Gilding solution

[bohemiansecret]

just a quick question re gilding solution.

In Jerry’s workshop book I have it says to mix gilding solution and let it sit for hours before use.

If I have gilding solution mixed how long before I need to use it up?

with thanks

 

sonia

[jgmotamedi]

I don’t have a definitive answer to your question, as I have not experimented much, but I have found that after sitting more than about three weeks mixed gilding solution starts to act funny and will leave stains on plates. I try to use my solution within a few days of mixing.

[bohemiansecret]

Thank you for your reply.

gratefully sonia

[jgmotamedi]

I try to mix my gilding solution the evening before, and, as much as possible, mix no more than I will use.

[Mike Robinson]

[Mike Robinson]

Old gilding solution (even a few days old) is likely to cause the plates to “break out” in tiny black specks of sulphur. Recently I have taken to make the gilding solution on a plate-by-plate basis. For my recent workshop, to gild a quarter plate, 10 mL of 0.2% gold chloride solution (pH raised with 10 drops of 2% sodium metaborate solution) was mixed into 10 mL of 1% sodium thiosulfate (anhydrous) solution. The mixed solution is orange coloured. It will clear after 2 or 3 hours, but I use it right away after filtering. It is still orange in colour. Interestingly the colour clears during the toning process. I use an alcohol lamp on a gilding stand for 3 or 4 minutes, sometimes but not often longer. To avoid stains I never handle the plate by the edges, particularly with bare hands and first pour distilled water on the plate so it fills the surface. The toner is poured directly into the standing water on the plate displacing some but not all of it.

Mike Robinson

[jgmotamedi]

Why do you change the pH Mike? Ken told me about this, but I couldn’t figure out what advantage it holds.

[bohemiansecret]

thank you Mike !! …

and yes to jg  why the change of ph?

I am touched by the heartful support by the  daguerreotype folks … thank you with all my heart …  I am screwing my plates passionately I feel so grateful to be able to ask across the globe … I can not express in words … just warm thanks and gratitude …

[Mike Robinson]

Early on,(14 years ago) I noticed that when I mixed my Part A (gold chloride solution) into Part B (hypo solution) the mixture was golden orange (tawny) colour that cleared after a couple of hours. When Irv Pobboravsky mixed his Part A and B together the solution was colourless right away. Irv and I did a few experiments (7/18/99) using my toner on his test target d’types. He was ecstatic to see a roughly 30% increase in contrast. Whites got whiter, blacks got blacker. With his toner, Irv was seeing a gain in blackness, but not as much brightening of the highlights. We then looked at pH to try to figure out the cause. My tawny solution had a pH of about 6.5 mixed, Irv’s about 4.5 mixed. The difference was due to the acidity of the gold chloride.
Not all gold chlorides are created equal.

Eventually my supplier in Toronto had to find another source and to my dismay, the gold chloride was more acid, like Irv’s. (1% solution had a pH of 1.5 ish, the less acid salt had a 1% solution pH of 2.5 ish)
I did experiments on raising the pH of the new gold chloride (HAuCl4.XH20 for those who care) Eventually, I found the best means to do this was adding about a drop per mL of pH+ (I call it pee-haitch plus) to the Part A BEFORE mixing it with the Part B (hypo).

Irv – have I remembered this correctly? I think Ken and maybe Rob were present as well.

Mike Robinson

[bohemiansecret]

thank you so so much Mike … such a grand community here

[New Alchemy]

I am having some problems with mt gilding solution This is the 2nd time this has happened When combining the gold solution to the hypo, it turns a blood red then into a dark coffee color. I mixed the gold solution about 3 months ago, gilded a few plates no problem with same solution. I have checked and double checked the formulation, exactly the same as been working successfully, all lab ware rinsed with distilled water, new brown bottle with compression cap. Does the gold solution have a shelf life? This is the 1% gold solution, not the mixed solution. again same batch and formulation worked fine when made 3-4 months ago. Has anyone else had this problem? or possible cause? Expensive problem, and the interment nature leaves me baffled.
Thanks, Dan K

[Author]

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