Dags and intro

[CasedImage]

Hi Tyler, I think the blue tint is underdevelopment but the black spots are another issue. I had always thought that it was caused by exhausted fixer, but it can be the fixer only being sodium thoiosulphate or just by being old fixer can cause the problem. The addition of sodium sulphite to the Sodium thiosulphate fixer resolves these issues. Put more eloquently by a more informed source:

“My understanding is that sodium sulfite is an oxygen scavenger. The image in Becquerel dev’ment is made up of very small silver particles. As silver particle size decreases its surface area increases dramatically and therefore its reactivity. Dissolved oxygen in the hypo solution allows the sod. thio. to dissolve the Becq. dev’d silver of the image. Sodium sulfite takes up the dissolved oxygen thereby preventing the dissolution of silver and weakening the image. If you have a weak Becq.-dev’d image due to underexposure or underdevelopment the image may disappear. This is because in such a weak image the silver particles are extremely small. With Becq-dev’ment, silver image particle size increases with dev’ment time and the image gets stronger. If you leave a “conventional” paper print in hypo for a very long time (hours) it will “bleach” the image.

Second reason:

Sodium sulfite in a hypo solution also prevents the sodium thiosulfate breaking down to sulfur and sodium sulfite. If you mix a liter of of hypo sol’n (w/o sulfite) over time it will break down into sulphur and sodium sulfite and this can lead to black spots of daguerreotypes from the sulphur. Kodak Rapid Fix also contains sodium sulfite among other chemicals.”

www.CasedImage.com

[jdanforth]

Great to see new people here. I have no idea who you are and that really pleases me!

 

I gotta say that these two pics you’ve put up here look great. You really seem to have figured out your polishing, man. You’re more or less right regarding your assessment of the images but I wouldn’t throw ’em out necessarily. Blue in Becquerel dev usually means that the plate was overexposed and underdeveloped (nice trick to add to the arsenal if you ask me). The ice cream parlor was overexposed but not by too much. I wouldn’t throw it out.

 

Don’t sprinkle pepper all over your plates before you seal ’em.   Just kidding… mix new hypo every day and make sure to use distilled water. I’ve only ever gotten the pepper grain when I’ve been lazy and not made fresh hypo.

 

[Author]

Posts