How to remove paint/surface rust from farm vehicles?

[Itsjustdirt]

I have a few small farm trucks that have flaking, sun beaten, partially surface rusted paint jobs. I think sanding by hand will take too long and still won’t take care of deep “surface” rust spots. Is there a harbor freight media blaster that would work for this? I have a large compressor if that matters at all.

 

[NUTTSGT]

Check locally for somebody that will come to your place and blast them for you. You may find it'll be well worth the time savings and they "shouldn't" damage any panels.

 

[sberry]

Old equipment may not need blasting. It doesn't have to be perfect and some primers seal well enough over some rust if it is smooth. Get a DA sander, some 80 grit, a roll of 150 and maybe 220 and a box of purple scuff pads, the painters secret weapon.

 

[Hot Rod Grampa]

Might depend on what your final vision is. Total restoration or just keep it from getting worse. Sandblasting can warp sheetmetal quickly if done wrong so as with any tool there is a learning curve. I have used the small spot blasters, they look like a spray gun but with a ceramic tip. Only good for small spots before needing more media. But they work. Using a da is a good option but for deeper pits the spot blaster does a nice job without taking away too much metal. Good luck..

 

[6768rogues]

You could use a soda blaster. Soda will not warp panels like sand but it costs more. Sodium bicarbonate is available in 50 lb. bags. Then you might have to sand or use a Scotchbrite pad because soda can leave too smooth a surface for paint.

 

[TractorJeff]

Hot thing now is to just clear coat the weather beaten finish.

 

[1slow62]

electric grinder with a sanding disc is the easiest and cheapest. Spray some ospho on it after and primer/paint.

 

[ssffnomad]

Clear Coat over weather beaten finish = YUCK

 

[Jazz1]

I use a HF sandblasted. Runs off my 18 CFM @90psi compressor. Never warped a panel on any vehicle I’ve sandblasted. Only running 120 psi. I blast in portable shelter with poly on floor so I can recover media. Did complete 48 sedan delivery with 6 bags

 

[Itsjustdirt]

Interesting! What media did you use? Just for example, how long would it take to blast a door or tale gate? Any faster than grinding with a flap?

 

[dbabicky]

You could use a soda blaster. Soda will not warp panels like sand but it costs more. Sodium bicarbonate is available in 50 lb. bags. Then you might have to sand or use a Scotchbrite pad because soda can leave too smooth a surface for paint.

This right here. I have the SO soda blast gun and I buy the baking soda at my local farm Co-op for like $8.00 for a 50# bag.

 

[Jazz1]

Interesting! What media did you use? Just for example, how long would it take to blast a door or tale gate? Any faster than grinding with a flap?

I'm using Fine grit sand. I can sweep it up and reuse a few times. Much faster than flap disk to do door or tailgate. Rear door waS maybe 20 minutes and you clean paint and rust from all the areas disks can’t access like drip rails , seams etc

 

[rpcraft]

You can use a phosphoric acid mixture like the metal etch/prep they sell at home depot and time to remove rust fairly easy and with a lot less of an endeavor. It's about 16 bucks a gallon when i bought some on Saturday. Just don't do it over concrete or it will leave "cleaned" spots/ I set mine up on some plywood on sawhorses and just used some safety glasses and nitrile gloves , then just poured it on my inner fenders and spread it with a paint brush. After that I got some of the red scotch brite and dipped it into the etch material and scoured the metal pieces, then brushed on some more of the mix and then let it sit overnight. Most of the cleaner surface rust just came off and there was clean metal underneath, while the heavy rusted area's turn black. After that I rinsed it down again and give it a wipe down with more of the prep liquid and it will leave it so you can come back and paint it a little later without having to worry about flash rust right away. I spread it out in the floorboard of my project Jimmy as well on Sunday, and when I get home tomorrow I'm going to give it a rinse down and then do one more round. Once I do a final rinse down I am going to hit it with a coat of the rustoleum black rust reformer and then I just have a couple of small area's I need to weld in some patch pieces. Once I do that I'll hit those area's with some etching primer and coat the inside with some raptor liner.

