Marvin Posted December 5, 2021 Share Posted December 5, 2021 Hi Has anyone had experience painting stainless steel? I have some external stainless steel that's begining to corrode and I wanted to protect it from further damage. Does anyone have any advice on how to do this / which products to use? Thanks M Link to comment Share on other sites More sharing options...
tonyshouse Posted December 5, 2021 Share Posted December 5, 2021 It does not sound like stainless steel if it is corroding, it it galvanised steel? Link to comment Share on other sites More sharing options...
SteamyTea Posted December 5, 2021 Share Posted December 5, 2021 (edited) There are several grades of stainless. Even our food grade 316 can corrode if we use the wrong cleaner on it. https://continentalsteel.com/stainless-steel/grades/ As for painting, no idea. https://theartsuppliers.com/painting/painting-on-stainless-steel-everything-you-need-to-know/ And some stainless can corrode and fail very quickly in the absence of air. Edited December 5, 2021 by SteamyTea 1 Link to comment Share on other sites More sharing options...
Marvin Posted December 5, 2021 Author Share Posted December 5, 2021 38 minutes ago, tonyshouse said: It does not sound like stainless steel if it is corroding, it it galvanised steel? No it's stainless steel ? Link to comment Share on other sites More sharing options...
Marvin Posted December 5, 2021 Author Share Posted December 5, 2021 41 minutes ago, SteamyTea said: There are several grades of stainless. Yes I knew that and I think this is low grade.We live about 800 meters from the sea and I think that's effecting it, but it's only taken 6 months... Link to comment Share on other sites More sharing options...
JohnMo Posted December 5, 2021 Share Posted December 5, 2021 Get a magnet, if it sticks it very very low grade stainless or carbon steel. Are there any bolts or screws near where you are seeing rust, if they are not stainless they will corrode very quickly and stain the stainless. These should be replaced with stainless unless they are structural. For painting, clean with soapy water, grind surface clean, clean with soapy water, flush with clean water and dry. Use a multi surface primer and top coat. Same approach used for galvanized also. Link to comment Share on other sites More sharing options...
gaz_moose Posted December 5, 2021 Share Posted December 5, 2021 a thin coat of acid etch primer then a paint that is high in zinc. Link to comment Share on other sites More sharing options...
markc Posted December 5, 2021 Share Posted December 5, 2021 22 minutes ago, gaz_moose said: a thin coat of acid etch primer then a paint that is high in zinc. +1 to this as long as the stainless is low grade, do not put zinc near any stainless in 400 grade or above Link to comment Share on other sites More sharing options...
Marvin Posted December 5, 2021 Author Share Posted December 5, 2021 Pictures. Here we go..... particulary visible on corners.. Next is the top... Sort of rusty spots... Back grill where each bar crosses: Going to have fun trying to paint that.. Link to comment Share on other sites More sharing options...
Onoff Posted December 5, 2021 Share Posted December 5, 2021 I believe that welding causes changes to the composition of stainless steel. Link to comment Share on other sites More sharing options...
dpmiller Posted December 5, 2021 Share Posted December 5, 2021 the grille at the back I'm pretty sure is only chromed, mine went a bit brown but when rubbed off it settled down. The corner, it might be worth giving it a rub with scotchbrite just in case the wrong wheel was used when buffing it? 1 Link to comment Share on other sites More sharing options...
Onoff Posted December 5, 2021 Share Posted December 5, 2021 (edited) I tend to use U-Pol etch primer for most things now. However you might consider Hammerite Special Metals Primer. Looks like a thin red oxide. I've used it on aluminium, copper, galvanised steel and stainless and it's pretty good...despite it being made by Hammerite! ? Edited December 5, 2021 by Onoff 1 Link to comment Share on other sites More sharing options...
AdamSee Posted December 5, 2021 Share Posted December 5, 2021 I see something similar every so often. Its not the stainless steel rusting. Its cross contamination from using the same grinding wheel to what was used on a piece of mild steel. Considering the rust is localised to the welded corner, I would assume its this. As for-mentioned a scotchbrite and some stainless cleaner will do the trick. Ironically stainless steel does actually stain, you may be left with a "tea bag" stain. 1 Link to comment Share on other sites More sharing options...
JohnMo Posted December 5, 2021 Share Posted December 5, 2021 That is stainless steel cleaned up with something that has been used on carbon steel, a grinder for example. The normal engineering way to get this off is with an acid gel. Not something you can safely do at home. The stainless is not rusting. The carbon steel deposited is corroding. A local engineering shop may be able to treat it for you. 1 Link to comment Share on other sites More sharing options...
Onoff Posted December 5, 2021 Share Posted December 5, 2021 A lot of the better fab shops separate their mild steel production areas from the ali and stainless using a completely different tool set. This to prevent cross contamination. Basically you get bits of mild steel swarf embedded in a grinding disc then use it on ali or st/st where it rusts. Years back we found if we cut M16 304 studs with a 9" cutting disc the end would rust. The thought that it was overheating. The trick was to then "gently" dress the end with a 4 1/2" grinding disc to get rid of the damaged/overheated area. Times have moved on and we now use thinner slitting discs so might not be so much if an issue. 1 Link to comment Share on other sites More sharing options...
Onoff Posted December 5, 2021 Share Posted December 5, 2021 2 minutes ago, JohnMo said: That is stainless steel cleaned up with something that has been used on carbon steel, a grinder for example. The normal engineering way to get this off is with an acid gel. Not something you can safely do at home. The stainless is not rusting. The carbon steel deposited is corroding. A local engineering shop may be able to treat it for you. Used to tip an acid over welded stainless brackets to clean the welds up where they were discoloured I recall. Link to comment Share on other sites More sharing options...
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