I have always used picture frame float glass for use in wet plate. I have never seen any problems related to the glass, other than pieces I have discarded because of scratches. I've made quite a few 30x40 prints from my half-plate negatives. I don't see why this glass couldn't be used for dry-plate. Thickness seems to vary by manufacturer. I've come across some pretty thin glass. I suppose the glass I'm using could have imperfections that I just am not noticing but if so they are minute in comparison to the imperfections that can come up using the collodion process.
Bob Szabo At 11:00 AM 6/3/02 +0800, you wrote: >At 2002/5/31 20:59:00, you wrote: > >Hi > > > >I have been put onto by Mike Ware, who says you may be able to help me. I am > >trying to research recipes for dry plate glass negatives. I have found it > >very hard to locate information of what ingredients are used and how to > >apply and develop the emulsion. Mike said that this thing is really your > >area so I'm hoping you may be able to help me in some way or another. > > > >Regards > >David Bolwell > > >Hi, David-- > >Your inquiry caught my eye, because I have been exploring the Internet to >see what the state >of glass-plate manufacturing might be. Except for specialized plates for >scientific applications, >there seemed to nothing. I was particularly interested in the fate of the >users of one-shot >color cameras like the Devin, which were designed to take only plates >loaded in special >registering holders. > >I have _Photographic Emulsion Techniques_ by T. Thorne Baker (Boston, >1941) which I am >sure contains almost all the information you need. Although it covers >commercial production, >Chapter III should be of particular interest to you. Here is a list of >what it covers: > > III. Laboratory Equipment > Layout for Experimental Work -- Commercial Production and Its > Requirements -- > Ventilation -- Safelights -- Digesting Apparatus -- > Thermostatic Control -- Washing > and Filtering of Emulsions -- Making up -- Cold Storage > >I have no idea whether there is anyone still around that could claim >copyright, but I hesitate >to offer to scan its 187 pages. Perhaps if you could narrow down the >requirements of the plates >you want to make, I could furnish you the information on an as needed basis. > >I have used dry plates (up to 11x14 in.) but on one occasion I even made >some 2x2 in. lantern >slides. If you are working with unsensitized or orthochromatic emulsions, >the critical coating >process can be done under a safelight. If you want to coat panchromatic >emulsions of any >appreciable speed, a mechanical coating device is essential, and I know of >no off-the-shelf >small-scale devices. > >However, there is an alternative. When panchromatic sensitization first >appeared, >manufactured panchromatic plates were not always readily available, or >they were dear and >beyond the budgets of some users. It is possible to sensitize a >blue-sensitive emulsion to the >red and green portions of the spectrum by immersing it in a solution of >the sensitizing dye, >draining it, and drying it, all of which can be done in complete darkness. > >A critical part of this whole process is the selection of the glass. It is >_not_ advisable to >reclaim old glass plates, at least if they have a developed image. The >silver seems to be >absorbed or adsorbed by the glass, leaving sites that will cause a >subsequent image to appear in > subsequent development. > >Ordinary window glass, unless glass manufacturing methods have improved >considerable, >possesses striations which are going to disturb the uniformity of light >distribution, certainly >during enlargement. The common glass manufacturing process used rollers to >draw the >molten glass out of the vessel in a continuous process, with no guarantee >of uniformity of >thickness or absence of internal strains. To produce glass of a higher >quality (plate glass) large >slabs of glass of a lower grade were polished using huge surfacing wheels, >much like lens >grinding. > >I have heard more recently of a clever technique which uses a large vessel >of molten tin. The >molten glass is poured on it, where it has a chance to flow out into a >uniform thickness before >it is drawn off and cooled. This could be for more than academic interest >to you if such glass >is produced in thicknesses of 2 mm or so. This would give you glass of the >flatness that you >need and still fit into a plate holder. I'm sure in the vast area of glass >manufacturing there will >be sources for what you need, which at least in the past was usually >referred to in the literature >as `B' glass. (By the way, Kodak once offered 20x24 in. plates on highly >finished glass, 0.25 in. >in thickness.) > >But I could rattle on at even more tiresome length. I can be or more help >as you narrow your >field of inquiry. > >George Arndt > > >_______________________________________________ >Cameramakers mailing list >[EMAIL PROTECTED] >http://rmp.opusis.com/mailman/listinfo/cameramakers _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
