“I'll have to keep my eyes out for a vacuum frame, there are a few camera/photo markets coming up in the fall, maybe something will be there.”
This is not something I would expect to find at camera/photo markets. This came from a company that salvages used printing equipment from print shops that have either gone digital or gone out of business.
I would search here and on the LF Forum for vacuum frames. This subject has come up before. I have seen links to articles on how to build one. The plate maker I mentioned includes both a vacuum frame and a 1200 watt mercury vapor light. This would make it a very useable device for at least the alt processes I have done; Platinum, Van Dyke and Cyanotype. Please research further as I profess little expertise. I plan to start using it next month. I have used UV light sources and spring loaded print frames prior to this.
“On the vacuum idea, not sure of the space required, I've never seen one. How big are these?”
I mentioned my vacuum frame was 25”x29”, probably the minimum size for your planned 20”x24” negative. The vacuum frame base is 7” high. There really is very little to this, a glass top, a rubber blanket and a pump to pull out the air. Many have remote pumps to remove the noise to another room. On the Amergraph, the frame for the over head light takes up space. The whole device is 31” wide, 28” deep and 31” high.
“If big I may have some serious spouse approval factor issues.”
This is a second marriage for both of us. Both our first spouses went off with other people. After retiring I took a few university photo courses. I wanted a home darkroom. My wife had smelled the fixer on the floors of dirty, 15 enlarger school darkrooms and said not in my/our house. I explained about cleaning up after each use, exhaust fans and got nowhere. Finally I looked at her, said this was really important to me and quoted the old saying, “The man who has a hobby at home, tends to stay at home.” She thought for a minute and said, “How much space do we need?”
That was seven years ago. We just celebrated our 19th anniversary.