Ground or Etched?

[John Berry ( Roadkill )]

Going to be getting a new glass and wondered who prefers what and why. I know about the other types but this will be one or the other of these two choices. Thanks, John

[N Dhananjay]

Acid-etched glass involves treating the glass with fumes of hydrofluoric acid that can etch the glass while grinding involves scoring a sheet of glass with small abrasive particles to create a random scratch pattern. What I have heard is that acid-etched tends to be smoother and brighter (i.e., makes it easier to see details and focus) while the ground is coarser and somewhat more difficult to focus. On the other hand, some folks have argued that the process of grinding can be used to ensure that the focusing surface is truly flat (although I truly doubt this is an issue with etched glass, unless one was pouring the acid randoomly on the surface etc). I do find the acid-etched stuff to be nicer to focus on (although I suspect a well-made ground surface utilizing minute abrasives could be nice as well - unfortunately, most of the stuff tends to be nasty, coarse sandblasted stuff which works but not too well but they are probably responsible for the poor reputation of ground stuff). So, I think that is the difference - the acid etched stuff is a little more hard to do, so if you get it, odds are it would have been made decently. Ground stuff is a bit easier to do, so there seems to be comparatively more variance in quality. Some photo tech mag ran an article on making your own GG using really small abrasive particles and folks seemed quite pleased with the results. Have also been hearing good things about Stain Snow glasses (www.satinsnowglass.com) - sounds like they use good grinding techniques to ensure an even and small scratch pattern.

Cheers, DJ

[lee\c]

I have three formats that I have replaced the ground glass with glass from Satinsnow and I am very pleased. Bright glass and thin. I recommend getting the glass from SatinSnow.

leec

[Gem Singer]

John,

Acid etched is better, but more expensive. Satinsnow seems to be slow to deliver it's orders, but has been getting favorable comments (I suspect, partly because the price is so reasonable). Whether ground, or acid etched, if you're using a focusing screen that has grid lines, avoid the ones with black lines that are inked onto the glass. The focusing screens that have white, acid etched grid lines, are less distracting for composing the scene.

[matthew blais]

I have tried an acid etched (bought from Dagor77) and was not too impressed as it did not do any better than the glass that came on my old Korona 4x5. I have since replaced it with the Satin Snow and much better, brighter. For $10 bucks, it's awfully hard to beat. I keep the acid etched one as a backup.

For a whole lotta money more, you can get thte Beattie or Maxwell.

[John Berry ( Roadkill )]

The satin snow is one I have been looking at as it seems to have the qualitys that I was considering etched glass for. Thanks for the feedback, John

[Kevin Crisp]

I have tried Satin Snow in several sizes. It can take several weeks for it to arrive, they are buried with orders, it appears. (I ordered one 3/29, it arrived yesterday in the mail. This was for an Ikeda camera, which won't take the standard size listed on the website.) It is a very high quality ground glass. If you think you can spend $15 and get something as good as a Maxwell, etc. you will be disappointed. This is not a $15 miracle. If you want a very high quality ground glass, made to order and very well shipped by nice responsive people, you will be delighted. Combined with a light weight and cheap reading fresnel I get a very even, bright, sharp image which is completely acceptable. I haven't tried it bigger than 5X7, but in that size "hot spot" is minimal to non-existant, even without the fresnel.

[Eric Biggerstaff]

I have been making my own ground glass for some time using lens grinding powders that are very inexpensive. I like the results as the glass is very smooth and they are easy to make. They are bright, but not as bright as acid etched. I have no problem focusing them however.

[Eric Biggerstaff]

By the way, if you are interested in learning how to make your own groung glass go to www.phototechniques.com and then click on the "Articles" link on the left. Once done, look for the article "Making Your Own Ground Glass" by Dick Dokas.

The grinding powder is cheap and each bag will last a long time. I have made 4 ground glass for my camera (so I have several back ups) and the price would be about $3.00 each. Like I said, they are smooth and nice. Each takes about 30 minutes to make.

Just FYI.

[wcwiseman]

Eric: How about posting details of your procedure? The link you gave indicates one must "order and pay" for the information. An impoverished photographer trying to make his own ground glass is not likely to be able (or certainly reluctant) to pay for information. I believe in sharing information - that's one reason forums like this exist.
So, how about it? Tell us.
Details.
Thank you.

[Eric Biggerstaff]

Shoot, sorry everyone.

That article was free from the site several months ago and I just didn't pay attention to notice they now charge a fee (and the actual link is www.phototechmag.com).

The process is very simple but I am at work and don't have the article so when I get home tonight I will log back in and list the details.

But the basic is that you start with a sheet of normal window glass that you can get from any glass shop cut to the size of the ground glass you want to make. For a grinding tool, you will need an additional sheet of glass that is smaller (I use a small 3X3 inch square piece of glass for a grinding tool). Have the glass shop round off the edges (burnish) so they are not sharp. If you want clipped corners, the shop can do that as well. The glass will cost around $3.00 for each 4X5 inch piece.

Next you will need grinding powders that are used to grind telescope and camera lenses ( I will send this information later, it is easy to get a very inexpensive). I start with a corse grit of silcate and then work down to a finer grit. The coarse grit gets the glass 80% complete and the finer grit finishes it off.

