Multicoated Glass Negative Carrier
One of the improvements I have made to my Beseler 4x5 enlarger is upgrading to a glass negative carrier. Using a glass negative carrier instead of a glassless carrier improves the flatness of the negative that is being enlarged, which can improve the sharpness of the resulting print. While improving print sharpness, using a glass negative carrier also introduces several new challenges to print quality:
- Dust spots
- Reflection from the glass in the negative carrier
Dust on Negative Carrier Glass The glass in the glass negative carrier offers several surfaces on which dust can accumulate. Responding to this challenge takes a little more time, but it is simple to remove the dust that accumulates on the negative carrier using conventional methods which you can read about on many photography forums on the Internet. One tip is to wear a hat while loading film into your glass negative carrier. One big source of "dust" in the darkroom is particles that come from the darkroom worker's hair and skin. I haven't tried it, but the OnePass roller has also been recommended to me as being useful for removing dust from glass negative carriers. Reflections on Glass Reflections from the glass in the negative carrier can be addressed by replacing the negative carrier glass with multicoated glass. I did this for my Beseler negative carrier and I wanted to pass along some of the things I learned along the way. There are several sources for multicoated glass. They include framing shops, and several Internet-based vendors. Apparently, Zeiss makes multicoated glass, but I do not have a source for that glass. I used some multicoated glass sold by the Glennview company. Take a look at the picture below. On the left you can see the Beseler glass negative carrier with the original glass. On the right you can see the multicoated glass supplied by Glennview. I used a digital camera to make both of these pictures. The camera was set on the same manual exposure for poth pictures. Clearly this is not a controlled test, but you can see a pretty dramatic difference in the intensity of light reflected from the overhead light source, and the multicoated glass definitely reflects less light, as expected. 
After I obtained the multicoated glass, there were also several challenges in getting it installed into the negative carrier. If you are going to do this upgrade yourself, consider how you will:
- Cut the glass
- Bevel the glass
Cutting the glass is no different than cutting non-multicoated glass, so any glass or framing shop should be equipped to do this job. Beveling the glass is another matter entirely. In Portland, OR most of the glass shops I called were not equipped to bevel the glass and told me that it was both time-consuming and expensive to have done. I chose a different approach which bypassed the need to bevel the glass edges by making my own mounting system to secure the glass to the negative carrier, but do be aware that if you decide to bevel your multicoated glass, it may be a bit of an undertaking. I'm pleased with the results of upgrading my negative carrier to multicoated glass, and I think it removes one more weak link in the image quality chain!