brass black

[VitusBering]

I just used Birchwood Casey Brass Black on a test batch of tiny brass parts (leftover stanchions, fittings, etc.) and I am very pleased with the result.

It was my first time blackening and it worked out really well. 50/50 mix of blackener and distilled water after cleaning the parts with IPA. In both cases, I shook up the container really well. I rinsed in distilled water and left the parts to dry on a lint-free shop towel.

[Roger Pellett]

Way back when, AJ Fisher, the Rolls Royce of Model ship fittings offered many of their brass items with an “oxidized finish.”  This was a tight black matt finish.  I have some of these fittings that are 80 years old.  The finish is like new.  I have no idea what it is.

 

Roger

[Dr PR]

I have asked several times if blackening compounds will blacken solder - with no answers. So I decided to experiment to see how well it works.

 

I have been soldering since I was a kid, and I like working with brass. On my current build I will need a lot of eye bolts and ring bolts. I can bend the brass wires into shape, and they will hold against light forces, but thin threads can slip through the gap. I prefer to solder the gap in the ring, as much for aesthetic purposes as to increase the strength.

 

Up to now I have been painting the brass fittings with flat black enamel, but this is easily chipped when handling the parts. And the paint does add significant thickness to small parts. So I wanted to try blackening the metal to see if that gave a more durable finish.

 

Here is a photo of some eye bolts with soldered gaps. The wire is soft brass, 0.025" (0.635 mm) diameter, and the hole is 0.035" (0.889 mm) diameter. This is a good size to work with Syren's new 4 mm plastic hooks.

 

 

I used a liquid water soluble flux, and the solder was tin/lead 60:40 with a resin core flux. After soldering there was some flux residue. First I washed in water to remove the water soluble flux. Then I washed in acetone to remove the resin flux and grease. It only takes 10-20 seconds for the flux to dissolve completely.

 

Next I placed the parts in Birchwood Casey Brass Black diluted 50:50 with water. I let it stand 10 minutes, at 67F (19C) stirring occasionally, and then washed with several water rinses.

 

 

 

You can see from the photo that the solder blackened just as much as did the brass wire. Hooray! This was very important to me because there is a lot of solder smear over the wire and I don't want this shiny silvery surface to show.

 

 

But is the blackening just a thin film on the solder, or is it actually blackened metal? The photo shows some pieces straight out of the blackening solution (after drying) on one side and some that have been rubbed with soft cotton on the other side. Which is which?

 

Those on the left have been polished, and the parts on the right have not. A small amount of the black did rub off of all the pieces onto the cloth as others have reported. However, the blackening didn't rub off the solder any more than from the brass!

 

 

 

For small parts like these eye bolts the process I used is adequate. But you can see some bare spots, perhaps from flaking. The pieces turned dark almost immediately after I placed them in the blackening solution. However, it seemed the solder took longer to darken than the brass. Perhaps five minutes in the solution would be enough?

 

For larger surfaces it might be a good idea to etch the brass with Sparex before blackening to get a more uniform finish and avoid flaking.

Edited July 15, 2023 by Dr PR