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General Category => Painting & Weathering Techniques => Topic started by: lab-dad on May 28, 2012, 04:07:37 PM



Title: Blackening / darkening aluminum??
Post by: lab-dad on May 28, 2012, 04:07:37 PM
I need to slightly darken the aluminum pulleys on my drill press.
Everything I have has failed me.
The chemicals i have do darken bur also pit.
I dont want them black but the polished finish is too bright.
Oils?
Goache?

Marty


Title: Re: Blackening / darkening aluminum??
Post by: Mr Potato Head on May 28, 2012, 10:50:30 PM
Go to your local industrial metal supply place they'll have the blackener you need, itís cheap too, a concentrated quart will last you a lifetime!
MPH


Title: Re: Blackening / darkening aluminum??
Post by: Andi Little on May 29, 2012, 01:57:35 AM
Didn't want to say anything for fear of getting it wrong! - But, have you tried "Oven cleaner"? Every time I've got any near ally' it has darkened it considerably, almost a deep gunmetal.

Just thinking.


Title: Re: Blackening / darkening aluminum??
Post by: Design-HSB on May 29, 2012, 04:20:37 AM
Hi Marty,

i think ALUMINUM-BLACK (http://www.brownells.com/.aspx/pid=4941/Product/ALUMINUM-BLACK)the best way for your part.


Title: Re: Blackening / darkening aluminum??
Post by: chester on May 29, 2012, 07:21:57 AM
Marty, had some luck by using Muriatic acid and Hydrogen Peroxide 50/50. Not quite as potent on aluminum as most chemical etchants and can be weakened by using more peroxide.


Title: Re: Blackening / darkening aluminum??
Post by: marc_reusser on May 29, 2012, 05:16:12 PM
Pee?  ::)


Title: Re: Blackening / darkening aluminum??
Post by: finescalerr on May 30, 2012, 01:41:25 AM
Okay, Marc. Your turn. Go stand in the corner. -- Russ


Title: Re: Blackening / darkening aluminum??
Post by: lab-dad on May 30, 2012, 06:08:50 AM
Marc,
Tried that - turned yellow..........


Title: Re: Blackening / darkening aluminum??
Post by: chester on May 30, 2012, 07:55:07 AM
A little off the subject but when I was young I would help my grandfather in his construction business. One Saturday I was given a can full of pee (donor unknown) and told to "paint" the galvanized gutters with it before the finish paint went on. I suspect the thought was it would etch the metal. I have no idea if this is so. I washed my hands thoroughly before lunch that day.


Title: Re: Blackening / darkening aluminum??
Post by: lab-dad on May 30, 2012, 08:51:48 AM
I have heard of the urine helping to promote the green on copper.

At this point i think I am going to leave the pulleys alone, they look pretty good "as-is".
May be just a hint of surface rust on the ones not used often, recently.......
It is coming along, pics soon.

-Marty


Title: Re: Blackening / darkening aluminum??
Post by: shropshire lad on May 30, 2012, 10:10:41 AM
Horse pee will blacken oak shavings , something to do with the ammonia in the pee . Though I suspect you will have to have some pretty potent pee to blacken aluminium .

  Do you want me to send you a pint or two of horse pee to have a bit of an experiment ? ! ? Or is your own toxic enough ?

   Nick


Title: Re: Blackening / darkening aluminum??
Post by: chester on May 31, 2012, 06:50:28 AM
It would be the ammonia if it were white oak. I built some wh. oak furniture that we tented and put ammonia gas into the tent to get a black color. Lye does a number on cherry too.


Title: Re: Blackening / darkening aluminum??
Post by: eTraxx on May 31, 2012, 09:00:20 AM
A while back I got a sample of InstaBlak A384. You can see from the pic this enough of a 'sample' to last me quite a while .. probably forever. The company shows a InstaBlak A385 also - http://www.epi.com/c/black-oxide/aluminum .. there is a button below each where you can request a sample. Might be worth the time.



Title: Re: Blackening / darkening aluminum??
Post by: lab-dad on May 31, 2012, 03:20:58 PM
Thanks Ed,
Dont use the regular (insta black) stuff on aluminum - pitted the hell out of the piece I did.
-Marty


Title: Re: Blackening / darkening aluminum??
Post by: Malachi Constant on May 31, 2012, 04:28:12 PM
For an alternative to the chemical treatments ... some acrylic glaze medium (Vallejo or craft store stuff) and a touch of deep gray acrylic paint.  Mixing the paint with glaze medium makes a transparent paint layer -- TINY touch of paint on the first round to check the effect ... let dry for several hours (takes a lot longer with glaze medium) ... go back with a slightly denser coat if needed.  And, for even more transparent coat ... touch of Vallejo black ink in glaze medium ... there won't be any opacity to the color, just a tinting effect like looking at it thru sunglasses.  8) -- Dallas


Title: Re: Blackening / darkening aluminum??
Post by: lab-dad on June 01, 2012, 05:48:19 AM
OOOHHH!!!!
I like those ideas Dallas!
Going ot get some of that stuff and give it a try!
Thanks!
-Marty


Title: Re: Blackening / darkening aluminum??
Post by: Malachi Constant on June 01, 2012, 02:09:27 PM
Couple of notes on the glaze medium:

-- Used in THIN layers, it dries nice & flat.
-- It takes MUCH longer to dry than ordinary thinned or un-thinned acrylics and even longer to actually "cure" (set)
-- If you go too heavy, the glaze will take on a gloss

So:  go easy ... allow ample drying/curing time (I'll usually allow overnight) ... and resist the urge to mess with it before set.

