Hand pump for vacuum frame?

[Rolleiflexible]

I just bought a beautiful 16x20 vacuum frame, and a small motor-driven pump for the suction. Now that I am looking at it, I wonder whether anyone has ever used a manual, hand-held pump for the vacuum. The amount of air to be evacuated is tiny -- it seems like the motor pump is overkill for the purpose.

My exposure times are under 30 seconds. I can see how a long exposure time would not be practical, but for periods of less than a minute, can handheld pumps do the job? If so, any recommendations for models and sources?

 

[bdial]

An automotive vacuum brake bleeder might work. For example; https://www.skf.com/mityvac/products/hand-vacuum-pressure-pumps/hand-pump-kits/mv8020

The mityvac is pretty much the original, there are a lot of similar ones in the market, including some that are bigger. The one I linked might struggle a bit to draw enough air from a 16x20 frame.

 

[beemermark]

Back in the day I used my vacuum cleaner. Is there some reason you do not want to use the supplied vacuum pump motor? Paper is porous, you need to maintain a vacuum while you're focusing, etc.

 

[Nicholas Lindan]

Vacuum frames are designed for use in pre-press contacting applications were very tight contact is needed, usually between two films or a film and a lithography plate (the sort that is used in an offset printing press). The frame is pumped down to 14" of vacuum and the vacuum is held there for ~30 seconds unless you have a nuVac or other 'fast-draw' system. In their intended application the problem is that air trapped between two sheets of impermeable material has to diffuse out between the sheets - a bubble of air has no reason to move and can sit there being recalcitrant for a long while.

If you are contacting a negative to a porous medium, like photographic paper or Pt/Pd paper, then the pump-down is easier and faster. Also for contacting to a photographic print the register doesn't have to be all that precise.

So you may be able to use a small hand vacuum pump without problems.

If I may ask, what is the problem with using the vacuum pump that came with the frame?

* * *​

Vacuum cleaner style pumps are used with vacuum easels and vacuum camera backs. They don't supply enough vacuum for a vacuum frame.

 

[Rolleiflexible]

If I may ask, what is the problem with using the vacuum pump that came with the frame?

None! It just seems like overkill and I like to simplify where possible.

Thanks, all, for the replies. I am grateful for the insights.

 

[beemermark]

Back when I had a dark room and a 4x5 enlarger I used the vacuum frame to hold the paper down flat. I don't think you can find a normal print easel for 16x20 and larger.

 

[Nicholas Lindan]

There is a distinction between a vacuum frame and a vacuum easel - sometimes the terms are used interchangeably, leading to a small amount of confusion.

A vacuum frame consists of framed glass that hinges up over a gasketed rubber blanket. There is a hole in a corner of the blanket that attaches to a hose leading to a vane (Gast style) vacuum pump. A vacuum frame exerts 14 pounds/sq. inch of clamping force - about a ton per square foot. With the high clamping force and a vacuum between the exposed material the films are held in extremely intimate contact. There is no danger of breaking the glass with thicker materials, unlike a contact printing frame.

A vacuum easel is a shallow box with holes drilled in its upper surface every 1/2 inch or so. The box is attached to a vacuum cleaner type pump. The easel holds the paper flat with about 1-2 pounds/sq inch - which is plenty to hold film or paper flat. Vacuum easels are also used to hold the film in process cameras.

 

[choiliefan]

The small pump from a food vacuum sealer would probably work. Some have an additional port for small tubing. I see these at thrift stores all the time, usually with broken lock-down tabs but functional pumps.