Re: Gum - what am I doing wrong?

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From: pete (temperaprint@blueyonder.co.uk)
Date: 04/09/02-04:29:55 AM Z

Hi Alberto and Hamish

>> On 09/04/2002 09:27 Hamish Steward wrote:
>>
>> Ammonium dichromate is not recommended - used it for years myself until
>> someone made me take a proper look. It stains much more than potassium is
>> harder to clear out of the print. Use a 15% solution of potassium, its a
>> little slower but gives cleaner results.
>
> Max. solubility of pot. dichromate at room temperature is about 8%. How can
> you get a 15% solution?
>
> I use ammonium dichromate 27% (slightly less than its maximun solubility) and
> yes, it stains. But a long soak in plain water overnight (one day after the
> complete dryness of the print) clears the print perfectly. I use to give more
> than 10 coats of different colours but in this way I am able to get rid of the
> yellow dicrhromate stain.
>
> Alberto
>
> http://spazioweb.inwind.it/albertonovo/index_eng.html
> http://www.grupponamias.com/novo/index_en.htm

I have used a 1% solution of sulphuric acid to clear my TempaPrints for the
past 15 years it clears as sweet as a bell no residual stain.

Pete

-- http://www.books.i12.com/parlour/tempera.html

 

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