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
How to get Grey patina on aluminum case?
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MASSIVE TYPE IV
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dstar
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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.
BTW, what's wrong wif SHINEY aluminium?
Don
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.
BTW, what's wrong wif SHINEY aluminium?
Don
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MASSIVE TYPE IV
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- Joined: Fri Jul 07, 2000 12:01 am
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Gyouwhy
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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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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
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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