Double coating VDB's - some thoughts
I'm printing 7x17 VDB's today, and am trying to do some double coating as Sandy King has suggested.
I am using 6ml of VDB solution for the first coating, which might be 1-ish ml too much. His suggestion was 6ml for a 12x20. The 6ml are going on very nice and even for the first coat. The second coat is where the problems begin.
The paper is warping pretty badly (Somerset hot press), and when I go to do the second coat, I am getting run marks and even some puddling going on.
I am considering using 4ml or so for the second coating to see if I can eliminate the puddling on the second coat.
I am letting the first coat air dry for 5-10 minutes, then force-drying it if it's not completely dry for the second coat.
EDIT: The double-coating produces a very rich deep DMax which is quite pleasing, so I am pretty commited to figuring this out. It seems to be worth it on my early tests.
You might consider taping the edges of the paper to a hard surface. Also, don't wait so long to put on the second coat. I find that in 2-3 minutes the first coating has dried enough to put on the second coat.
Originally Posted by Michael Slade
You might try a brush - there is a specific watercolor brush I bought that really doesn't soak up much of the fluid and coats a warped surface quite evenly.
My photos are always without all that distracting color ...
I'm still using my 2 1/2inch brush...seems I never bought that Richerson brush after all (still in the plans though...).
I had been taping down my paper to my Corian counter top, coating one piece, then removing it, taping down a new piece, etc...then coming back to the first ones and doing the second coating.
I'll try doing the first coating, waiting a bit for it to dry, then doing the second coating.
Thanks for the suggestions. We'll see how this goes.
While I've never made a VDB that large I sometimes print 8x10 on 11x14 Bienfang 360 marker paper which warps considerably when drying. I solved the problem largely by taping the paper tightly around the outside of a large Cibachrome processing tube. It dried much more evenly this way and though it didn't take it all out, it was a great improvement. I suspect a large diameter PVC pipe would work just as well.
You might also try flattening the coated paper using a drymount at very low heat. This might affect the emulsion, but perhaps not. Worth a try I would think.
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6ml is quite a bit. when I double coat for VDBs I use about that total. for my 717s I coat the first coat at about 3.5ml and then 2-2.5ml on the second coat. If Im single coating its about 4ml total. using a richeson 9010 water color brush.
just my thoughts.
maybe that's why I'm seeing bronzing on this last batch? I'm also seeing some weird mottling and some blotchy color shifts. Up until today the Somerset hot press that I've been using has been very nice, but now with the double coating, I'm wondering if the paper's not holding up as well?
The 5ml for the 7x17's still seemed a bit excessive...I'll try single coating at 4ml and see where that takes me.
Unfortunately I just got a commercial job that needs to be done before Christmas. I'll be shooting the rest of the week and won't get to print again for a while.
For a 7X17 print I use about 4ml for both coating. I also mask off the paper to leave a covering area of about 7 1/2 X 17 1/2.
However, much depends on the paper, as those that have little sizing, or that have lost the sizing in an acid pre-soak, will soak up two or three times more of the sensitizer than others.
Originally Posted by scootermm
Resurrecting this thread...
I'm doing some 12x20's today. Using Arches Platine, double coating on the smooth side. Gave the paper a 30 minute steam bath in the bathroom before coating. RH is hard to control here in the winter, it's raining today, could be dry as a bone tomorrow...you never know. I do also have a pot of boiling water where I am coating.
I have marked off an area 13.5 x 21.5 inches, using 6ml of solution. Coating with the Richeson 9010 brush.
I am thinking that 6ml is a bit much, and will coat the next sheets with 5ml. There seems to be some excess solution and a bit of puddling near the edges.
I'll let them dry, make some text exposures and report back.
Originally Posted by Michael Slade
If you have a small room where you can coat and dry then a humidifier would be a good investment for printing with iron sensitive processes. I picked up one for $45 at Hope Depot that will raise the humidity in a room about 10X14' by about 15-20%.
There is no right amount of solution per print area since this depends very much on the paper and its humidity. 6ml is about right for me with most papers when the RH is 55% of more. If there is puddling, just keep brushing until it evens out. Nothing wrong with that so long as the paper has a good size and you don't abrade it with the brush.