Pros : I used the metal nozzle (large size) on a bottle of white, drew designs on 20 black glass cabochons I had pre-fused and then fused them at the recommended temperature of 1500f or 815c, on a short nine and a half hours fusing schedule for a sc2 paragon kiln. Every one came out perfect and the ease of use meant I had very few mistakes. If I made a mistake it wiped away easily with a damp tissue. I drew swirls, leaves, dots, trees and they all look sensational.They have had bails attached and go into the local gallery tomorrow for sale. Black base with white glassline pen is superb and is also great with dichroic if drawn onto any black areas.It gives a matte finish on a shiny black background and stays as bright after firing as before and keeps its shape. Cabs to the back of the kiln fully fused and cabs to the front kept their slight relief above the surface.
Cons : The smaller metal tip I cannot manage to push any shading material through but the larger works a treat and is not too large for fine lines for jewelry.With the cap on give the bottle a vigorous shake, remove cap and screw on large tip. Point tip down, over tissue paper and gently squeeze until a small amount comes out. Wipe the tip on a tissue and your bottle is primed to go. A gentle squeeze is all that is needed for this to flow consistently. The metal needles clear any blockages if it dries in the tip.