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winger
04-05-2007, 02:56 PM
A friend of someone I know has some glass negatives. How safe is it to expose them to light for making prints? Does that depend on the method originally used? Just wondering before I get volunteered to make contact prints. I don't want to do anything to them that would harm them.

TheFlyingCamera
04-05-2007, 03:10 PM
They should be fine for contact printing. The place you might run into issues is trying to enlarge them. In an enlarger, you run the risk of the emulsion catching fire and exploding (if they are wet-plate negatives). Later dry-plate negs might just crack and flake off the glass from overheating. The safest thing to do is either contact print or scan and enlarge that way.

winger
04-05-2007, 05:09 PM
Thanks!

pentaxuser
04-05-2007, 07:10 PM
Ignorance was bliss in my case in that I was given glass negs which dated from the late 1920s. I know the date of one of the negs as it was a neg of a very elderly relative of my neighbour. Based on what the Flyingcamera has said they might have been dryplate negs.

They looked incredibly thin and fragile but I hadn't considered the risk under the enlarger. They contact printed and enlarged beautifully with no damage.

I may have been lucky. I cannot say what size they were but they were not much bigger than 3-4 inches so contact printing was really too small. So really I had no choice but to enlarge for a decent size print.

pentaxuser

TheFlyingCamera
04-05-2007, 08:04 PM
It will depend a lot on the condition of the negs to begin with, and how much time they need under the enlarger lamp to focus, compose and expose. If they don't get too much heat exposure, and are handled carefully, they should be fine.

Marv
04-05-2007, 11:14 PM
I have printed a literally hundreds of glass negatives over the years. 2X2 up to 10X12 or so. Anything 4X5 or smaller I was able to enlarge and never had a damage issue. The larger contacted well.

Some of the negatives yielded beautiful prints and nearly all were as good as the average modern print. I salvaged images that printed from f22 @ 1 second to wide open for 5 minutes. It's fun but trying.

Flauvius
04-06-2007, 03:24 AM
What do you folks use for a contract frame when you print your glass negatives?

Flauvius

Schlapp
04-06-2007, 03:35 AM
Small contact printing frames bought extremely cheaply on the auction site. Just about to POP print a small Wellington & Ward ortho glass plate exposed @1asa this morning taped into a koroll 24s and dev in R09 for 3 mins!

Monophoto
04-06-2007, 08:00 AM
What do you folks use for a contract frame when you print your glass negatives?

Flauvius

My experience is that a printing frame is not needed when contact printing from glass plates. The weight of the plate is enough to keep everything flat.

Photographica
04-07-2007, 06:49 PM
A friend of someone I know has some glass negatives. How safe is it to expose them to light for making prints? Does that depend on the method originally used? Just wondering before I get volunteered to make contact prints. I don't want to do anything to them that would harm them.

