From: Jack Fulton (jefulton1@attbi.com)
Date: 02/22/03-06:34:54 PM Z
Thanks Pete . . .I'm going to give it a go.
Jack
> Jack,
>
> The simple answer to your query is I just donšt know. I have tried
> 5% of acetic acid with little effect but this a weak acid in comparison to
> sulphuric and I have not tried muriatic.
>
> However I know that a 5% sol of hydroxide will also do the trick. Some
> more scientific experimentation needs to be done. It may be that the strong
> acid or alkali softens the tanned colloid allowing the oxidation by products
> to leach out and desolve into the water solvent. all I am certain of is a
> 1% solution of sulphuric acid has neutralised the
> yellowish/greenish/brownish stain in my TemperaPrint very effectively for
> the past ten years with no apparent side effect.
>
> Pete
>
>
>> Pete:
>> This is an interesting idea . . is it the acid? Could one use muriatic or
>> acetic acids in place of the sulfuric?
>> Jack
>>
>>> How about a 1% solution of sulphuric acid as a clearing bath this has worked
>>> for me in my TemperaPrint process.
>>>
>>> Pete
>>>
>>>> Richard,
>>>> One of the problems that I've always had with reversal deveopment is that
>>>> I never seem to get completely rid of the yellowish/greenish/brownish stain
>>>> left over from, I presume, the dichromate bleach, I've tried clearing baths
>>>> other than just the sulfite with not too much success. I tried the
>>>> permanganate bleach long enough ago that I've forgotten the results, but
>>>> obviously they weren't encouraging. Naturally, there is always the odd time
>>>> when everything comes out just right with no apparent change in technique.
>>>> I
>>>> think they (the great they) do that just to make us even crazier. Do you
>>>> have
>>>> any insight as to what might solve this problem?
>>>> One of the reasons that I pursued reversal processing in the first place
>>>> is that theory says that the more sensitive (and larger) film grains which
>>>> develop first, are then removed in the bleach leaving the finer half of the
>>>> silver bell curve to create the finished transparency. I would have to say
>>>> that my observations tend to bear this out, and make it tantalizingly worth
>>>> doing, especially with 35mm, and 4x5 can be extraordinary. They also bear
>>>> out
>>>> the fact that you have to be about as careful as is if you were exposing
>>>> color transparency film if you want consistant results. Thoughts?
>>>>
>>>> Bob
>>>
>>
>
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