Technical Darkening Aluminum Experiment

Just thought I'd share a little experiment I did last night. I have a pair of 5-spokes that I wanted to darken up since blasting them made them way to bright looking, and I tried the graphite spray that I hear a lot about on here... thats a no go for me. Wipes off to easily for how often I am manhandling my car. Looks OK before it wipes off, but just too delicate for me.

Another thing I read about was oven cleaner, but found absolutely zero pictures of the results. Well, here's one! It actually worked great. I tried it on an old valve cover last night. I sprayed it on, let it soak for 15 minutes, rinsed... not dark enough so I applied it again and let it sit for another 10 minutes, rinsed.. Perfection! To me, anyways. I let it dry on the kitchen counter overnight. This morning it was covered in white oxidation! That's fine, however, since it buffs off with a dry shop rag. I then wiped some penetrating oil on a section, let it soak in, buffed that off with a dry rag, and then let it dry.

So here the valve cover. Top right is how it oxidized, top left in penetrating oil directly applied to the oxidation. The next are between the ribs below that is where I bugged the oxidation first, and then oiled it. Below that, just buffed with no oil. The shiny spot below that is raw aluminum, lightly buffed by hand with a rag and some oil. Then just raw as-cast aluminum with no treatment whatsoever other than sitting on a shelf for 20 years.

This afternoon I plan on trying it out on an old slot mag, and I'll post back with those results!

 

Not sure exactly the look that you are after, but after blasting aluminium parts with used gl*** beads I just use one or two applications of Gibbs. I like the color, no harsh chemicals, and it's easy to touch up if needed. On parts in general, and especially critical parts, after any chemical treatment a neutralizing process should be used to stop any additional chemical action that might compromise the part. I use a lot of vinegar for rust removal which is not very caustic but always use a baking soda wash to neutralize.

 

Yes on Gibbs!

 

I'm going for more of a mag-ish look. I have oiled a pair of slot mags, and it does look good, but I want a little darker than that.

 

We soaked, (10-15 minutes), a clean, aluminum intake manifold in muriatic acid, (quickly rinsed with warm water after removing), and got a nice, dark-ish, magnesium look

 

I saw some darkening products online but they are all coatings and thus subject to scuffing.
For this reason, I won't name them or suggest they could be used on wheels. Just thinking of doing a touch-up makes my hair stand up regarding what that would look like.
But I'm not a "patina on wheels guy". I like 'em shiny on otherwise dilapidated vehicles. And I only wear worn jeans with new shoes and a new belt........ Yea, I'm that guy. So your tastes may differ.

 

I used oven cleaner on Aluminum wheels several years ago. Thought it was a bad idea.

 

I have Romeo Palemides' 2-piece aluminum wheels (made esp. for F100 Fords)
My Dad gave me one set, the other I bought, for my other truck (F1)
I had some Meguiar's aluminum wheel cleaner, so used it on the right front: Didn't like the 'foaming' I saw, so rinsed it off and... Cast part (unpolished) got lightly pitted, (!) so I then read the label on the can:
"For treated and polished" Rats! Big dumb RATS!!! I spent 2 hours sanding the rough part so it didn't scream out...
Yes, Baking soda with the water rinse. Probably saved the day.
I have used oven cleaner on aluminum before, but no more. Way harsh! Plus better have Baking soda near at hand.

 

The problem with using harsh chemicals on cast aluminum is that it can be porous and the stuff can literally soak 'into' the metal. The longer the soak time, the more likely it will continue to eat away at it.

 

I have a Harley rocker box that is badly etched in one corner. It was on the rear jug and up under the end of the fuel tank. The guy that had the bike used oven cleaner to clean the aluminum and never cleaned up that particular corner because it was under the tank. It's now on the front jug...in all it's glory.

 

Here's an update! Dried several variations on soak time, on both fresh blasted areas, as well as an area that I rubbed down with a red scotchbrite pad to smooth out the roughness from blasting.... didn't like the results at all! Much, much less uniform than the die-cast valve cover I initially tested. You can see in this picture that the parts that didn't get darker actually turned lighter in color, almost white! So, now it's onto plan B. Not sure what plan B is yet, though...

