Digital BW, The Print

Hi Paul,

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Paul Roark"
<paul.roark@v...> wrote:
> Unfortunately, yellowing has plagued the coatings and lacquers 
> historically. That's one reason I'm very reluctant to use something 
> that does not have either a good Wilhelm test or other evidence or 
> reputation for non-yellowing.

Yes. Certain varnish and lacquer do have reputation for yellowing.
Using the acrylic polymer alone (such as Golden GAC 500 or 700)
increases color depth but not as much as a top coat of resin based
varnish which also adds strength.

I'm experimenting with Krylon Matte Finish which dulls the shiny top
coat without significant reduction in color depth.

> Nick, what airbrush system did you find worked best? A Premier 
> Imaging contact says they've found a CO2 cartridge powered sprayer
> that works well, but I have not been able to get a product name
> from them.

I use an Iwata HP-BCS airbrush with a relatively weak Iwata Studio
Series Sprintjet. It does a good job for the initial water-based
sealing of the media. Within 15 minutes I can use the foam brayer to
apply the same liquid at a much faster rate. I don't remember exactly
how much I paid for it but it was a good deal when the package was on
sale at a local art supply store, for maybe about $175 for both the
compressor and the airbrush.

After finish using the airbrush I just remove the bottle and spray
with the water faucet running into its inlet to flush it. There is
virtually no cleaning afterward. Every 3 months or so, depending on
how much use, when the flow becomes rather restricted, I just use a
needle to clean out built up acrylic and it works like new again.

Badger makes a cheap CO2 spray assembly for about $25. I think you can
get it at dickblick.com. The compressed air can get depleted so
quickly though.

> Getting a fine spray with reasonable coverage seems to be one of
> the tricks with water-based coatings.  I tried the Preval, but it 
> didn't work.  The local paint expert is now a fan of Crown's aerosol 
> "Spra-tool" (Aervoe Industries) for small jobs (and cheap people 
> like me).  I'll give one of these a try this week, hopefully.  It 
> has different nozzles and more higher pressure than most systems.  
> We'll see.

The trick is in proper dilution of the liquid to be dispensed. You
need to add airbrush medium or transparent extender for spraying. This
is alot easier and safer than any darkroom mixing.

I think the Spra-tool should work just fine if you prepare your
solution properly. And replace the compressed air tank when the spray
gets kind of thin.

--nick