Chemical blackening advice
- Thread starter jhockuk
- Start date
Steph Dale
Western Thunderer
James,
Getting the metal clean is certainly important. I give a good wash in meths.
There are two ways I frequently use to apply the blackening. One is to rub the surface over with a cotton bud wetted in the solution. The second is to dilute the solution and dunk the parts in the dilute solution.
Once the parts are blackened enough they should then be dropped in to cold fresh water.
Anything else is a refinement of this basic approach.
I hope that helps,
Steph
Getting the metal clean is certainly important. I give a good wash in meths.
There are two ways I frequently use to apply the blackening. One is to rub the surface over with a cotton bud wetted in the solution. The second is to dilute the solution and dunk the parts in the dilute solution.
Once the parts are blackened enough they should then be dropped in to cold fresh water.
Anything else is a refinement of this basic approach.
I hope that helps,
Steph
Dog Star
Western Thunderer
What Steph says above is the crucial part of the preparation. Meths or IPA are going to get rid of most of the soluble muck on the metal... you may benefit from mechanical cleaning once sweat, oil and grease have been removed.
Steph Dale
Western Thunderer
James,
'Nickel silver' is actually a bronze, so the same blackening as for brass will work; it works on the copper in the alloy.
I'm not certain but I think there is only limited differences between the chemicals involved for different copper alloys. If the blackening forms partly or too quickly, or flakes off, it's because the reaction is too fast; diluting and/or rubbing the surface of the metal can help.
For other metals the chemicals are different. Stainless steel and aluminium are the only common modelling materials that can be tricky because of their hard oxide layers, but even this depends on the alloy of the metal.
Steph
'Nickel silver' is actually a bronze, so the same blackening as for brass will work; it works on the copper in the alloy.
I'm not certain but I think there is only limited differences between the chemicals involved for different copper alloys. If the blackening forms partly or too quickly, or flakes off, it's because the reaction is too fast; diluting and/or rubbing the surface of the metal can help.
For other metals the chemicals are different. Stainless steel and aluminium are the only common modelling materials that can be tricky because of their hard oxide layers, but even this depends on the alloy of the metal.
Steph
Rob Pulham
Western Thunderer
As Steph says this is an added extra, but I have found that once washed with meths if you keep the steel warm as you apply the solution with a cotton bud it takes better with a smoother deeper finish - I use an old hairdryer to dry the meths off the wheels which kills two birds.....
I have only tried this on Slaters wheels which is why I said "keep the streel warm".
I have also tried the dilute and dunk method but found that the result was a bit patchy. This may be down to lack of mechanical cleaning having just dunked them in meths for a few minutes as I do when using a cotton bud to apply the blackening.
I have only tried this on Slaters wheels which is why I said "keep the streel warm".
I have also tried the dilute and dunk method but found that the result was a bit patchy. This may be down to lack of mechanical cleaning having just dunked them in meths for a few minutes as I do when using a cotton bud to apply the blackening.
Heather Kay
Western Thunderer
I used to be a cotton bud user, but now I use a superannuated sable paintbrush. I find it allows better control, especially getting into nooks and crannies.
The brush is used only for the chemical work. I don't bother to wash it out after use - read that as being lazy - and when it dies it will be replaced by another superannuated brush, cascaded from painting duties as the hairs become unruly!
The brush is used only for the chemical work. I don't bother to wash it out after use - read that as being lazy - and when it dies it will be replaced by another superannuated brush, cascaded from painting duties as the hairs become unruly!