How to facilitate holders insertion on old Linhof?

[Paul Schilliger]

The spring back on my Tech 5x7 is pretty tight, which is good, but inserting the holders requires quite an effort. The aluminum is naked and starts being attacked. Would an epoxy paint be convenient to bring back a smooth and hard surface?

[David R Munson]

You might try rubbing a little paraffin or beeswax on the surfaces that contact the film holder when it's inserted. It might make things easy enough that you don't have to do anything else. I did this on my Linhof when I first got it and haven't had any trouble since.

[Paul Schilliger]

Dave, that's probably what I will do later, but right now the surface is so rough that I think it's in need some extensive care not to wear out too fast. Maybe a very hard paint coating ?

[David R Munson]

Ah, I misinterpreted, then. Maybe just take some fine carborundum paper on a sanding block and smooth it out that way? So long as the GG still seats properly, this shouldn't necessarily mess up your plane of focus. If you coat it with something, it seems like it would really have to be at least as hard as the metal it's coating over, as if its not then the same forces that roughened the metal would roughen the coating all the more quickly. Maybe taking it to a machine shop or somebody who works with metals a lot would be a good idea. There's got to be a good way to remedy this...

[Julio Fernandez]

Paul: The repair process will involve several steps. First, the pits on the metal must be filled, at least in areas exposed to friction; this can be done with a metal-filled epoxy. After filling, even the surface by sanding with wet carborundum paper, not too fine so that you leave a rough enough surface for adhesion to the paint. The next step is painting. What kind of paint will be the question. It should be a chemically reactive paint to provide maximum durability but also it should provide some slip. Candidates are epoxies, silicone-alkyds and urethanes or hybrids thereof. The silicone types will provide maximum slip. There may be other silicone based reactive paints as hybrids with epoxies or urethanes. All this stuff is industrial and will not be found in retail. Finally, after painting, -ideally by spray. There will need be a rub down or sanding of each coat for maxium smoothness. For the final coat, wet sanding with carborundum type papers of a very fine grit will give you a very smooth industrial finish. Hard urethanes and epoxies and hybrids thereof can be very tough, these are used in such things as coated metal in high wear areas and there is no reason why they they should not do what you want. Aluminum pits due to corrosion, the coatings will preserve the aluminum. Adhesion is key to get a great job, I would experiment with each step to ensure that you get good adhesion between the fill and the paints and between each paint layer. Reactive coatings can only be recoated within a short time span after which subsequent layers may not adhere. For any questions just drom me a line.

[Paul Schilliger]

David, Thanks! Julio, I just have to pull up my sleeves now and follow your steps! I'll check what product comes handy in a small package. Thanks a lot for the kind infos, you're the specialist! For instance my Toyo back is painted with the same paint as for the rest of the camera. The paint is just slightly scratched after years of use of the QuickLoad holder and the holder slips in place just like on a soapy surface. This was probably done with some sort of thermo-painting.