Electronics > Mechanical & Automation Engineering

metal marking aluminum for paint adhesion? (magnesium nitrate electrolytic DC)

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coppercone2:
So you have aluminum primer, alodine, sand blasting, etc. All kinda annoying.

But what about electrolytic marking of metal to make a base for painting?

Its easy. Brush on with a carbon brush.

The chemical in the electrolytic brush etchant is magnesium nitrate.

If its used for stencils and shit, it should be a pretty uniform coating, and also fairly tough. Do you think this might make a good substrate for paint? I would need to buy it to test it, and I have no idea what the hell its doing.

Then maybe I can use whatever the hell paint and or primer I want.

Psi:
Generally just giving things a good sand with like 320 grit will make a good surface for the primer coat to stick too.

There are some exceptions that need special treatment, like concrete, but mostly
you can just sand, clean with wax and grease remover and then paint.

coppercone2:
I am kind of thinking that this has the potential to be some really badass pre paint coating.


I removed the aluminum etching primers b4 after a few days, and the aluminum looked untouched honestly.

You have no idea how conveniant this process is for some weird crap that has say some jaw marks from a vise, irregular edges, etc. On a simple surface it might not be worth it, but when you start having to need dremel brillo brushes and other stuff, its very appealing.Especially with gap filling regular primer.

also, stuff like perforated plate. For vent covers etc.

Also same question for steel. Some people claim mill scale makes paint hang on better. How about electrolytically marked regular steel for painting?

I am wondering if it might increase durability.

jpanhalt:
You have not given the alloys you use.  They do differ. I am most familiar with using alodine on Alclad.  If you don't see a change, then you didn't do it properly.  The same applies to 6000 series.

A simple, clean, and green method of prep is simply to let the aluminum sit outdoors to weather for  as long as it takes.

As for your proposed method, it would seem that prepping with an electrified carbon brush versus being able to spray or immerse in a prep would give a less consistent coating.

coppercone2:
a thick coating of paint thats sanded (where possible) afterwards, I am not too concerned about non uniformity that is much less thicker then the paint layer, but how well that paint stays on.

Alodine makes a change, the self etching primer does not really do anything (wash it off a while later after you paint it). Compared to the etching you get from like alumiprep its a joke IMO.

However, I don't want to deal with alodine. That is a huge hassle. This electro etching thing is not a hassle.

I just wanna know how electro marking works as paint prep.

I never actually saw much of it. it just seems promising, given the mill-scale paint fan club. The post phosphoric acid not polished but tarnished aluminum reminds me of mill scale on mild steel to a small degree. It feels rough. I assume the magnesium nitrate one would be even better.

and the alloy can be anything. if the same stuff works on both stainless steel and aluminum in the data sheet, I assume it will work for most common kinds of aluminum. The electrobrush process is absolutely kick ass. I want more from it. I am waiting for that can of aluminum primer paint to go flat and piss me off at some random time from now.

I also think you can probobly make some super electrolytic degreaser step, that might not be cosmetic, but I imagine that TSP mixture I saw some where on the forum a while back might really degrease the shit out of parts. I am hoping to spritz it off with distilled water in a spray bottle after all the other steps and have it ready for painting without the ultrasonics and alcohols and other crap

the optimal result would be electrocleaning (and maybe degreasing if thats not good enough with some alkali), marking, rinsing and painting. maybe with just a top coat if its good enough without the primer all together. wishful thinking maybe but its worth investigating

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