If you screw up, go too heavy & get a bit of gloss (which I still do occasionally) ... let it fully set, then a couple light coats of Tamiya TS-80 Clear Flat spray will kill the gloss.  (And, in general the TS-80 beats the crap out of Testor's dullcoat ... but that might just be my very biased opinion!)

Cheers,
Dallas


Title: Re: Blackening / darkening aluminum??
Post by: searoom on October 29, 2012, 03:18:45 PM
Urine has been a traditional non-ferrous metal patina for centuries.

 ;D


Title: Re: Blackening / darkening aluminum??
Post by: W.P. Rayner on October 29, 2012, 08:27:51 PM
Horse pee will blacken oak shavings , something to do with the ammonia in the pee . Though I suspect you will have to have some pretty potent pee to blacken aluminium .

  Do you want me to send you a pint or two of horse pee to have a bit of an experiment ? ! ? Or is your own toxic enough ?

   Nick

A video clinic on this process would be most welcome Nick, especially the part where you convince the horse to pee into a cup....  ;D ;D

Paul


Title: Re: Blackening / darkening aluminum??
Post by: finescalerr on October 30, 2012, 01:44:28 AM
I think some of you need to go stand in the corner .... -- ssuR


Title: Re: Blackening / darkening aluminum??
Post by: shropshire lad on October 30, 2012, 02:31:07 AM
Horse pee will blacken oak shavings , something to do with the ammonia in the pee . Though I suspect you will have to have some pretty potent pee to blacken aluminium .

  Do you want me to send you a pint or two of horse pee to have a bit of an experiment ? ! ? Or is your own toxic enough ?

   Nick

A video clinic on this process would be most welcome Nick, especially the part where you convince the horse to pee into a cup....  ;D ;D

Paul

    Er , nothing smaller than a two gallon bucket would be suitable . I'll get right onto it ... once I've finished my sojourn in the corner .

    Nick


Title: Re: Blackening / darkening aluminum??
Post by: marc_reusser on October 30, 2012, 04:34:23 AM
Geez...do I have to do all the heavy lifting.

Here you go Paul.

 https://www.youtube.com/watch?v=XKwX5V9eZ-g&feature=youtube_gdata_player (https://www.youtube.com/watch?v=XKwX5V9eZ-g&feature=youtube_gdata_player)


Title: Re: Blackening / darkening aluminum??
Post by: Gordon Ferguson on October 30, 2012, 04:52:16 AM
Marc,

Your attention to detail sometimes leaves me completely gobsmaked  :o ::)


Title: Re: Blackening / darkening aluminum??
Post by: W.P. Rayner on October 30, 2012, 07:56:27 PM
Geez...do I have to do all the heavy lifting.

Here you go Paul.

 https://www.youtube.com/watch?v=XKwX5V9eZ-g&feature=youtube_gdata_player (https://www.youtube.com/watch?v=XKwX5V9eZ-g&feature=youtube_gdata_player)

You know, this just proves that there are too many people in this world with video cameras and too much free time on their hands...

Paul


Title: Re: Blackening / darkening aluminum??
Post by: Lawton Maner on October 30, 2012, 08:47:21 PM
White Oak + Ammonia = Fumed Oak.  Think about the Stickley furniture from the late nineteenth century.  In the woodworking industry, the effect is done by placing the completed piece of furniture in an airtight box and exposing it to ammonia fumes for up to 24 hours.  At the end, when the piece comes out of the box, it is a greyish colour.  Rubbing a coat of wood finishing oil on the piece brings out the rich almost black colour associated with Stickley.  Fuming cherry will make pale pink new cherry timbers look as they have over ten years of patina on them over night.

I once fumed an entire room of white oak bookcases and paneling because after the client saw the finished room. he wanted it a bit darker.  We placed trays of blueprint developing grade ammonia in the room and checked it every other hour until the desired colour was reached.  Since there was a lacquer finish on all of the wood the change took several days.  BTW, don't try it at home, because that much ammonia in a closed space can KILL.


Title: Re: Blackening / darkening aluminum??
Post by: Tom McInerney on February 23, 2013, 10:12:56 AM
Went to a clinic last year at the Craftsman Expo and Brett buffs his blacken it back off with a wire brush to get the color he wants. Tom