Glass Negative Carrier Leaking Light at Edges of Glass

[Jerry Bodine]

Has anyone found a source for small quantity black epoxy paint?

I made a glass negative carrier for negatives up to 5x7” for my Omega E6 enlarger, using AN glass on top and clear glass on the bottom. Glass purchased from Mike at Focal Point. I’ve discovered that light is leaking out from the edges of the glass due to refraction, I think. I queried Mike about that, seeking suggestions for a fix. He replied that others have experience the same issue and have used vinyl electrical tape as a temporary fix, but he suggested painting the glass edges with black epoxy paint for a more durable solution to the problem; he said small quantities of the paint should be available from art supply stores. I’ve not found a source for small quantity.

[LabRat]

Try India ink... It remains a very thin coating, holds to edges of glass well, and is reversable as needed...

Steve K

[Eric Woodbury]

It can be any color as long as opaque. Why not paint for models and miniatures? Or black sign paint.

[Drew Wiley]

Paint can flake off. Just use an ordinary black Sharpie pen.

[Keith Pitman]

Make a “curtain” around the opening where you insert your negative carrier using black ultrasuede. It’s very opaque, inexpensive, and easy to find.

[Jerry Bodine]

Make a “curtain” around the opening where you insert your negative carrier using black ultrasuede. It’s very opaque, inexpensive, and easy to find.

I've already made the curtain so I can continue printing, pending a fix that's more convenient (my curtain doesn't cover the leaking light around the backside of the "saucer-shaped" head as well as I'd like). I think I'll give the Sharpie a try. If it doesn't get the job done, I'll be back for more suggestions. Thanks, guys.

[Nodda Duma]

Sharpie is in the toolbox of any lens designer who actually handles optics as well. But so is India Ink which is more appropriate for what you are describing.

A Sharpie will probably not be satisfactory because, while it is good for touching up existing edge blackening or dispersing stray light paths, it is not 100% opaque and won’t be as effective in your application. It may work well enough but you will be able to see light coming through and it’s difficult to build up enough ink for 100% opaque.

India ink is what you want because it can be coated on 100% opaque and so is good for creating an initial edge black. There is a specific India Ink which many optical engineers use and call out on lens drawings for edging. Speedball Super Black #3338. Do you have a Michel’s or Hobby Lobby nearby? If so, you can find it there. Otherwise order online at Amazon. It is very common and cheap.

Here is what the bottle looks like. After you’re finished edging the glass you can use the rest to practice calligraphy. :) or keep it around to touch up blackening

https://uploads.tapatalk-cdn.com/20180728/c5781f3f765f56a355571dfefa404c2a.jpg

[Keith Pitman]

You can get black paint pens for touching up furniture and guns. The one for guns is from Birchwood Casey. The one I have for furniture is Mohawk Ultra Mark. The paint is thicker and denser that a Sharpie will deliver.

[Jerry Bodine]

...Speedball Super Black #3338. Do you have a Michel’s or Hobby Lobby nearby? If so, you can find it there. Otherwise order online at Amazon. It is very common and cheap. [/IMG]

Thanks for the info, Nodda. I'm off to our new Hobby Lobby nearby.

[Drew Wiley]

Or a bottle of "Black Cat" which is superior to ordinary India ink. Blick carries it.

[Nodda Duma]

Or a bottle of "Black Cat" which is superior to ordinary India ink. Blick carries it.

Long-term outgassing leaving a film on your glass is a problem with that stuff.

[Jerry Bodine]

Thanks for the info, Nodda. I'm off to our new Hobby Lobby nearby.

I suppose I should ask if there is a recommended technique/tools for applying the Speedball ink to the edges of the glass, e.g., is a primer of sorts necessary? Foam "brush" OK? Drying time like any other ink?

[Nodda Duma]

Clean the edge with isopropyl or acetone — just sort of a good practice — then use a small paint brush like what Bob Ross would use for painting happy little trees. I had a chuck or vacuum pen at work that I could put the lens on and turn as I painted, but at home I hold the lens between thumb and finger — gloved of course — and turn it as I paint the edge.

If you mess up you can clean it off with isopropyl and reapply.

[Drew Wiley]

Guess it depends on the exact formula of Black Cat. Mine dries fast and outgasses fast, even in this foggy climate. There might be a tad of glycol in it to enhance flow. Dunno. But any enamel paint outgasses much much slower. The vinyl used in some enlarger bellows is a vastly bigger problem in terms of glass "windshield smudging".

[Doremus Scudder]

Paint can flake off. Just use an ordinary black Sharpie pen.

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