Millscale on Hot Rolled Steel - bike hauler/ general purpose trailer build

[jwiereng]

What are some ideas about millscale on hot rolled steel before painting ?

One option would be media blast $200

Chemical stripper ($??) messy DIY

Wire brush to remove loose scale and rust, most scale would remain. And primer and paint.

Let me know your thoughts and experiences

 

[Hillbilly Heaven]

Flap wheel on your right angle grinder.

 

[ttengineer]

Wire brush head and flap wheel on an angle grinder will do wonders if you ask me.


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[old_CWO]

I have had good luck with an abrasive wheel for the side grinder that is sort of like a really beefy scotch brite pad. They can be purchased in the 3M brand from body shop supply stores but the Harbor Freight nylon abrasive wheels are almost as good for a lot less money. These wheels quickly remove rust and mill scale but leave you with a nicer, more polished looking surface than the flap wheel does.

They can also really burn off the bubba bondo body repairs; don't ask me how I know....

 

[DaveInDenver]

My feeling is, especially for something like a trailer where it doesn't have to be absolutely beautiful, is degrease, wire or flap wheel and wipe clean. Then prime and paint. I personally haven't done anything more than phosphoric acid, which is pretty good at removing mill scale.

I figure mill scale that is tough to remove is no worse then at adhering to metal than primer and paint. So it's mostly about knocking loose stuff off and making it mostly smooth.

 

[hogdoc]

A powder coater will media blast it all off before coating!

 

[jwiereng]

Powder coating company said,

“To media blast 1 hour…$200

To apply fusion bonded epoxy base coat and top coat in a standard polyester$350”.

I think I have a budget closer to DIY Tremclad.

 

[brp]

I would "DA" or "vibe" that. "DA" stands for dual action, rotation and orbital action, basically an orbital palm sander. It is easy, cheap, quiet, effective. A DA is nice because it is a very forgiving power tool. You can catch an edge and it won't rip your hand off like a grinder, it is just glides and is really easy. You could hold it upside down in one hand to get the undersides. My 2 cents

A sander like this

Harbor Freight Tools – Quality Tools at Discount Prices Since 1977

Harbor Freight buys their top quality tools from the same factories that supply our competitors. We cut out the middleman and pass the savings to you!

www.harborfreight.com

and an abrasive like this, choose whatever grit you want.

Harbor Freight Tools – Quality Tools at Discount Prices Since 1977

Harbor Freight buys their top quality tools from the same factories that supply our competitors. We cut out the middleman and pass the savings to you!

www.harborfreight.com

 

[RagnarD]

A quick wire brush, wipe with ospho, rattle can.

 

[jwiereng]

DaveInDenver,

What’s your recipe for using phosphoric acid? I have access to 75%. I tried a small test piece by brushing some on with paint brush followed by a water rinse. It did remove some rust but did not end up clean shiny.

How long should the H3PO4 be left on the steel?

It is pretty potent stuff, I’ve seen it erode concrete pretty quick. I guess it’s best to do the frame on the grass rather than the garage or driveway.

Do you neutralize the acid after application?

 

[honda250xtitan]

i just wiped down the square tubing with acetone, the panels i did a quick sanding with a palm sander and angle grinder /flap disk then some acetone. Roll on bedliner adheres just fine, any spots that need touch up i rattle can it. It's a homemade trailer built to be abused ?

 

[DaveInDenver]

DaveInDenver,

What’s your recipe for using phosphoric acid? I have access to 75%. I tried a small test piece by brushing some on with paint brush followed by a water rinse. It did remove some rust but did not end up clean shiny.

How long should the H3PO4 be left on the steel?

It is pretty potent stuff, I’ve seen it erode concrete pretty quick. I guess it’s best to do the frame on the grass rather than the garage or driveway.

Do you neutralize the acid after application?

All I've ever done personally is pickling solutions, so maybe 15% or 20%. That I wash off with water and, no, it doesn't strip it to bare bright steel. I think that would require tanks and dipping in something highly concentrated, probably HCl (which reminds me, have you tried muriatic acid?). I think your most cost effective option if you want bare steel is having someone media blast personally. But I wouldn't worry that much.

 

[180out]

Remove weld splatter with sander, wire brush welds to remove any scale, wipe down with acetone/mek/ or any oil free solvent. prime with DTM primer(direct to metal) paint and enjoy. make sure any sealed tubing has a small drain hole to allow moisture out especially if you live where it freezes.

 

[ottsville]

How about clean the welds and spatter, wire wheel any loose stuff, wipe down with anything to remove grease and prime with por15?

 

[Bayou Boy]

I'm just here to say that I really like that trailer frame. Super cool.