Mixing Pextral's Two Bath; Substitute for Sodium Hydroxide?

Justin Low · Jun 26, 2007

Thanks for the advice. I've tried a roll with solution A consisting of 1% catechol, 0.5% ascorbic acid, B of 5% sodium carbonate.

See from this picture on: http://www.flickr.com/photos/justinlow/630686605/

I don't see a difference in the degree of graininess, or any substantial change. I will probably give it one last go with sodium sulfite in place of the ascorbate, but I'm not too optimistic about grain reduction.

Looks like I shall be sticking with Pyrocat-M for now.

Ole · Jun 26, 2007

Murray Kelly said:
In a 2-bath the carbonate is reusable.
Murray

In Pextrals, the alkali bath is resuable. But as soon as you turn the light on you will wish to discard it even after one single use; for reuse keep the light off.

It looks dreadful and gungy...

z-man · Jun 26, 2007

sodium/magnesium ascorbate as buffered vit c

gainer said:
If you want to add ascorbic acid without changing the acidity of the solution, mix it with baking soda in a little water and wait for the effervescence to subside before adding it to the solution. 1 level teaspoon ascorbic acid plus 1/2 level teaspoon of baking soda (sodium bicarbonate) in a couple of ounces of water gives the equivalent of 4 grams of ascorbic acid at near neutral pH.

sodium/and/or magnesium ascorbate powder avilable here in nyc health/whole food stores in 8oz and up

it seems people object to the acidity of ascorbic acid-i was looking for straight ascorbic acid and no one carries it here unless you buy it in caps-easy to measure out 1 gr am a time but very costly

now foods website says that sodium ascorbate is made by combining ascorbic acid and baking soda

hey gadget-can you direct me to your articles re anti freeze for mixing non oxidising vit c formula??

i can't spend more than 15mins at a time in front of crt due to damage to 5 cervical vertebre without having to double my morphine load and then i nod out and wake up 2 hrs later so a link or 3 would be much appreciated

vaya con dios

gainer · Jun 27, 2007

First, sodium ascorbate is very soluble in water but not in glycol or TEA. Ascorbic acid is available from NOW Foods and from www.chemistrystore.com. Magnesium ascorbate is, I think, not very soluble in either water or glycol.

I don't remember the issue, but the original article describing the use of antifreeze was in Photo Techniques magazine, which has an internet site. I think you can search it. Automobile antifreeze is nearly all glycol. The ordinary one is ethylene and the "safe" one is propylene glycol. The propylene glycol as well as TEA also are available at www.chemistrystore.com at about $16 per gallon + shipping.

Can you not get or have someone make an overhead mount for your display so that you can view it from a reclining position with more support for your head to take the strain off your spine?

Any of my recipes in APUG that call for glycol can use automobile antifreeze. When I was able to get the straight glycol, I substituted ounce for ounce for the antifreeze. You get some color with the antifreeze, free of charge.

gainer · Jun 27, 2007

I forgot to say that the web site for Photo Techniques is www.phototechmag.com.

srs5694 · Jun 27, 2007

Z-man, one of the sites I referenced earlier has the PC-Glycol formula, but not the whole article from Photo Techniques. If you want the whole article, the magazine sells back issues, although I can't promise the relevant one is still available. (It was when I bought it a couple of years ago.)

Concerning using automotive anti-freeze as a source of glycol, I've seen some people caution against this because you don't really know what's in it, and therefore whether the additives could have negative photographic effects; however, I have yet to see a report of it causing serious problems. I mixed up some PC-Glycol using "eco-friendly" anti-freeze in May of 2005 and it's still going strong. I've also bought various chemicals, including ascorbic acid, from The Chemistry Store, which Gadget Gainer has just referenced. They seem reliable and inexpensive, although their shipping charges are a bit on the high side, IMHO. (They tack on a separate "handling" charge, IIRC, which they don't mention until near the end of the order process.)

z-man · Jun 27, 2007

good info all around

gainer said:
First, sodium ascorbate is very soluble in water but not in glycol or TEA. Ascorbic acid is available from NOW Foods and from www.chemistrystore.com. Magnesium ascorbate is, I think, not very soluble in either water or glycol.

I don't remember the issue, but the original article describing the use of antifreeze was in Photo Techniques magazine, which has an internet site. I think you can search it. Automobile antifreeze is nearly all glycol. The ordinary one is ethylene and the "safe" one is propylene glycol. The propylene glycol as well as TEA also are available at www.chemistrystore.com at about $16 per gallon + shipping.

Can you not get or have someone make an overhead mount for your display so that you can view it from a reclining position with more support for your head to take the strain off your spine?

Any of my recipes in APUG that call for glycol can use automobile antifreeze. When I was able to get the straight glycol, I substituted ounce for ounce for the antifreeze. You get some color with the antifreeze, free of charge.

gadget you are priceless

i remember when you published the original articles-but my collection of back issues is no more

do you remember the guy who worked out a paper emulsion based on copper? he used pool supply copper sulphate-or was that you?

re my issues with crt placement-my new apt(3 yr old bldng!) walls and ceiling cant handle standard industrial mnts! am trying to find one of the desks that mnts the monitor with the screen looking up at you-just like you are reading a book-i'm good if i look down-thanks for the input on that

i went to nowfoods.com but all i get is a list of stores in my area and they all don't have the ascobic acid powder-i had hoped to order direct from the site but no go

so now i can look forward to both bastille day and gadget gainer's 80th-this will be a memorable event

vaya con dios

gainer · Jun 28, 2007

I think that if you look at the Chemistry Store web site you may find enough things you want to make the shipping cost worthwhile. Be aware that erythorbic acid is an isomer of ascorbic acid that functions just as well in photo chemistry and may be a little less expensive. Also, ascorbic acid is available in two grades, the cheaper of which is not to be used as vitamin C, perhaps because it is a mixture of the isomers.

They can put a gallon each of propylene glycol and TEA plus several pounds of other stuff in one box, which sometimes makes the shipping cost per pound go down.

Justin Low · Jun 30, 2007

Would a borax second bath give finer grain? I tried searching for catechol and borax, and I found a note on incompatibility, but details were scant. Can anyone help? Thanks!

Alan Johnson · Jun 30, 2007

Threshold of development of pyrocatechin is reported about 9.5,see last post here:
http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00APsE
pH of Borax is about 9.2, sodium metaborate 11.1.
Metaborate might work with long development.Place your bets.

Mixing Pextral's Two Bath; Substitute for Sodium Hydroxide?

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