Hi Christof,
There is a shoe ink in Portugal that is used to paint shoes and also works pretty well in celluloid material. Painting celluloid is actually one of the indications of use in the instructions leaflet. It is called Faisca Galgo. I have used it with great results.
It should be applied to the interior of the barrel and will work very well. It will not be perfect because it is hard to replicate that shiny finish the exterior of a NOS Black barrel has. But it is a close match in black celluloid pens.
I also tried to use a mixture of black celluloid dissolved in acetone until you have a type of low viscosity black gel liquid to paint the exterior and had mixed results. It works but its very prone to create small air bubbles when applied into big surfaces like a full barrel and so the exterior can be ruined, but when it works it is just perfect as the external paint used by MB in the 14X series for instance.
The main challenge there will be to put a cork/ gasket or an oring or similar to isolate the transparent part of the barrel from the part to be painted and then fill part to be painted. I use a small needle or a paint brush to cover with ink the internal part to be painted of the barrel and also use needle gaskets or the actual gasket of the pen to isolate the "to be painted" area.
Don't use to much ink and drain the excess ink after applying it to prevent deformation of the celluloid due to the solvent used on the ink. Apply more than once if the pen is not as black as you like. Test first in a another barrel so you are comfortable with the use.
Please send me you address back channel and I´ll send you a bottle of Faisca Galgo Black tomorrow so you can test it.
Best regards
Vasco
Edited by piscov, 01 May 2014 - 02:14 PM.
