While doing allot of reflection on all the possible variables involved with boosting Dmax I did notice the usage of PVA in the sensitiser. Is Liquitex PVA? The artist gloss medium to be exact. I saw that in the second editin of Dick Arentz's book as well as in a paper that Phil Davis sent me (in fact Phil stated he used a diluted formula to Size the paper adjunct to the addition of it to the emulsion itself). I am considering switching clearing agents as well for fear I may be getting a slight bleaching as well. I will try a 1% Oxalic acid as well as Perma Wash ala Jorge. This has been really informative for me and gives me a renewed sense of appreciation for the work Sean has put into this site. VIVA LA APUG!
Assuming PVA means polyvinyl alcohol, that's the working ingredient in modern white glues like Elmer's and "tacky" craft glues. I don't think it's the same as gloss acrylic medium, because PVA is white in solution and dries only semi-clear; a painting medium needs to be colorless and transparent, both wet and dry. I *think* Liquitex is a water based acrylic similar to Future acrylic floor "wax", and to the "ModPodge" decoupage kits from the 70s; it's the same as the dispersant in acrylic artist colors, but without pigment.
Originally Posted by mikepry
Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.
Okay, I haven't been doing this for very long so forgive me if I'm wrong.
Originally Posted by nze
I have used gold in one of my ziatypes on COT paper and I didn't see any purple coloration. Gold isn't unstable. According to the Sullivan book, the purple coloration in a ziatype containing gold is supposed to arise from when you're using a mixture where gold is 80% of the metal drop count in your mixture. I suspect that due to your multi-coat technique, you are introducing too much gold into your print, hence the purple color. (Incidentally, I'd love to make one of these purple prints sometime, it sounds like it would look cool!)
Perhaps if you only used gold in your final coat instead of all three, you could use it? Or you could reduce the drop count in each solution to prevent you from introducing so much gold into the print? Just my $0.02 worth.
There's two PVA out there that are used in the realm of alt photo. One is polyvinyl alcohol and the other is polyvinyl acetate. I'm talking about the alcohol, not the acetate. I haven't tried the acetate, except in gum printing. It may work out similarly.
The alcohol is a clear, fairly thick liquid that dries clear, and can be used to thicken the coating solution so it does not soak into the paper as far. Keeping the solution on the surface can increase the dmax a bit, but I didn't like the shift in color that I saw with the use of the PVA, so I don't use it.
That's all academic anyway, unless you subscribe to the belief that the dmax of the print must be 2.35 for the print to be a 'good' print. About 1.3 is all that is required to achieve a convincing black, and while a 1.5 dmax does look better in comparison, taken on it's own merits, a print with 1.35 or so will be percieved as a 'full range' print.
Originally Posted by colrehogan
in fact I also try to add the gold in the lats coating with a lithium feric salt which help to avoid gold stain. But there are free ferric salt which react with gold.
for the purple print I made some of them , blue , pink or purple you just need a low Drange negative as these mixture are quite contrasty. you should also work in a 50% Rh as if there is to much humidity the print will turn neutrel cold.
As for your question on BS forum. I try to add gold and platinum to ziatype, it sometimes works and others not. the more gold I use the less it works.
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This thread sure has enlightened me and this fine tuning has been a real learning experience as well. I'm not falling into the testing vortex, although as sick as it sounds I thoroughly enjoy it. I merely want to get the most out of my materials and make the finest print that I'm capable of making. Having said that here are some things that I stumbled onto along the way....
Started with a printing time of ten minutes under a 400watt metal halide and with one coat could get steps 20 and 21 to merge. Weak Dmax though.
Double coated with 1st coat diluted as discussed and double coated with two full coats and...no difference, but the steps 20 and 21 did not merge???
I assumed that more emulsion would naturally bring printing times down. Not the case. I needed 15min to merge the steps. Now I wonder if I am experiencing solarazation?
Found the coating rod to be substandard and I still maintain that the white fuzzy hairs of the paper taint the densitometers reading. I happened to be in Downtown Chicago on business today and went into Pearl Art and bought a 2" magic brush to compliment the 3" I ordered online (Wow, what a store). I really think that will keep the paper abrasions down.
And Michael M - I'm happy with the 1.42 and will work with that. Your last response was comforting. It is a substantial improvement to what I had and will tweek little things here and there along the way. With all the little variables that come into play here I can say they are nothing compared to the 2 years I spent in an albumen haze...ee gads, talk about a loose cannon!
Per your question on the speed of printing...
As you increse the amount of sensitized solution in the paper (think of it as a density issue, ml of solution per square inch of paper), you will slow down the printing speed of the coated paper.
This is easily testable by coating a small sheet with a very thin coat, and another with a normal single coat, and another with a double coat. The thinnest coat will be the fastest, and the heavier coats will print slower.
So the results will be the opposite of what you were expecting.
This is also a reason that the borders of prints will often solarize when printing palladium, because the borders may not have anywhere near the concentration of coating solution as the main part of the print area.
An extreme case of this speed difference is in conditions where the print was brush coated, and there may be some little wisps of brush marks beyond the edge of the primary coated area. If they are very thin wisps, the speed will be so great that they may fog even when covered with rubylith or goldenrod paper.
FWIW.....I realize that I'm probobly preaching to the choir here but as far as the Richeson brush goes....very nice. Really nice. I fought it for a while but decided to give it a try and it's really amazing. I noticed a HUGE difference in the smoothness of the tones in the printed test wedge. Hardly any of those annoying fuzzy white hairs like I was experiencing with the rod. Thanks again!
Which brush(es) did you get and where did you get them?
Jerry's Artarama has the Richeson 9010 for very good prices.
You will probably want a 1-1/2" for up to an 8x10 image. As you go bigger, you'll want a larger brush.
Like you, I resisted getting one because of the relatively high cost of the brushes. Now, I wouldn't consider using anything else. Keep them clean and treat them well, and they will last a long time. I stripped the laquer off the handles of mine, and then sealed the wood with waterlox because the paint on the handles will eventually start to crack, and it may foul a print with a flake.
If you haven't seen a description for how to use the brush, this is one brush you use WET. Dip it into distilled water and get it soaked. Pull it out and shake it four times onto the floor pretty hard. It should appear totally soaked and the bristles should be stuck together, but not dripping at all.
It'll take a little practice to get the right amount of H2O in the brush. Too little, and it'll soak up solution, too much, and it'll deposit H2O onto the paper as you spread the solution around. Just right, and it'll neither absorb or leave behind any water.
When it's just right, you will notice that when you wash it out, almost no discoloration occurs in the wash water.