Blotchy Blackening

[peter6172]

That was JAX Copper Blackening solution I had these huge problems with. I now threw this crap away and use Birchwood Casey with success.

I have used both Birchwood and Jax products. The ones intended for brass are both chemically the same so the results shouldn't vary. The only difference will be the strength of the chemical. I find JAX very quick to react compared to Birchwoods so it's obviously a stronger solution.

The mount of time you metal stays in the solution greatly affects the end result.: stay in too long and a crust forms which will fall off. As soon as the metal starts to turn black it's time to remove it and wash thoroughly in clean water.

Note 1: Chemical blackening only adds a patina coating to the metal, it does not change the colour of the metal.....

I Brush first with a fibreglass brush, soak in Isopropyl Alcohol, remove and dry, then put in the blackening solution. From the blackening solution to water for thorough rinsing then onto paper towel to dry.

Note 2: If you are soldering brass/copper parts not all solders will blacken using the brass blackening solution. This is likely due residual flux (particularly if using electrical flux cored solder) but sometimes because the makeup of the soft solder is not compatible with the blackening solution.

 

[Don Case]

Like I said earlier, I'm using Birchwood Casey "Super Blue". I just noticed it says right on the bottle that it will not blue non ferrous metals but it seems to work great on copper. I wonder why they say it won't work?

 

[peter6172]

Like I said earlier, I'm using Birchwood Casey "Super Blue". I just noticed it says right on the bottle that it will not blue non ferrous metals but it seems to work great on copper. I wonder why they say it won't work?

It may, but they won't guarantee it to do so....

 

[Stuart Little]

A lot of brass wire is coated for the jewellery crafts. When I buy brass wire I go for 'uncoated', a quick clean with a fibre glass pen or IPA (not beer), dip in Birchwood Casey, & 'hey presto'!

 

[bill36]

Thanks. When I was writing my post it occurred to me that a quick test was in order. I cut a little piece of wire and heated half of it, then cleaned and blackened as usual. I got this

View attachment 348766
The blackening took beautifully on the heated side and not at all on the other side. I did a very short blackening treatment. So next I did it again but instead of heating half I cleaned it with acetone. It didn't help at all, the wire didn't blacken anywhere(no picture, imagine a pristine piece of wire )
So you must be right, there must be some kind of coating put on the wire. I guess I'm going to have to heat the wire before I try to blacken it. It doesn't need much heating, barely enough to start to discolor the metal. Bit of a nuisance but it really makes a difference in the blackening.

Great experiment. I will be trying it myself.

 

[stuglo]

All done. these are the chains for the main shrouds. Not a hint of copper in the bunch. I'm chuffed. I've been chasing that blotchiness for months. Got it now . There are some coppery looking lines in the picture but they are shadows. Thanks for the help. Sometimes just the act of posting something triggers a thought.

View attachment 348783

Thanks for sharing. I've had this problem, now thanks to you, I have the solution.

 

[Don Case]

Very pleased to have helped. I follow your build closely. I also discovered that for the little spots that chip off while bending or spots of solder that don't want to blacken that a black acrylic Posca pen will touch them up quite nicely.