Another homebrew ground glass method

[CR Roberts]

The subject of homemade ground glasses is certainly not new. Much has been written on the topic and some very valuable and informative presentations have been made. Unfortunately, circumstances did not allow me to follow any of this great advice when I broke my ground glass last evening. I plan to use the camera today and needed a quick but decent replacement with no time to order grinding grits.

So, with one dollar I obtained a 4 x 5 piece of window glass from my neighborhood hardware store and another couple of bucks bought me a 3-sheet packet of Norton "3X" 180 grit aluminum oxide sandpaper. I washed the glass thoroughly, covered the intended clear side with masking tape, donned a pair of latex (actually, latex-free) gloves, pulled a dust mask over my proboscis. laid the sandpaper on my clean workbench and began scrubbing the glass over it in a random pattern. After every hundred strokes or so, I brushed the sandpaper clean and continued sanding. After about an hour and a half the ground glass side was uniformly milky, so I carefully washed it with soap and water, removed the masking tape, washed the glass again, patted it dry with paper towels and installed it in my camera.

It's beautiful and at least the equal in brilliance and smoothness to the commercial glass it replaced. I'm sure even better results could be obtained by using 220 grit aluminum oxde sandpaper, but -- of course -- I'd probably still be sanding.

At any rate, I was able to create a very nice ground glass in less than two hours without having to obtain exotic grinding grits from an astronomical telescope making supply house. Sure -- I'll make a glass the "right way" someday, but for now, I'm a happy guy.

If you follow this easy method of fabrication, please make sure you use aluminum oxide sandpaper and keep it, your glass, your workbench and your hands scrupulously clean as you work. Try it -- it works and it's (sorta) fun!

[Capocheny]

CR,

I usually have a couple of extra ground glass kicking around the camera closet so I never have to worry about not having one readily accessible.

But, it's always good to know how to make one... just in case!

Thanks for sharing!

Cheers

[C. D. Keth]

CR,

I usually have a couple of extra ground glass kicking around the camera closet so I never have to worry about not having one readily accessible.

But, it's always good to know how to make one... just in case!

Thanks for sharing!

Cheers

I made a new one (actually two...don't ask) for my 5x7. I started with 320 grit SiC and went down to 5 micron aluminum oxide. It' is MUCH finer grained than my old glass and I devised a test and measured it consistantly a stop and a third brighter than the old glass, too! It cost me $15 total for glass and grits and a full evening of my time.

[GPS]

1 1/2hr of sanding? You have my medal for patience! How about your arms? Were they able to lift the camera after that? Once I needed home made gg - when I started to sand it, I realized I'm not after the medal so I cut the sand paper for my circular rubber cone, put it on a drill and let the machine do the work for me. You have to change the sanding direction more often but it works. I finished it with a few hand strokes, the gg serves still today.

[geowulf]

I use my father-in-laws 'lap' table. it's a vibrating device that 'sands' the glass for me.

[Mark Sawyer]

In a pinch, the spray-on glass frosting from the local hardware store makes a nice "ground" glass in a few minutes.

[Glenn Thoreson]

I use fine grit valve grinding compound. The NoVue window frosting spray works well, too. For glass, I save the junk glass plates that show up around here. They're the perfect thickness. About the same as the commercial stuff that comes in the camera.

[SaveBears]

Wow, 2 hours! Yikes, the 4x5 screens I have ground normally take me about 10 minutes!

[Chauncey Walden]

As an experiment, I purchased a piece of 11x14 non-glare glass from Hobby Lobby for $9. It works for focusing, is very bright, but is too transparent for an overall view. It could be used for composing by moving you head around the screen. On the other hand, you don't need clipped corners to see the aperture! So, if you are on the road and break your only GG, emergency help is as close as your nearest Hobby Lobby or Michael's.

[Peter De Smidt]

Or in an emergency tape glass with a satin "scotch tape" style tape.