I have been receiving a lot of emails concerning glass negatives lately. So, I went through many of my past replies and compiled a list of notes that may be of help to you. There's no particular organization to the notes just random information.
Good luck,
Bill Riley
************ NOTES *************
ON CLEANING GLASS NEGATIVES:
As far as cleaning them... it's OK to clean the glass side with water and a mild glass cleaner. Be very careful to not get any moisture on the emulsion side. Do not attempt to clean the emulsion side with anything more than a very light brush to get dust off. I would not use a blower on that side either. The emulsion is extremely delicate. If you need to make prints and the negative has dirt that you cannot clean, have it scanned and then use a software program to correct any problem areas.
ON AGE
Glass negatives can date from pre 1880's to the 1940's and even to present day. Mostly you can date them by the pictorial content -- clothing style, buildings, automobiles, etc. For an accurate age, generally it would take an expert's personnel examination and even then it may be difficult.
ON VALUES OF GLASS NEGATIVES
Values for individual glass negatives vary greatly depending primarily upon the subject matter of the photo. Others factors including size, condition, and quality of the photo (clarity, exposure, etc) also effect the value. For example, a very nice 4x5 glass negative of a man standing in front of his house is worth less than a $1.00. But, if that man were Babe Ruth, it would be worth a few hundred dollars.
As a collector of glass negatives, I'm always torn when someone asks me if their negatives are worth anything. Certainly there can be no value put on the family interest of your negatives. On an open market however, their value could be from only a few cents to hundreds of dollars. Their value comes from their size, quality, condition, and mostly with subject matter. A picture of your Aunt would be a little value to most people unless your Aunt was famous (or infamous). Other popular subject matter includes sports figures, Presidents, public buildings or other structures, news events, ... Get the idea... Find me a glass negative of Babe Ruth or Abraham Lincoln....
ON DATING GLASS NEGATIVES
Glass negatives can date from the mid-1800's to the mid-1900's. I usually look at the subject matter to try to determine the date.
ON MAKING PRINTS FROM GLASS NEGATIVES
Making a photo from a glass negative is the same as making a photo from an equivalent size film negative. Most large photo stores should be able to help you find someone who can help. I don't know where you live, but if you check your phone book you should be able to find some help. By the way, stores that provide One-Hour services are not what you should be looking for. Look for a shop that provided a full range of photo services -- even better professional services.
An alternative is to find someone with a computer flat bed scanner that has a transparency adapter. Very easy to scan glass negatives with that equipment.
ON SCANNING GLASS NEGATIVES
The most important thing is you get a scanner with a transparency adapter.
It lights the negative from behind resulting in perfect reproductions of you negatives. You don't need a lot in software for most neg's. Mostly, I use the photo software that came with my scanner and Windows operating system. I use an HP 5370 scanner for my glass neg's. For real high resolution of film neg's I use an Epson 3200.... Great scanner for a real great price (even came with Photoshop Elements).
I also used an HP5370 flat bed scanner which has a 5"x5" transparency adapter. To successfully scan glass negatives you really need to use an adapter that lights the negative from behind. The software that comes with the scanner will scan the image as a negative. There is a setting in the software that converts the image to it's negative which results in this case as a positive image. You can then use the photo software that comes with Windows to crop, size, or otherwise enhance the image. One word of advise -- save the image as a .jpg file no larger than around 40K bytes for your internet site. Otherwise people will get tired of downloading large files and not view them.
The key to scanning glass negative is to use a transparency adapter. It back lights the transparency (glass plate in this case) while scanning from under it. Check out HP, Microtek, and Epson. They all have scanners of various degrees with this feature. Most, are very expensive if you need to scan a transparency larger than 5"x5". If your negatives are 5x7 consider only scanning them in as 4x5 or 5x5. There usually isn't an issue cropping off an inch on either side of most photos.
I think when you get a scanner with a transparency adapter you will discover just how easy it is to get a good scan of your negatives. I use an HP5370 with a 5"x5" adapter. Works great with 5x7 negatives too... just a bit of cropping on the sides.... 4x5 is simple.
Check out Microtek scanners and Epson as well. You should be able to find something reasonable under USD$300.
For your larger prints, I'd contact print and scan the photo. The cost of a scanner with a larger (8x10) transparency adapter goes way up in price.
Also, I wouldn't go too crazy with the software. I use the photo editor that comes with Windows for most of the pictures -- mostly for cropping, negative reversal, and auto balance control. I'd be very careful putting the negative directly on the scanner's glass. While I have not experienced it, I've heard other voice concerns over scratching the scanner's glass surface. A thin mask made of paper is easy enough to make and will insure that you do not scratch the scanner.
Scan with the emulsion side next to the glass. You want the light to shine through the glass then through the emulsion before it is sent to the scanner sensors. The glass is not always the best optical medium for images… sounds odd but think about it and it will make sense.
ON STORING GLASS NEGATIVES
I recommend using acid free paper. You can buy it by the ream at almost any office supply store. It's fairly cheep. You can make folders for each negative by cutting and folding a sheet of paper. Also, you can put notes on the outside for reference. Store the negatives on edge (not stacked) in a cool dry location. I recommend you get some good digital scans of the negatives made and put on a CD. Then put the originals away. Try to document as much as you can about the people and places in your pictures.

Jim Jones
04-14-2007, 07:22 PM
Bethe -- you have enough information above to do the job. Go for it. Amateurs have usually preferred film for the past 100 years. Many pros used glass plates until much later. Even when they were originally intended to be contact printed, the camera work could be first-rate. Thus, there was photography of remarkable quality done on glass plates. The opportunity to work with them is illuminating. Of course not all photographers made the most of the medium, but it is still worthwhile volunteering for the job.

Sparky
04-14-2007, 07:25 PM
They should be fine for contact printing. The place you might run into issues is trying to enlarge them. In an enlarger, you run the risk of the emulsion catching fire and exploding (if they are wet-plate negatives). Later dry-plate negs might just crack and flake off the glass from overheating. The safest thing to do is either contact print or scan and enlarge that way.

Hey - how do you figure they risk fire or explosion. To my recollection - that has ONLY to do with nitrocel film bases. Glass, in my experiences tends not to spontaneously combust...

seawolf66
04-29-2007, 07:49 PM
I am in the process of unpacking some stuff that has been stored for a long while and I ran accross Two Plate Positive's , Which I am not familuar with any thoughts on these positive Plate fotos! :confused:

Ole
04-30-2007, 01:26 AM
Positive plates are called "Lantern Slides". Look it up.

TheFlyingCamera
04-30-2007, 07:04 AM
Hey - how do you figure they risk fire or explosion. To my recollection - that has ONLY to do with nitrocel film bases. Glass, in my experiences tends not to spontaneously combust...

If they are made with collodion, they ARE nitrocellulose based. Collodion is a form of nitrocellulose. If they are later dry plates, then no.

mcgrattan
04-30-2007, 08:02 AM
We scan a lot of glass plates at work [I work in a studio that deals mostly with old manuscripts, I'm the IT guy though, not a photographer].

We have one to do soon which is about 3ft across. I did a few experiments just placing larger plate negs on a lightbox and photographing from above. The results were surprisingly good.

Sparky
04-30-2007, 05:45 PM
Really? Okay... hmmm... I stand corrected. Didn't know it. However - there would be absolutely NO danger of anything exploding unless it were in a sealed container of really small volume and the decomposition rapidly proceeding - which probably wouldn't be happening by now - I'm guessing that any major changes to the emulsion would have been happening in the first 20-30 years... but hey, weird things happen.



If they are made with collodion, they ARE nitrocellulose based. Collodion is a form of nitrocellulose. If they are later dry plates, then no.