing about bodywork is you always learn things the hard way
Scratches in metal is not the same as scratches in bondo! metal doesn’t shrinks like filler so if you bury bondo scratches with epoxy and 2k primers there going to come back and haunt you not so much with metal if you want to do it right always use slick-sand for your high build primer over epoxy slick-sand has zero shrinkage even over 40 grit scratches
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Old 03-14-2021, 08:29 AM   #15
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Re: Stripping Paint From Cab - Need Surface Rust Tips

I used the 3M disc to strip these two 67 cabs to bare metal after multiple repaints and they worked good , No warping . sprayed with 2k urethane primer after .
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Old 03-14-2021, 08:37 AM   #16
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Re: Stripping Paint From Cab - Need Surface Rust Tips

https://www.jalopyjournal.com/forum/...c838fe5adca540 Thank you for that info In 1988 I was testing some primers because I wanted the most powerful primer there was. I painted a grille shell of a 38 Packard just to try the paint out. I noticed where the metal was pitted on the second coat the pitting was disappearing. Back then a lot of us used lacquer primers and glazing putty like Nitro stain. I found this to be pretty exciting , my wife didn't. The reason you put another primer over zinc phosphate epoxy is because of the zinc in the coating causes pin holes. This is the explanation I got from the lab at CFI. Slick Sand & Feather fill a been around for years I never needed it. I introduced this product to the hobby under the banner Get Rid of the Pits .I am retired now ,not doing too much painting It's been 32 years I still have that piece.
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Old 03-14-2021, 08:41 AM   #17
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Those work great you can get them for the 4Ē grinder I use them all the time
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Old 03-16-2021, 08:07 PM   #18
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Re: Stripping Paint From Cab - Need Surface Rust Tips

The 3m paint pads work great as does the Eastwood sct it's my go to tool for stripping paint and rust . The stripping drum is just like the 3m but much larger and works very fast. No heat build up to speak of . Epoxy followed with 2k high build primer never have any scratches come up in the paint
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Old 03-18-2021, 08:26 PM   #19
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Thank you everyone for the continued input and comments.

I used the stripper discs to get the cab pretty bare. Followed with an 80 grit sanding pad to remove any surface rust I didnt want to "dig at" with the stripper disc.

My next focus area is removing the light surface rust that didn't come off with the previous methods. I have a fair amount on the roof and back panel of the cab. Today I tested Eastwoods Metal Prep on a patch of the roof to see how much of this rust it would dissolve. Overall it looks pretty goodbut I have some questions about the minor rust that is in the tiny pits.

Here are the before and after of the test area:
Top pic: overall roof, as good as it was going to get without getting to aggressive with stripper disc
Middle Pic: test area with 30 minutes of metal prep and scotch bright
bottom pic: tape line of treated and untreated areas
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Old 03-18-2021, 08:31 PM   #20
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Close up mic of the "micro pitted" areas. I used a lens to get close-up of these spots.

Do these areas need to be treated further? Or will the metal prep + epoxy coat sufficiently neutralize and seal this rust in? I am concerned that something will bubble through the paint some day if I don't do this correctly.
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Old 03-18-2021, 10:55 PM   #21
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Re: Stripping Paint From Cab - Need Surface Rust Tips

The primary purpose of a primer is to prevent rust and corrosion. Epoxy primer 3 coats does seven, eight hundred hours of salt fog testing before it begins to deteriorate. It seals off the moisture but not the oxygen, that's why it begins to rust. Aluminum Pigmented moisture cured permanent rust sealer does 8000 of salt fog testing. This is the only type of primer that cuts off both the moisture and the oxygen. apply two coats and then a surfacing type primer either urethane or an epoxy. This will level up any pitting and should last several years. Will this truck be garage kept or parked outside ?

Last edited by lupo; 03-19-2021 at 08:53 AM.
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Old 03-20-2021, 09:34 PM   #22
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Re: Stripping Paint From Cab - Need Surface Rust Tips

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The primary purpose of a primer is to prevent rust and corrosion. Epoxy primer 3 coats does seven, eight hundred hours of salt fog testing before it begins to deteriorate. It seals off the moisture but not the oxygen, that's why it begins to rust. Aluminum Pigmented moisture cured permanent rust sealer does 8000 of salt fog testing. This is the only type of primer that cuts off both the moisture and the oxygen. apply two coats and then a surfacing type primer either urethane or an epoxy. This will level up any pitting and should last several years. Will this truck be garage kept or parked outside ?
What brand or specific product do you recommend for the sealer under the epoxy?

This will be a garage kept and fair weather truck for the rest of its days.
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Old 03-20-2021, 10:57 PM   #23
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Re: Stripping Paint From Cab - Need Surface Rust Tips

I used the Mastercoat Slim version to spray my panels. Dump it from the can into a primer gun and apply 2/3 coats. Recoat time2/3 hours
When the last coat is dry to the touch apply the epoxy or urethane surface or over it. Read the product data sheet and put on a pair of gloves before you open the can. If you need technical help Tech line is is on the can
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Old 03-21-2021, 01:54 AM   #24
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Sorry if my opinion is different than many, but w/o some blasting or letting a rust remover sit wet on the pits for some hours, then light blasting or scrubbing, you'll see paint failure.
People think rust remover, converter, whatever applied and turning the surface black removes rust. Wrong.
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Old 03-21-2021, 08:03 AM   #25
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Re: Stripping Paint From Cab - Need Surface Rust Tips

Donít panic but you can remove the rust from the pits by washing it down with Maratteck acid donít neutralize it with baking soda as that will affect the Epoxy primer just flush it with water and dry with a towel to prevent flash rust
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