Hi al
Me and my students bought the deionised ossein originally for oil pigment
printing for which it works beautifully.
It's deionised quality was an unforeseen benefit. when we came to platinum
printing.
That quality is of no significance in gum printing. I use water straight from
the tap for gum size and development and the dilution of the dichromate.
I buy deionised water from the pharmacy round the corner or from the health food
shop on the corner by St Margarets station. Distilled water can be bought from
the filling station. At the local hyper-market the distilled water at the
filling sation is even cheaper.
Purified water such as distilled or deionised is essential in most metal
printing processes as the chlorine in tap water contaminates.
Until last year our water came from the chalk artesian basin under London. Now
it comes from the London ring main and it has changed the colour of my
cyanotypes. But the chalk no longer blocks up the darkroom sink when it is
precipitated by the HCl in platinum clearing baths and that is also because I do
not use HCl anymore.
What's VDB, a kind of speed ?
Terry