Smog Tube Coloring

[Mr. Chevy]

I just picked up a set of reproduction smog tubes. They are solid black in color. Has anyone "nailed down" a specific color or combination of colors to use on these to replicate the original brownish coloring??

Thanks... Rich

[ORIGLS6]

I wonder if you could use the same process gun makers use when they "Brown" rifle barrels?

[rpoz11]

I think I used Silver Cad.

Don't add the Brightener finish.

Consider the heat issue to the chemical selected for your finish.

I tried a different finish and it was too bright and it discolored do to heat. I forget the name of this one; Silver Zinc - I think.

[CamarosRus]

This a great detail subject that I've thought about plenty over the years.

I'm thinking that the brownish look often seen may be as a result of heat.

Seems that Ive read one source or another stating that Black Zinc was the coating. I've never had anything Black Zinc plated so cant attest to its appearance.

FYI, this would not be same as Manganese Phosphate, Zinc Phosphate or Black (cant recall now???)

[rpoz11]

[ QUOTE ]
Manganese Phosphate, Zinc Phosphate or Black (cant recall now???)

[/ QUOTE ]

Most of the Manganese Phosphate (sp) that I found on the parts off of my Camaros I tore down over the years ended up under painted parts; whether it was pulleys, brake line bracketry, the obvious nuts and bolts throughout the chassis and sheetmetal areas and/or what-have-you.

I cant speak for timeline assembly variations, as we are dealing with months and months of these cars being built as well as suppliers choices at the time.

I just dont see a need to base the Smog Tubes in "MP" prior to any Cad finish I used; and for that matter - as I am no expert on chem plating - I dont know that one would receive the proper finish expected when using any "MP" under a Cad finish plating.

However, I could forsee one bulk assembly of these Tubes seperated for assmebly on the production line, and another bulk assembled for replacement over the counter warranty or replacement needs over time. The latter could have been "MP" based then painted Black to survive the shelf time and weather exposure until they were pulled for use months to years later. Then I could accept the latter idea.

The tubes were raw, assembled and sweated together and were an "eye view" location piece in the engine compartment.

These were mostly in a Silver finish; ie Silver Cad.

Any "MP" finish I found sometimes didnt get the paint on it, like under car locations. It is under my experiences building these cars that several parts were assembled in an "MP" finish without any paint on them prior to installation and some appeared to be ghosted over in that Chassis Black leaving some surfaces painted and some exposing surfaces with just the "MP" showing.

[Mr. Chevy]

Thanks fellas...

Rich

[Unreal]

The ones I got from Bill Hodel were sort of a brownish olive green. The fact that Hodel did them does not make them correct, but he would at least know what the correct color should be.

[SSRSBOB]

Black Zinc,

Bob

[miket1]

i looked at Jerry's site, he has pics of correctly restored engines, they are black.

[CamarosRus]

Does anybody reading have any actual, specific experience having smog tubes BLACK ZINC plated and run on engine.....

and also are most smog tubes blocked betwen the flare and the exhaust manifold ?????