Surface rust on steel

[Zzz]

I have some areas of my quickbuild fuselage that I stripped bare to weld onto. My garage is heated and is very dry, but my fuselage did spent many nights in an open air shop over the summer here in oregon, and developed quite a bit of surface rust on those weld joints.

It's back in my dry warm garage now, but my question is: Will rust continue to corrode the steel in the absence of moisture? Should I make a priority of blasting it clean and priming it? Or just leave it until I'm done with all welding and mock assembly and ready to final coat the fuselage, which could be another year or 2.

Z

[Mark Goldberg]

Personally, I would at the least scotch brite the rust off and spray some Rustloleum rattle can primer. Their red Rusty Metal primer is OK. Easy to use. No reason to let the rust grab a hold.

[Battson]

Personally, I would at the least scotch brite the rust off and spray some Rustloleum rattle can primer. Their red Rusty Metal primer is OK. Easy to use. No reason to let the rust grab a hold.

These were my thoughts exactly. Simple to scratch the paint off again when you're ready to weld.

[svyolo]

The oxygen is what makes it rust. If you are not ready to finish it now, coat it with something to seal it and the rust will not get worse.

[Zzz]

The oxygen is what makes it rust. If you are not ready to finish it now, coat it with something to seal it and the rust will not get worse.

It does, but requires moisture. I've had bare steel parts in my warm shop for years without rust. It's not particularly humid here in Oregon. But even in the summer here with the temperature drop we get some dew outside.

Even the tops of my machined shock pistons where the 1/2" aurora bearings thread in have some light rusting. I recommend people find a way to coat those.

I just wondered if rust had already formed, will it advance any faster than initial formation. Anyway, good advice, thanks. I'll clean up the bare and coat it.

[svyolo]

Rust on steel is not as "protective" as aluminum oxide is for aluminum.

[Chewie]

I've had bare steel in an unheated garage for a few years with no rust, garage door open multiple times a day. 90%+ relative humidity outside in the winter months but because it's cold, the absolute humidity and total mass of water in the air is still quite low. I'm not sure what matters most to rust, but I wonder if shop temperature makes a difference.

[Zzz]

I've had bare steel in an unheated garage for a few years with no rust, garage door open multiple times a day. 90%+ relative humidity outside in the winter months but because it's cold, the absolute humidity and total mass of water in the air is still quite low. I'm not sure what matters most to rust, but I wonder if shop temperature makes a difference.

I think there's bare and then there's bare. Still with mill scale seems a little more resilient than steel I've brushed down for weld prep.

[Battson]

Should patina on steel be considered corrosion and treated as such, like rust, or just the steel normalising it's surface condition to a stable state?

[Chris In Milwaukee]

I thought that I recalled one of the weekend-morning car shows using this stuff on his projects while in between welds for corrosion protection before final finish:

https://www.rustoleum.com/product-catalog/consumer-brands/stops-rust/rust-inhibitor

https://www.rustoleum.com/~/media/DigitalEncyclopedia/Documents/RustoleumUSA/TDS/English/CBG/Stops%20Rust/SRT-19_Stops_Rust_Rust_Inhibitor_Spray_TDS.ashx

I can't really tell from the product description, however, if this is like a clear paint, or if it stays wet like an oily coating.

[whee]

What about using 'Weld-Through' primer? Stewarts mentions using it in their videos.

https://www.amazon.com/SEM-39783-Weld-Thru-Primer-oz/dp/B00063ZPBU

[geraldmorrissey]

I've coated steel with Dykem with good results. Washes off with acetone.
Gerry
Patrol #30

[lsa140]

I've never found a satisfactory solution for temporarily protecting steel that still requires additional welding. A light coat of primer works but can be a pain to remove if the parts has a lot of nooks and crannys. I'd like to find some type of light oil that could be easily removed with denatured alcohol.

[Bdflies]

I've used LPS 3 before. http://www.lpslabs.com/product-details/612
I'm pretty confident that it would provide the protection y'all are looking for. It does leave a waxy, non drying coating, but it's not a primer or paint, so it's a lot easier to remove. I can't swear that denatured alcohol would remove it, but I'd guess it would work.
BTW, if you don't see the "3”, don't get the 1 or 2, thinking it's close enough. They're not the same.

Bill

[lsa140]

I'll pick up some LPS3 and give it a try. It looks like CRC and other manufacturers make similar products that leave a then waxy coating. I'd like to find some kind of aerosol that had solvents suspending a small amount of oil. You could light mist parts awaiting further fabrication and quickly clean them up with alcohol. I know WD40 has a little bit of oil but evaporates quickly. The coatings like LPS3 that leave a more waxy surface could be used for longer term storage. If fabrication is finished a light coating of primer could be quickly sand blasted off when you are ready for final prep and paint.