 

[Itsjustdirt]

I'm using Fine grit sand. I can sweep it up and reuse a few times. Much faster than flap disk to do door or tailgate. Rear door waS maybe 20 minutes and you clean paint and rust from all the areas disks can’t access like drip rails , seams etc

Awesome! Is this one too small?


https://m.harborfreight.com/40-lbs-portable-soda-blaster-60801.html?utm_referrer=direct/not provided

 

[Jazz1]

Awesome! Is this one too small?


https://m.harborfreight.com/40-lbs-portable-soda-blaster-60801.html?utm_referrer=direct/not provided

That's plenty big enough, about the size of mine. You must sift your sand through porch screen. Do that and you won't find yourself constantly unclogging the valves. I have screened the sand and found as many as 2 dozen pieces the size of a corn kernel that will clog. I gave the same advice to fellow at my house yesterday who says his blaster constantly clogs.."SCREEN THE SAND"

 

[Retlaw 66]

If you use sand for blasting, you need to avoid breathing the dust. Silica dust can cause a lung disease, Silicosis. A supplied air respirator is best since a standard filter respirator will clog easily.
I've been having a difficult time purchasing blasting sand due to the crackdown by OSHA and the EPA. Commercial blasters have been affected too.... they now need to control the dust clouds they produce.

There is other blast media available which does not contain much silica. Some are on the expensive side, such as Aluminum oxide, but lower cost options such as crushed glass are more economical. There is another product called Jet Blast which I will try next. Costs just a bit more than sand and can be reused a few times.
https://www.escablast.com/blast-media/jet-mag/

The downside to soda blasting is the cost of the soda, and it can only be used once. You'll go thru a lot of it.

There are several options to chemically remove rust. The old Navel Jelly is a phosphoric acid gel, and Concrete etch and stain remover is also phosphoric acid. Muriatic acid (hydrochloric) is more aggressive but the cleaned surface will need to be neutralized. You can place a towel on the rust and soak it with the acid of your choice to keep it wet.

Lots of options to remove the paint. A simple razor blade scraper might work, or use a chemical stripper to soften the paint, then scrape. Might take a few applications depending on type f paint.... lacquer just 'melts', while enamel will wrinkle and practically fall off. Use a DA sander with 80 grit to get down to clean metal before priming.

I do like sandblasting, but it will warp flat, thinner panels used since the 60's. A pressure blaster will be much faster. A large fill opening is preferred since you will use a lot of media.

You linked to a HF soda blaster, here's the HF abrasive (sand) blaster:
https://www.harborfreight.com/110-lbs-pressurized-abrasive-blaster-60696.html

I would recommend chemical strippers and/or sanding to remove the paint, and limit blasting for the rusty areas or use an acid to remove rust.

 

[Retlaw 66]

Old equipment may not need blasting. It doesn't have to be perfect and some primers seal well enough over some rust if it is smooth. Get a DA sander, some 80 grit, a roll of 150 and maybe 220 and a box of purple scuff pads, the painters secret weapon.

Likely good enough for farm equipment. But also treat the rust with either a conversion coating (Loctite, Permatex, etc) or phosphoric acid to neutralize the rust.

If the paint surface is sound, just scuff and paint. If it's peeling of flaking, it will have to be removed if you want it to last.

Do you have some pics of the trucks?

 

[6768rogues]

I use a HF sandblasted. Runs off my 18 CFM @90psi compressor. Never warped a panel on any vehicle I’ve sandblasted. Only running 120 psi. I blast in portable shelter with poly on floor so I can recover media. Did complete 48 sedan delivery with 6 bags

I blasted a Rambler hood and ruined it. I had another hood so I turned down the air pressure to 100# and stood further back. It ruined the hood. I had a third hood, so I sanded it with sandpaper.

 

[Jazz1]

I blasted a Rambler hood and ruined it. I had another hood so I turned down the air pressure to 100# and stood further back. It ruined the hood. I had a third hood, so I sanded it with sandpaper.

These HF blasters use a small nozzle. That could be the difference. I am well aware of folks getting panels warped. Fellow was here yesterday. He dropped his '56 Merc for sandblasting at a business and they warped the rear of cab which is why i think too big nozzle or too much pressure. I'm just a hobbiest.
I also sandblasted completely my '41 truck without any issues. Hood and fenders were heavily pitted.

 

[Itsjustdirt]

I blasted a Rambler hood and ruined it. I had another hood so I turned down the air pressure to 100# and stood further back. It ruined the hood. I had a third hood, so I sanded it with sandpaper.

hahaha. oh man, so funny to read but I'm sure it wasn't funny at the time.

How did it ruin it?

 

[metlmunchr]

Every major automotive paint manufacturer has a disclaimer in their product info that says if you use soda and the paint fails, don't call them because you've been told up front not to use it if you plan to use their paint.

 

[sberry]

A main thing, I never use chemical stuff after but after blasting siy use pure pads and scuff a couple passes. It knocks the hi spots blasting leaves and loosens sand that blpes off. Blast, scuff, blow, paint.
I used to do all that stuff when I first started, metal prep stuff and do not anymore. I sand all I can, blast when I have to. Scuff as much as I can and am fussy about cleaning before I start.
I normally use industrial purple strong, hor hi pressure wash and then sand.

