Re: brush vs tray size for gum
Jack, I use a 1"-12, 1/2" diameter rod for coating paper for carbon final support. This leaves a wet coat height of about 0.4mm. Before coating the rod is placed in a tube with hot water at about 130ºF. I spread the gelatin solution over the paper, usually about 22"X29", and quickly even the solution by hand or with a brush. Then, I roll the rod over the paper. As the hot rod passes over the surface of the paper it levels the gelatin coating, and at the same time, dissipates bubbles. I add the hardener to the paper just before coating, as Kerik described. The solid metal rod holds heat much longer than glass, either tubes or solid, and is much more effective for my use. I suspect the same would be true for coating papers for gum printing. Sandy King At 4:53 PM -0400 10/2/06, Jack Brubaker wrote: Sandy, What size rod and what thread do you use? JackFrom: Sandy King <sanking@clemson.edu> Reply-To: alt-photo-process-l@usask.ca Date: Tue, 26 Sep 2006 17:42:26 -0400 To: alt-photo-process-l@usask.ca Subject: RE: brush vs tray size for gum I also size papers for gum using 3-5% solutions and adding just a bit of Formaldehyde to the solution just before coating. I used to use a brush, but this caused a lot of bubbles. I switched to a threaded rod, which I heat before running it over the solution, and this completely eliminates the bubble problem because the warm rod dissipates the bubbles on contact. This is a technique that I adopted from coating carbon tissue. I am using more solution per given paper area than would be required for gum printing, but I think this should not matter in practice. SandyCarmen, The largest print I've sized is 20x24. But, if I was going to do 22x30, I would make a 22" glass coating rod and apply the sizing with the rod, then use a brush to fix any areas that were either too thin or too thick. This makes the process go very quickly so the gelatin doesn't have the chance to harden. I would also use formaledehyde rather than glyoxal to prevent yellowing. When using a glass rod, first place a towel on the table underneath the paper. This will greatly help keep the rod in good contact with the paper, especially for larger prints. I would guess about 30 ml of 3% gelatin with 18 drops of hardener would do it. Kerik www.kerik.com Original Message: ----------------- From: Carmen Lizardo carmenlizardo@yahoo.com Date: Tue, 26 Sep 2006 12:51:12 -0700 (PDT) To: kerik@kerik.com, alt-photo-process-l@usask.ca Subject: RE: brush vs tray size for gum Dear Chris and Kerik, I would love to brush size my paper, specially because use a full sheet of 22x30 inches when I print, and you could only imaging how long that takes and how much gelatin I need, but I can't seem to be able to get an even coat, and mixing glyoxal and gelatin together is out because I have to able to rise it off the gelatin to prevent yellow stains. Of course when I used Glut, it was from black magic and that did not work. I also felt it in ky eyes and throat and i not even the sensitive type. I am willing to try again, maybe with a different glut?? Any pointers that you can give me with the brushing?? I was thinking that it had to do with the size of my paper. The gelatin gets hard before I have time to cover the whole 22x30 sheet. Thank you kindly, Carmen --- "kerik@kerik.com" <kerik@kerik.com> wrote:Chris, I agree that tray sizing is a lot of mess and hassle for no substantial benefit. Plus, why do the sizing in 2 steps when it can be done in one? I use either a glass rod (puddle pusher) and/or a>>> brush. I add the hardener(formaldehyde in my case) to the sizing just before sizing each print. Three drops of formaldehyde and 5 ml of 3% sizing easily does an 8x10 to>>> 11x14 print. In these tiny amounts, exposure toformaldehyde (or whatever hardener one uses) is minimal. I get very even sizing this way. A little bit of curl to the paper, but nothing that causes any problems. I tried B.M. glut and did not like the results. It resulted in slower development and considerably more staining than with formaldehyde. As for sizing with unhardened gelatin, that sounds like another in a long line of T King's erroneous hyperboles. Speaking of gum, I taught a gumover workshop in Philladelphia this past weekend for www.projectbasho.org. On sunday it was 80 degrees F and 82% humidity in the darkroom. That's the first time I've printed gum in sauna-like conditions and it created some hassles with very slow development and the need to intervene with some brute force measures (brushes, fingernails, sandpaper). Anybody have similar problems printing gum in high humidity? The conditions seemed to cause problems with the sizing in particular because development was much closer to normal when I did a single coat of gum on unsized paper right out of the plastic bag. I'm speculating that the humidity either prevented the gelatin from hardening completely or it allowed the gum solution to soak into the sizing a bit rather than sitting on top. Despite the problems, I believe a good time was had by all. Although I always want things to go smoothly during the workshops, it's good for the students to learn how to deal with problems when they come up. Kerik www.kerik.com Original Message: ----------------- From: Christina Z. Anderson zphoto@montana.net Date: Tue, 26 Sep 2006 08:08:22 -0600 To: alt-photo-process-L@usask.ca Subject: brush vs tray size for gum Hi All, This weekend was time for sizing paper, and since I was doing small sizes (11x14's) I decided to tray size instead of brush size to see if it had any added benefits to brush sizing. I was sizing with gelatin glutaraldehyde as usual. I did use a piece of it right away, same day, and had no problem with the sizing not being hardened and producing "magenta squares" as did Carmen. However, I was using glut that I bought from a medical supply house (now available at the Photographer's Formulary) and not Black Magic. The gelatin on my paper was not slimy in any way so I know it was hardened. I am still not sure why Carmen got that problem, and am wondering about the suitability of Black Magic, therefore, with its added sulfite. It sounds like the same result I had when I tried Terry King's advice to use unhardened gelatin and got black squares. With tray sizing and cautions with glut, I gelatin sized the paper first, and then the next day I soaked the sized paper OUTSIDE in a tray of 50ml glut to a gallon of water. That worked well, but I would only tray size if the hardening part could be done outside to minimize fumes produced by the surface area of a whole tray of hardener, whatever type--glut, gly, formaldehyde. (When I brush size I keep the solution capped inside a thermos and pour out a cup at once.) The gelatin paper went in "slimy" feeling, and went out unslimy. The paper works fine but I learned a couple things: paper tray sized with gelatin will sink to the bottom, not float as does brush sized paper (except Arches) so if I am going to leave the paper soaking for a while it needs to be face up. I learned that the hard way. Back to floaters and sinkers, Mark. The paper does curl less than brush sized, but it>>> doesn't seem worth theadded trouble of trays. This is the only benefit I can see. Oh, maybe more evenness of sizing? I don't know this one yet...will have to print all papers.>>>My husband set up an ingenious "clothesline" for me--a rung ladder on its side has plenty of hanger-ready rungs. I learned another thing the hard way: I printed 4 prints on the unsized but shrunk paper with a cyanotype layer, put the paper through the hot gelatin sizing process and didn't THINK that the 140-whatever degree gelatin would shrink the paper even more and make registration a B---H but you bet it did--warped and shrunk. Luckily only 4 prints ruined. DUH. Or, as Clay says, DOH. The bottom line is that brush sizing is sooo much easier and works well and uses way less gelatin--I sized 24 11x14s with a a liter of 3%, and normally I can do that many 16x20s with the same. I don't think even with small sizes I would tray size... That's all my truly exciting weekend experience! Chris CZAphotography.com--------------------------------------------------------------------mail2web - Check your email from the web at http://mail2web.com/ .__________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .
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