Get a small container and add the powder with a small amount of water. The grinding paste should not be to thick, a little runny is best. Place a small amount on your ground glass, then place the ginding tool on top and begin rubbing in small circles all over the surface. As the paste drys out and rubbing becomes difficult, add a little more water or paste. Make sure the ground glass is on a flat surface ( I place it on a towel on the counter in my darkroom) so when you press your weight on the surface while grinding it won't crack.

Continue to use the coarse grit for about 20 mintues of solid grinding then wash the surface of the glass under running water. Now, you will repeat the process using the fine grit silicate.

The more time you spend the better the results but I can get a good ground glass in about 30 minutes and it is sort of fun as well.

Like I said, I will log back in and list the place where you can get the grinding powders. The process is easy and inexpensive.

Hope this helps.

www.ericbiggerstaff.com

[John Berry ( Roadkill )]

I am a retired deisel mechanic and used to rebuild fuel injecters. I still have my laping plate and some 1000 grit laping compound. I might just have to play around a little bit. With a 6'' lapping plate I would be able to make a very flat 8x10 peice of glass. The grit might be a little too fine for this aplication, but I can always step that up. Won't cost anything to play. John

[Ron Marshall]

What are the pros and cons of clipped corners on the GG?

I want to buy an etched GG, both to try and as a backup (I have already dropped mine twice), but I am not sure if I should get clipped corners.

[Paul_5410]

Interesting to find this topic since I have been preparing an order for some spare ground glass. I have one piece of 5x7 SatinSnow installed on my old japanese wood field.

For comparison; Using the same CP Goerz red dot APO Artar 270mm f:9 lens on all three cameras and the same tripod position as well. Trying to make only the ground glass the variable for the test.

Today I setup my Calumet/Tachihara 4x5 woodfield it uses a fresnel and gridded cover glass. Bright but using a 10x engineering lupe the lines between high lights and shadows where hard to see at infinity with soft lines. This seems the brightest but not the sharpess in shadow lines.

Next the Satin Snow, Bright, Clear and the branches on my tree at infinity are well defined, sharp and nice contrast. I'm ordering a 4x5 and 8x10 from Dave today.

8x10 Eastman 2D - Sinar Glass installed, fell in between the others on performance.

What acid etch glass I purchase last year came thick like an 1/8" or more??? Most of my cameras use slimmer products.

Finally as for cut corners, it is for air pressure to leave the bellows. . . if you are checking for corner rounding of lenses it is a problem but other than that most big bellows cameras come with cut corners.

Not real scientific but on topic for today anyway, Paul

[Eric Biggerstaff]

Well, cut corners also help determine if you have lens vignetting (sp) when using wide angle lenses. Once you stop down the lens down, by looking out the corners you can determine if the lens will completly cover the image area.

[Eric Biggerstaff]

I skipped out of work early to go photograph and along the way decided to finish what I started.

You can obtain the ginding powder from Willmann-Bell, Inc at 800-825-7827.

I recommend starting with the Aluminum Oxide 5 micron powder as the first step and then use the Aluminum Oxide 3 micron powder to finsih the grinding. If you do this you will have a very smooth and flat glass.

Also, you can get the acid etching gel for glass from any craft store (Hobby Lobby, Michaels) that you can try. I have never done it, but this weekend I might take a ground glass that I made and apply the acid etching gel to it as a final step. This should give me a very fine focusing surface.

What the heck, if it doesn't work I can always make another one!

Good luck.

www.ericbiggerstaff.com

[N Dhananjay]

I've tried the acid etching gel and it is hard to get an evenly etched surface. I think it probably works if you are doing crafts kind of stuff where you just want to frost part of the glass for contrast against the unfrosted stuff, but I found it very difficult to get an even frosting across the entire sheet of glass. Cheers, DJ

[Juergen Sattler]

I am using Satinsnow glass on all my LF cameras. It is very easy to ficus with and is the greatest value out there. Excellent glass!

[baz]

I read this topic because my 8X10 gg got broken. I saved Dokas article into a web archive. Write me, I will send you by mail. (I would it inserted on my site but I think isn't the best way due to the fact that's for money now...)

regards.

[Pete Skerys]

The details about gg grinding are on Dick Dokas's site:

http://www.dokasphotos.com/techniques/ground_glass/

i'm going to give it a go... doesn't look too difficult... just gotta find some grit.

has anyone had any luck with this yet?

[Randy_5067]

I, like others, tried the etching gel from the hobby centers, and like them, could not get a good even cover. BUT... what I did do, after I acid etched the glass, I took 600 wet-dry sanding disc on a palm sander, with some very-fine polishing powder, water, and about two minutes of work had an excellently great looking piece of glass. It amazingly turned out exceedingly vibrant and clear to focus with. I purchased the 5x7 glass in a used photo frame for 25 cents at the thrift store, 50 cents for the sanding disc, 2 dollars for enough polishing powder to last nearly forever, and 3.50 for the etch gel at the hobby store. So, a little over a buck for a really decent 5x7 glass ain't too shabby. And for the time spent, make a dozen a day for the just-in-cases. The etch gel gets a good start, and you can take pinstripe tape and lay out your grid patterns prior to etching, finishing, and then remove the tape. The very-fine grit, along with 600 wet paper puts a nice smooth finish to the glass. Doesn't look like Mt Everest through a loupe. And the best part is, when somebody comments on the clarity of the gg, you can puff up and tell 'em "Yep. I made that myself"