How to get Grey patina on aluminum case?

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Ephry73
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How to get Grey patina on aluminum case?

Post by Ephry73 »

Jake, I have noticed a few of your engine blocks with a very nice gunnmetal grey patina. How do you get that? is it paint? or some type of acd based solution?



Ephry
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MNAirHead
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Post by MNAirHead »

If jake doesn't reply... I'll dig up the chemicals that will dull aluminum... we have the chemist visiting in a few days...
MASSIVE TYPE IV
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Post by MASSIVE TYPE IV »

Thats what I do.. We dull the case- A lot of it happens in the cryogenics processes as well.
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dstar
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Post by dstar »

409 will turn Aluminium gray, but it takes about an hour.

There used to be sold an engine cleaner that was causic and told ya to wear gloves, THAT will work in 5 minutes or LESS!

Don't use acids on Alu, use Alkalis....(sez caustic on the bottle/can)

Try it on the botton of you *Bachelor's Special* frying pan.... not the good
one.
:wink:

BTW, what's wrong wif SHINEY aluminium?
:twisted:

Don
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Ephry73
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Post by Ephry73 »

hahaha. Good enough. I am trying to get all these parts for the 2072 engine, and I love the look of the grey case(dont ask me why) i figured I can do the cylinders too, since they are aluminum.




Ephry
Tristessa
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Post by Tristessa »

Get a cat to pee on it. Cat urine does *amazing* things to aluminum. :lol:
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Ephry73
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Post by Ephry73 »

Maybe I can get some use for our useless cat after all :D


E
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MNAirHead
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Post by MNAirHead »

The problem is trying to fit an engine block in a potted plant or your shoes.

The egyptians were all Fd up... worshiping cats?

T.
MASSIVE TYPE IV
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Post by MASSIVE TYPE IV »

I sometimes paint cases that are stained and won't come clean- But not black.... And its more of a cast metal coat than paint.
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Ephry73
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Post by Ephry73 »

l don't want to paint the cae Don. ;)


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Gyouwhy
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Post by Gyouwhy »

i have had quite a bit of experience painting in general. and if you go to a specialty model shop or art supply like Kit Kraft here in Laurel Canyon California they have a vast variety of patina chemicals to dull or change the look of the metal i have use these in the past and have done well with them but the one warning i have to give is try it on a scrap first then seal the chemical process after so that it does not continue to patina the part or parts.
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raygreenwood
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Post by raygreenwood »

Painting the case with normal enamels....no matter the color, forms a heat barrier due to the pigments and minerals contained in it. It holds heat in. Not all paints are bad and do this...but most do. You must be careful what you use....and test it for how fast it radiates heat compared to bare metal. Heat shedding paints are different animals. They are generally not designed to abosrb heat...just get rid of transmitted heat from surfaces they are on.
While its true that the darker the surface...the more heat it attracts, it does not mean that it will radiate that heat well.
There is the problem.... that a black case will draw heat in from external sources, like the exhaust. Black attracts heat from any heat source and from any direction (inside and outside), as long as radient heat in the form of infrared radiation can traverse that gap. It does this because...the color black...unless its glossy, does not have the natural ability to reflect most of the light spectrum. That spectrum includes infrared....which is heat. Gloss black...depending on the degree of gloss and the angle of incidence of the light/heat waves...can reflect away upwards to 30% of the heat...or more.
The flatter the black surface...the more it is capable of absorbing.
If I were to do anything to a case or metal surface to color it and absorb or deflect heat...I would either anodize it black...or darken it by staining it like you are thinking, or parkerize it. This is because these three types of coating have an intimate electrochemical, molecular bond at the surface metal....that does not block normal ductility of heat transfer.
Also, it should be masked..to make sure that the inside surface is not blackened. That would absorb heat towards the inside.
There are some powder coatings....and some flame sprayed coatings, that are probably good to coat engines with. The pigments in them ar polymer based, not mineral generally. They meslt and fuse into a continuos coating, giving less internal heat reflectance and a "tighter" adhesion to the surface. Ray
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Daniel G
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Post by Daniel G »

I guess I will just put a chemical patina on it or leave it natural. I knew this was a dead horse, Don, but I figured I would butt in and steal the thread... :lol:

Daniel
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Post by Guest »

Daniel G wrote:I guess I will just put a chemical patina on it or leave it natural. I knew this was a dead horse, Don, but I figured I would butt in and steal the thread... :lol:

Daniel
BUWAHAHHAHAHAHHAHAHAHAHA!
Post whore!

Don
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