Question regarding Greenwich Coupling

[B.Meldon]

As I mentioned they are also in unpainted brass.

The other changes would seem to be an improvement and has encouraged me to buy more, but coming only in bare metal will add at least one more step, which is going to be a nuisance.

From what i understand the blackening process is sadly no longer offered by etchers.
To get this done elsewhere, or change to another etcher would have been cost prohibitive.
In addition the black did, at times, tend to come off when bending the coupling into shape requiring painting, or at least touching up anyway.
Using a permanent black marker pen is a quick and easy alternative.

[JulienW]

As I mentioned they are also in unpainted brass.

The other changes would seem to be an improvement and has encouraged me to buy more, but coming only in bare metal will add at least one more step, which is going to be a nuisance.

From what i understand the blackening process is sadly no longer offered by etchers.
To get this done elsewhere, or change to another etcher would have been cost prohibitive.
In addition the black did, at times, tend to come off when bending the coupling into shape requiring painting, or at least touching up anyway.
Using a permanent black marker pen is a quick and easy alternative.

Equally dipping the built coupling into some brass blackening solution for a few seconds then rinsing off with water would be fairly quick...

[Graeme Dunbar]

Equally dipping the built coupling into some brass blackening solution for a few seconds then rinsing off with water would be fairly quick...

Do you have a recommendation for a brass blackening fluid please? There appear to be different brands or formulations and have different behaviours.

[Matthew Mawson]

Equally dipping the built coupling into some brass blackening solution for a few seconds then rinsing off with water would be fairly quick...

Do you have a recommendation for a brass blackening fluid please? There appear to be different brands or formulations and have different behaviours.

I've recently had success with Carr's Metal Black for Brass, used on some DG couplings. First I washed them in Isopropyl Alcohol (IPA) with a piece of paper towel, then decanted a bit of the metal black into a small glass container with enough to cover a coupling. I dropped one in, taking care not to touch it with my fingers and swished each coupling around for 30-60 seconds and it came out pretty good. When out it went straight into some fresh IPA for a wash and then left to dry. Depending on how much use it'll get I may give it a spray of varnish so the blackened surface doesn't wear off.
Hope this helps :)

[JulienW]

One of the best ones I had was one I made myself.

This used copper carbonate mixed in a 1:1 weigh to volume ratio with 0.880 SG Ammonia solution. It's rather pungent (eye watering!) so when I made it I did so in a fume cupboard. It was less stinky in use though, but you wouldn't want to leave the pot open for too long!

I still have a jar of copper carbonate, but haven't tried to get any of the ammonia (I suspect this might not be too easy) and I don't have access to a fume cupboard, so it's unlikely I'll be making any more.

Failing that the Carrs Metalblack for Brass has worked well for me, as has Hobby Holidays' Chemical Blackening. They probably need a little practice to get the right amount of time dipped in the solution - too much and the coating will flake off - before you wash off the solution with water.

You may need to degrease the couplings (dip in alcohol, acetone or butanone or similar for example - allow it to evaporate and try not to touch the couplings once dry) before you dip them in the metal black to get the best from these solutions.

Hope that helps...