OT Clear Coating Black oxide Finish?

Fear Factory · Feb 15, 2015

I have built 2 tables all from mild steel it has 2 pieces sized 1200x600mm folded for the top and bottom, I Sanded these pieces up to 1200 grit before being black oxided,
originally I thought Black oxide Should be enough to stop rust with a coat of wd40 or what not every week or so I was wrong, I have had them covered up under a sheet and you can already see tiny dots
forming of what I assume is the start of rust, Is there or has anyone had experience with a clear coat that you could practically wipe on? Being black oxide I think I am not in luck as I don't think anything will stick
to the oxide could be wrong? I planned on selling these but, if I Can't fix this problem they will have to be pulled a part and powder coated which would put me at a loss, or I just keep them I love the raw look but I know people will complain if they start rusting right away.

steve-l · Feb 15, 2015

I assume by black oxide you mean gun bluing. However, there are several processes that can create this finish. Which one did you use exactly? No matter what method you used even though some are more durable than others, none are appropriate for a high wear surface. I even think mild steel in any form is rust just waiting to happen.

Fear Factory · Feb 15, 2015

steve-l said:
I assume by black oxide you mean gun bluing. However, there are several processes that can create this finish. Which one did you use exactly? No matter what method you used even though some are more durable than others, none are appropriate for a high wear surface. I even think mild steel in any form is rust just waiting to happen.

I sent them out, they are hot blackened not like room temperature blackening, which is supposed to give somewhat enhanced rust resistance but I have learned that the rust resistance is well shit regardless, I think I have done my self in...

steve-l · Feb 15, 2015

A hot salt bath bluing process is the best method, but all these methods is controlled corrosion and unless thoroughly cleaned of the bluing salts, corrosion will continue well past the tank time and no preservative, oil or wax will stop it.

rwbaldwin · Feb 15, 2015

WD40 is pretty poor for this kind of application. A good dewatering oil will give better results.

Making the tables from SS would have been better.

adama · Feb 15, 2015

Wax can work wonders, but you need to get the parts clear of any oil first, helps if its a solvent based wax. Still offers nothing like the protection of powder coat, but might make what you have usable.

Next time do your home work on surface finishes its all over the web. Any type of steel bluing is very much a high maintenance finish.

Fear Factory · Feb 15, 2015

rwbaldwin I thought about ss but material cost would be to high

Adama when you say wax do you mean just like hand applied, like Car wax this crossed my mind as well, and yes I have learned my lesson I always Say to my self "Don't Assume.... KNOW!" well I assumed and got it wrong :dopeslap:

martinberryman · Feb 15, 2015

I'm not clear if this is for industrial use, or furniture.
I recently looked into this for decorative finish on furnishings and other architectural fittings, and just submitted samples to our client. If this is for decorative purposes only, you may get away with cleaning off all of the oils using a strong solvent based degreaser (like Tumbler), and then clear coating with a post-catalysed conversion varnish or lacquer that uses an acid as the catalyst. The advise our finishers got from our material suppliers was that the acid in the catalyst would work the same way a self etching primer does in getting some bite into the steel substrate. When I was doing my research, I looked at other work that different vendors had supplied to the same client, and it was not holding up well to abrasion, but the coatings were not lifting off the surface.
Martin

jim rozen · Feb 15, 2015

"I thought about ss but material cost would be to high"

Did you factor in the cost of hot bluing?

If you took the money used for that, and put it into materials,
would the equation favor SS?

dian · Feb 15, 2015

hm, if i polish a piece of mild steel and come back 6 months later, there is no rust (no oil on it). i believe some of the pieces have been around for 2 years and still no rust. is that table outdoors? maybe its just a different climate.

challenger · Feb 15, 2015

Sounds like the steel was "Parkerized"???
Definitely won't come close to stopping rust.
I don't know other pertinent details but I've found that bees wax is great for preventing rust.
I have done a good amount of home parkerizing and the finish looks great if preparation etc is properly done. Small parts seem to hold up, and look better, when soaked in heavy weight gear oil-not synthetic.
How are these tables being used? Purpose?

challenger · Feb 15, 2015

dian said:
hm, if i polish a piece of mild steel and come back 6 months later, there is no rust (no oil on it). i believe some of the pieces have been around for 2 years and still no rust. is that table outdoors? maybe its just a different climate.

Huh? Polish with what? Paint?

dian · Feb 15, 2015

no paint. polishing to mirror with compound. no rust here.

robert123 · Feb 15, 2015

challenger said:
Sounds like the steel was "Parkerized"???
Definitely won't come close to stopping rust.

Parkerizing is another name for a zinc or manganese phosphate. Black oxide is a different process. Neither is great at preventing rust. Black oxide is a very thin coating that provides little corrosion protection by itself. It does have pores that will hold oil and help to prevent rust, but if gets wet and the moisture is not removed quickly, rust will start.

I would look at zinc plating with a black chromate for aesthetics or a good paint.

Whetstone · Feb 15, 2015

I make a lot of small tables that have a black oxide finish that I seal with wax. While is is a beautiful finish it is not super durable and still requires regular maintenance. I apply it useing heat. I use a large propane torch, the heat drives out the water and sorta opens up the pores of the metal . I preheat the metal to just shy of smoking when the wax is applied.

challenger · Feb 16, 2015

This is what I do with my fishing knives.
I use bees wax because it has a higher melting point. It still has to be reapplied a few times per summer

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