Anyone know of an effective long lasting way to blacken all thread……

[RaisedByWolves]

And plated fasteners?

I’m making a tie down set at 1/2 scale for my mini mill and would prefer the traditional black look.

All thread for the threaded bars and nickel (?) plated flange nuts are the pieces needing to be blackened.

The strap clamps, step blocks and T nuts are black from the heat treating process so that’s covered, but I would like everything to match.

Ideas?

 

[pontiac428]

Hot caustic niter is the best looking and toughest black that we can do in the shop. Small parts can be done on a coleman stove in the back yard, and the ingredients are cheap. Degrease, boil in nitre, then boil in water just like home anodizing or rust bluing. Sticking with small quantities and a little careful thought about safety are all that are required. Get stainless pots from goodwill, the lye and sodium nitrate (stump remover) from the hardware store. Steal the temp gauge from the kitchen, and you're in business.

All thread is usually zinc plated, so it won't blue. I make a distinction between all thread and precision threaded rod. All thread is for hanging sewer pipes and sprinklers in my mind. Threaded rod comes from McMaster with a clear description of the coating, or lack of. Also, nickel plated hardware won't blacken unless you are electroplating "black nickel" over it at home, which is doable, but is a chromate process, so the same disclaimer as above applies about reasonable caution, planning, and safety.

Your blackening options begin and end at Krylon with all those dissimilar metal coatings on the hardware. You'd be best served to buy plain steel.

 

[GeneT45]

Parkerizing excels at this sort of thing. Your biggest issue (regardless of whether you pick parkerizing or not) is going to be stripping off whatever horrible, cheap coating was applied at the factory.

GsT

Edit: not that it matters much, and perhaps things have changed, but stump remover has traditionally been potassium nitrate (and a lot of adjuncts). Perhaps .gov's fear of black powder has forced a change in formulation...

 

[pontiac428]

Parkerizing excels at this sort of thing. Your biggest issue (regardless of whether you pick parkerizing or not) is going to be stripping off whatever horrible, cheap coating was applied at the factory.

GsT

Edit: not that it matters much, and perhaps things have changed, but stump remover has traditionally been potassium nitrate (and a lot of adjuncts). Perhaps .gov's fear of black powder has forced a change in formulation...

You can use racemic mixtures of nitrates. I've seen ammonium nitrate specified, too. Nitre, melonite, tennifer, all similar processes with various nitrate salts. The sodium and potassium are spectator ions in these reactions.

For the amount of prep and the number of steps involved, nitre is a lot less work, with fewer tanks, mixtures, and apparatus than parkerizing, at least based on Brownell's reliable method. Neither method is really safer than the other. I do like a parkerized finish, though. Ospho is not a true parkerizing process, though it looks similar. Parkerizing requires moly in the solution, while ospho converts whatever moly is in the substrate.

 

[matthewsx]

Have you bought the pieces yet? You can order black all thread and fasteners from McMaster.

 

[Parlo]

High tensile threaded rod is usually black & better quality.

 

[GeneT45]

For the amount of prep and the number of steps involved, nitre is a lot less work, with fewer tanks, mixtures, and apparatus than parkerizing,

Disagree. There's little that's simpler than park. Heat your solution to 190* and soak until done (3-15 minutes). Way easier than bluing or anodizing. One tank, one step. Add oil and it's a superb and durable finish. (Okay, that's two steps...) Perhaps the solution is more complicated, but buying a bottle of the concentrate from Brownell's, Lauer, AGI, etc makes the complexity of that particular solution irrelevant.

Cold bluing might be 'easier' (I don't think so, but it's a judgement call), but we all know it's a garbage finish that wears like a coating of soot (don't we?). I do have a 'recipe' for using Oxpho-blue that's better than the provided instructions, but it's still not as good as a good, deep, conversion coating.

GsT

 

[pontiac428]

Disagree. There's little that's simpler than park. Heat your solution to 190* and soak until done (3-15 minutes). Way easier than bluing or anodizing. One tank, one step. Add oil and it's a superb and durable finish. (Okay, that's two steps...) Perhaps the solution is more complicated, but buying a bottle of the concentrate from Brownell's, Lauer, AGI, etc makes the complexity of that particular solution irrelevant.

Cold bluing might be 'easier' (I don't think so, but it's a judgement call), but we all know it's a garbage finish that wears like a coating of soot (don't we?). I do have a 'recipe' for using Oxpho-blue that's better than the provided instructions, but it's still not as good as a good, deep, conversion coating.

GsT

Depends, are you referring to one-step phosphate "parkerizing", or black manganese parkerizing? Not the same process.

 

[RaisedByWolves]

I think I might spring for the black oxide threaded rod....Eventually.

I made up some 3/8" all thread studs at work today as I found material that was heading for the scrap tub and those will do for now. I was hoping to just sandblast and treat them, but the rod from McMaster is only $14 for two foot, so next time I order Ill get that plus they have the black nuts and connectors also.

 

[benmychree]

I have don niter bluing/blackening according to the US Aromory process with a 50/50 mixture of sodium/potassium nitrate heated to about 600-650 deg F. items need not be excessively cleaned and should be lightly oiled before immersion in the molten salts, it takes only about 5 minuities for small items to form a very durable finish. I have posted this many times in more detail previously; this is the real thing, all other recipes are second to 3rd or 4th rate or beyond; the comparison to soot is a good simile.