 

[sberry]

There are a lot of reasons paint fails especially after blasting. Some epoxy primers are rated to go over tightly adhered rust. All that zinc, self etch isnt any good over sandblast that hasnt been scuffed or sanded after. Blast leaves peaks, feel the difference, bare blast or blast scuff. The primer fills pits but the peaks poke thru, this is what rusts again, its not from the pits.

 

[Stevewr54]

Every major automotive paint manufacturer has a disclaimer in their product info that says if you use soda and the paint fails, don't call them because you've been told up front not to use it if you plan to use their paint.

Listen to this poster. Besides the paint issues soda gets everywhere and
will be hard to remove. When you add some moisture it corrodes like crazy.
Hope this helps, Steve

 

[myredracer]

duplicate.

 

[myredracer]

Soda for media blasting is a poor choice and is over-hyped. Metal preps with phosphoric acid in them are generally frowned up by car restorers but some claim good success. Not all metal preps are created equally. Ospho is a good one. Needs to be properly neutralized and washed before applying primer & paint.

The HF pot blaster works fine. They have a kit available for using media like coal slag & sand. I just used Black Diamond coal slag for stripping a car body. It's a good choice for sheet metal and comes in several grits. It's available from TSC for something like $10 a bag or so. The downside to the HF pot blaster is that you have to keep sweeping up the media and screen it and put it back in the blaster. Depending on how well you contain the media in some sort of enclosure, you can lose media into the surrounding area and may need to have some extra bags of media on hand. The coal slag doesn't create hazardous dust like silica sand. If you have much blasting to do, I'd get HF's largest blaster. I have the 40 pounder and it doesn't last long before emptying the contents. Blasting can be a messy and time-consuming process and after it's blasted, you need to get primer or paint on it quickly before it flash rusts.

If you blast, grind, sand or strip (such as by strip discs or chemical) to bare clean metal, epoxy primer is a very good choice and provides excellent corrosion protection. However, depending on the brand of primer, epoxy has a window of around 2-7 days before you apply paint in order to get a chemical bond between coats otherwise you'll need to scuff or sand the epoxy to get a mechanical bond which is a lot more additional work.

Another approach would be to simply use some rust converter paint. I really like Rustoleum's professional line of paint. Just need to remove loose paint & rust and clean the metal and then paint away. Much faster and will look great if done right. If it's agricultural equipment, it only needs to be "agricultural grade" anyway...

 

[Retlaw 66]

^^^ I agree with the above!

Soda blasting.... just do some research. It will leave a film on the surface that may affect paint adhesion. After blasting, the surface should be washed with water, and maybe a water/vinegar solution to remove the residue from soda blasting.

Does soda blasting effectively remove rust?

Epoxy primers vary. Some work fine over a metal surface treated with a metal prep (phosphoric, etc), some manufacturers (Southern Polyurethane being one) do not recommend using a metal prep since it can affect their products adhesion. Read the manufacture data sheets.

I like sand blasting on non-critical panels (floors, inner fenders, suspension parts, etc). After blasting, I like to DA sand or at least scrub with scotch brite pads for the reasons SBerry mentioned... smooth the peaks, remove imbedded grit, etc. I often use a phosphoric based metal prep, Picklex, to further treat before epoxy priming.

I have warped hoods and fenders with sandblasting, and have also had successes. I use a small nozzle, low pressure (60#), fine grit, and blast at a severe angle. Don't stay in one spot too long, go back and forth. If I'm removing paint from a body panel, I just get the majority of the paint off, and not try not to get 100% down to metal. I'll finish removal with a DA sander.
I've gotten more warpage when I blast BOTH sides of a panel.

I don't buy the theory that the HEAT of blasting warps the metal. A panel gets hotter sitting in the sun that it does by blasting. I believe the warpage occurs from the impacts of the media....like when you beat metal with a hammer with a dolly on the back side. Over do it, and you start stretching the metal. blasting does the same thing... impacting the surface can stretch it.

Flat panels are easily warped. High crown panels on a 50's vehicle with thicker metal is less likely to be noticeably warped.

 

[rpcraft]

Panel warp is pretty much going to happen on long flat pieces just because of the heat from the substrate. I think pretty much the only way to blast big flat pieces like that and not heat damage them is going to be the water or "dustless" blasting systems.

 

[Jazz1]

Panel warp is pretty much going to happen on long flat pieces just because of the heat from the substrate. I think pretty much the only way to blast big flat pieces like that and not heat damage them is going to be the water or "dustless" blasting systems.

No warps here and you won't find a bigger panel
My comments are not opinion, they are personal experience