A question on making ground glass...

[Eric Biggerstaff]

I make my own and the key is getting even pressure on the grinding glass, the smaller piece. The larger piece of glass you use to grind with, the less even the pressure becomes. A smaller piece allows you to apply more even and consistent pressure while you grind, at least that is my experience. Also, as noted, while you grind the slurry begins to dry and the glass will begin to stick so you want to be able to remove it easily. All in all, it is not a difficult thing to make.

Also, I keep frosted Scotch tape in my repair box in case I crack a ground glass, it works well in a pinch. I was out yesterday with a friend and his 8X10 blew over and his glass shattered, not much we could do with that except head home.

[IanG]

http://www.apug.org/forums/forum216/...us-screen.html

I've made a ground glass with rock polishing grit (since I had some around). Seems OK.

I make around 100+ screens a year using the method you've linked to. I started because I realised I needed around 10 screens and that was going to be expensive buying from the US. These days I either make new screens or regrind the old ones for all my restorations.

Back around 2008 I posted a thread on APUG comparing various screen brightnesses, basically I found a huge difference between screen. I put my Crown Graphic alongside my Wista with it's original composite fresnel screen both with 150mm lenses and there was around 4 stops difference. This was making the Crown Graphic hard to focus particularly as I usually had to use it hand held it already had a replacement screen from a leading US supplier (not Satin Snow) and I re-ground it and it was significantly brighter, I also added a fresnel, now it's only about 2/3rds of a stop less bright compared to the Wista.

Ian

[Tin Can]

I make around 100+ screens a year using the method you've linked to. I started because I realised I needed around 10 screens and that was going to be expensive buying from the US. These days I either make new screens or regrind the old ones for all my restorations.

Back around 2008 I posted a thread on APUG comparing various screen brightnesses, basically I found a huge difference between screen. I put my Crown Graphic alongside my Wista with it's original composite fresnel screen both with 150mm lenses and there was around 4 stops difference. This was making the Crown Graphic hard to focus particularly as I usually had to use it hand held it already had a replacement screen from a leading US supplier (not Satin Snow) and I re-ground it and it was significantly brighter, I also added a fresnel, now it's only about 2/3rds of a stop less bright compared to the Wista.

Ian

Ian's APUG tutorial is the post that got me making GG. I love making them and have been considering regrinding a few of my factory GG.

I recenty bought finer grit. Maybe tonight!

Thanks Ian.

[cowanw]

Ian's tutorial got me started too.
Finer grit is a trade off of a more evenly spread visualization versus a decrease in brightness. Coarser grits can be very bright. Fresnels are a whole other issue. but I think everybody has a way of seeing that is unique. some don't mind a hot spot with a bright screen and vice versa.
Be interested to hear if you do some finer grits.
For more bucks though the fine plastic Fresnel/GG's, are nice.

[Tin Can]

Ian's tutorial got me started too.
Finer grit is a trade off of a more evenly spread visualization versus a decrease in brightness. Coarser grits can be very bright. Fresnels are a whole other issue. but I think everybody has a way of seeing that is unique. some don't mind a hot spot with a bright screen and vice versa.
Be interested to hear if you do some finer grits.
For more bucks though the fine plastic Fresnel/GG's, are nice.

I am gentle with all equipment and don't backpack. I think mountain climbers absolutely need plastic and fresnel GG. I haven't YET broken a GG. Knock on wooden head.

[cowanw]

I wasn't thinking of breaking, but of the combination of brightness, and lack of a hot spot without troublesome Fresnel lines as with my other cheapo Fresnel's.

[WayneStevenson]

To answer your thought experiment? Hobby stores carry acid etching for glass. Works great. Even Walmart carries Testor's Dullcote. It's a clear matte spray found with the model kits. Hairspray would likely work just as easy.

If you like going to go the easy route for a great finish, sandblast your glass. Go through a hopper of rough, and a hopper of fine and you're good to go.

[Peter De Smidt]

Wayne, you've had good luck with the acid? I tried it a bunch of ways some years ago, and I couldn't get even results.

[WayneStevenson]

You know it has been almost ten years probably since I used the acid. And it was a challenge to get great results as it did require practice. Though usable results are instantaneous to get you through.

The etching bath I found worked better than the cream, unless the cream was diluted with water. Though the cream sometimes had chunks in it so you had to be creative in ways to get them worked out. And you had to do a few coats.

[JoeV]

I made a crude "ground plastic" from an 8.5"x11" plastic fresnel magnifier, purchased at Staples office supply store, for a homemade 8x10 box camera. The fresnel's reverse side is smooth, so I ground it using a random orbital sander and 600 grit emory. The result is a one-piece GG+fresnel that's still serviceable today. Sure, it's not as flat as a true glass GG, but flat enough, and lots cheaper. And I'm shooting paper negatives, so it's not like I'm wasting $8+ sheets of film with each shot (but that's a subject for another thread...).

~Joe