 

This may seem odd but cheap dishwashing machine liquid and let the freshly blasted aluminum sit in it, the longer it sits the darker it gets.
My buddy is experimenting with it and it does work

 

I found a while back that polishing my cast aluminum hubcaps with the different grades of scotch brite pads followed by 0000 steel wool after gave it a nice aged but uniform look. Here is the link to my post about it.
https://www.jalopyjournal.com/forum...shine-how-to-polish-to-a-dull-finish.1063635/

 

I have an old flatty aluminum intake. Never been blasted, had decades of nasty gas n oil stains. No solvents or acids of any kind would work, except paint remover, ****ed it right out. On the underside I left it longer and it didn't really discolor much. No blast surface just in "Henry" condition now.

 

This might be the true path to endarkenment. Pic here stolen from @SamIyam 's instagram - he bead blasted then ran the intake in the dishwasher. I've got a set of E-T 1s I want to do the same to. Have to take them into work on a weekend perhaps!

 

Alodine is designed to be used on aluminum to help prevent corrosion it will give it a golden cast, if left to soak longer will give a light brown.
Prolly not what you’re looking for

 

I use a mag wheel cleaner (acid based) that bleaches the aluminum out white. Sometimes I love the look. Sometimes I do not. I discovered that you can use lemon pledge to keep the clean look. I also discovered on aluminum engine parts that you have to let it set for a day or so before you fire it up. Or you can light it right off and it will get a magnesium look. I got a pair of big ol boxy rocker covers on a motor that look magnesium and have held that look for several years. Found out my accident. LOL

 

I bead blasted my early Corvette valve covers and soaked them with WD40 and wiped it off. It darkened them nicely. At shows, folks asked if they were magnesium.
My buddy used to sandblast intake manifolds and then wash them in his dirty solvent tank and blow them off with the air gun. It got rid of the “too white” look.

 

the color would look good on wheels. Reminiscent of magnesium treated with DOW 7

 

That wasn’t done by accident as evidenced by the flames pattern etched into it.

 

I did the flames in an attempt to do something with the issue. I've had many questions about it and the bike is a Hot Rod, so it fits in A-OK by me.
Used an engraving tool to do the flames

 

Just to put some explanation into the discussion. Oven cleaner is sodium hydroxide. Vinegar or some of the "wheel cleaners" are acid. Acid (H+ ions in the solution) is opposite of hydroxide (OH- ions in solution). Hydroxide will etch aluminum, as evidenced by some of the results discussed, but it will not necessarily darken the surface without something added like the oil. It is a fresh surface, not one with aluminum oxide as an old part. Alodine is a chemical conversion reaction that produces an oxide layer, which also has some chromate which gives the yellow color (and improved corrosion resistance from the chromate). Acid solution will remove any oxide on the surface. One thing for sure, if you have any heavy oil/grease on the surface, remove those first best you can. Acid or alodine will not remove the oil. Oven cleaner or dishwasher detergent will remove oil, but best to get as clean as you can first.

So what does all this mean? Just that there are different processes going on. I don't have a suggestion on how to darken the aluminum. Not sure what the dishwasher detergent has in it that causes the color.

 

Has anyone tried experimenting on castings with alodine 1201? I know it works great on regular sheet and bar stock.

 

This is dishwasher liquid diluted in water to be able to spray or rub on or just straight dishwasher liquid ? I’d love to darken these solid rockets

 

I left an autolite 4100 carb body in a 5 gallon pail of NAPA carb cleaner, the new stuff

Forgot it was in there, several months
It is dark grey now


Ricky.

 

Post #53 thru the end of the thread.
https://www.jalopyjournal.com/forum/threads/staining-alum-wheels.974404/page-2

 

He said he bought the cheapest brand he could find, dumped it in a tub and stuck the wheel in it, I ***ume you could brush it on though or try and dilute it and spray it on.

 

I thought I'd be clever many years ago by washing automatic transmission parts in a dishwasher.
All of the aluminium parts came out nearly black ..... OOPS.

 

Aluminium (aluminum) can be anodised in a huge range of colours and hues. Has anyone tried anodising?

 

So here is my before: