Black oxide problems

[destroyer125]

Im trying to Do black oxide on a batch of screws, I have tried the black oxide from caswell, and it is hardly blackeneing. And the ones that do, I can scratch the coating off with my fingernail

[lcaswell]

What sort of steel are they? What's your prep and parameters?

[destroyer125]

I Tried 8-18 Stainless and 316 stainless. First I attempted a few screws in a tiny sample. They did blacken but the coating is anything but durable and comes off while im drying them. I attempted an etch with muratic acid on the 316 and 8-18 stainless in various small experiements.

After trying and trying to get them to work on several different boxes of screws. This is pretty much what they all look like

[lcaswell]

Hmm, well....black oxide doesn't work on stainless. You need our Stainless Steel Blackener.

[destroyer125]

Sorry I didnt clarify, but I am using the stainless steel blackener not the iron/steel blackener

[HotRod9mm]

Originally Posted by destroyer125

.... I am using the stainless steel blackener....

Did you ever get the 370 to work? There is little or no information about the 370, not even a tutorial. I have tried just about everything including the countless one line instructions via email from tech support and the $320(4x$80ea) worth of barrels I've ruined really sucks(and I don't mean cosmetically either, they cannot be used because they are etched VERY badly). I even purchased some industrial grade muriatic acid(80%) as suggested and nothing seams to keep the parts from looking like they have leprosy(like your photo of the screw) or to keep from just wiping what little spots of black there is off with a rag?

TIA

[destroyer125]

This stuff is anything but durable. I cant get the stuff to work at all. I tried last night with a few other screws, same thing.

[lcaswell]

Can you please provide the tech support ticket numbers for this problem. Stainless steel blackener shouldn't rust the parts like that. Are you sure they're stainless? What alloy?

[destroyer125]

They are stainless, Straight out of the manufactures box. I tried 8-18 stainless and 316 stainless. A few experiments I tried to etch with muratic acid, still nothing.

[f_sigona]

Hi Guys,

I am having simmilar problems to yours.
Did anyone manage to solve this issue. What type of surface prep are you using and are you etching in any acid and rinsing before the parts go into the blackening solution. Another question i have is are you using the blackening solution at full strength or diluted? Will this have any effect?

From experiments i have conducted on four identical components i have only got one to come out well so i am lacking consistency. Process was as follows:-

Degreasing
Rinsing
2 min dip in HCl 50% solution
Rinsing
2 min dip in Blackening solution
Rinsing
Drying
Heat in oven 250 deg C for 15 mins
Water quench

Any suggestions are welcome

Thanks.