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View Full Version : Borosilicate Ground Glass - Grinding Your Own?



Len Middleton
30-Sep-2011, 21:33
Recently acquired an 8x20 camera project, and put the ground glass that came with it on, and found it quite dim.

So while I have not yet tried grinding my own ground glass, but am wondering about taking on grinding an 8x20 ground glass. And wondering about doing it in borosilicate.

Thoughts, comments, WTF, please ... :eek:

Thanks,

Len

lenser
30-Sep-2011, 21:39
To be honest, when I recently worked on restoring a studio Century camera, I simply went to a local glass shop and for about $20 bucks I bought a cut to order sheet of frosted glass. It is bright, it focuses accurately, it was quite reasonable on price and I couldn't be happier.

E. von Hoegh
1-Oct-2011, 07:14
Recently acquired an 8x20 camera project, and put the ground glass that came with it on, and found it quite dim.

So while I have not yet tried grinding my own ground glass, but am wondering about taking on grinding an 8x20 ground glass. And wondering about doing it in borosilicate.

Thoughts, comments, WTF, please ... :eek:

Thanks,

Len

Why borosilicate? The only advantage to it is that it has a low coefficient of expansion, glassware like Pyrex is a borosilicate glass. Can you even get it in thin sheets?

Nathan Potter
1-Oct-2011, 07:39
I have ground borosilicate often in the past. No different than grinding soda lime. 600 or coarser 400 grit silicon carbide in water with a few drops of Photoflow work fine. Use a smaller blank of glass for the motion surface; or I use a stainless steel grinding block.

As mentioned in earlier threads it's probably safer to grind a larger sheet first then cut to size rather than try to grind to the edge of the sheet where there is increased risk of edge cracks. OTOH if you've spent a lot of time grinding, and you are somewhat of a klutz, you don't want to break the screen :( cutting it after grind.

Nate Potter, Austin TX.

David Karp
1-Oct-2011, 07:51
If you decide not to do it yourself, Steve Hopf makes GGs out of borosilicate.

D. Bryant
1-Oct-2011, 07:55
If you decide not to do it yourself, Steve Hopf makes GGs out of borosilicate.

I agree, I think that is your better option.

dsim
1-Oct-2011, 08:06
There are instructions for DIY glass on Steve Hopf's website here (http://www.hopfglass.com/how-to-make-your-own-ground-glass).

Len Middleton
1-Oct-2011, 08:21
If you decide not to do it yourself, Steve Hopf makes GGs out of borosilicate.

David and Don,

Steve Hopf was / is a consideration. There is comments on his site regarding the benefit of the borosilicate glass.

However, it was after reading the various threads (Joe Forks, Ian Grant, etc.) on how to do it yourself and the link to the Hopf web site on DIY, that I have considered the DIY approach. In looking at the pricing by Steve Hopf, for ULF it is priced at $1 per square inch for soda lime, and twice that for borosilicate. So for an 8x20, it is 160 square inches, and for standard soda lime glass that is obviously $160, while borosilicate is twice that.

My wife and daughter are both into knitting. The amount of time involved in knitting the same sweater is going to be close to the same regardless of whether one is using cheap acrylic yarn, or an expensive alpaca / wool blend. If one is going to invest significant time, then using the better material will result in a sigificantly better final result, for the incremental different in material costs. Is that a resonable analogy here?

The cost of the borosilicate glass will be more expensive than the soda lime glass, but does it require more effort? Or is it likely to increase the probability of getting it wrong (e.g. scratches, etc.)? Will the final result likely be worth the additional effort and cost involved (i.e. incremental cost issue)?

Thank you for your insights thus far,

Len

PS dsim, I was likely composing when your comment was posted, so I did not read it before this post here.

cdholden
1-Oct-2011, 08:30
Why borosilicate?

It is more durable than regular plate glass, making it harder to break. When it does break, it breaks in larger pieces. This makes for a mess that's easier to clean up than smaller splinters and shards.

If breaking glass is a concern, consider acrylic plus a fresnel.

E. von Hoegh
1-Oct-2011, 08:37
Thanks; I was just perusing Hopf's website.
I never thoght of using it, I have to make a new GG for a 4x5 back one of these days, maybe I'll give it a try.:)

David Karp
1-Oct-2011, 08:42
Just putting it out there as an option. It is obviously expensive, but sometimes there are those projects that you just can't get to. I have a few of those!

And your post reminded me that I have to get a new GG to replace the 5x7 GG that I dropped in Kings Canyon in August. :-(

I was thinking of getting a Hopf borosilicate after that experience! And yes, it would be nice not to have to pick up all those small splinters, etc. if I ever break another.

TheDeardorffGuy
1-Oct-2011, 09:56
On my 12x20 I had the last sheet of Deardorff GG screen printed with the lines. Great bright glass. The clear lines help in the illusion of brightness. ALOT. So then my knee went into it a few years ago I was a bit ticked off (abto). I was in the middle of Illinois
on a Saturday afternoon at a tractor show doing a WA Panorama. I took the back to the Friendly Ace hardware store and had the kid cut a 12x20 sheet of 1/8 Lexan. (he had a sheet that was 15x20 in the scrap box) The sheet was 2.00 and a buck to cut it. Then 6.00 for a spray can of Krylon clear flat. I LOVE this method. First you can't break it. Second it is very flat, third anyone can do it. And you control the flatness of it. Spray about 18inches away and move across the class in say 3 sec and its fairly matte. faster and its clearer. cheap and easy and lighter than glass. I've drawn lines on it and used mineral spirits to remove the krylon. No damage to the lexon at all. You can buff it like paint on a car to restore the gloss of the viewing side too.

Len Middleton
1-Oct-2011, 14:26
Just putting it out there as an option. It is obviously expensive, but sometimes there are those projects that you just can't get to. I have a few of those!


David,

I would like to use some of his product, but cannot or will not bring myself to justify it.

I am farming out those parts of the project (making some darkslides, checking back and film holders, making bellows, etc.) to those who can perform that work much better than myself, as I lack skills in certain areas, and currently time.

Based upon the comments by those grinding their own ground glass, it would seem to indicate that with some patience and intelligence, it is doable by almost any klutz's with some effort. I think I probably can meet that threshhold.

Thanks,

Len