Re: hp and pot di with pt/pd

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From: Manuel Gomes Teixeira (punctumgt@netvisao.pt)
Date: 04/10/03-09:40:11 AM Z


**Sorry if is this message was send twice to the list but I wasn't sure it
worked in the first try **

--------------------

And with Na2 , do you use it as direct substitute for K2ptCl4 ?

For example

9 drops FeOx
1 " Pt
2 " Na2
6 " Pd
to increase contrast , instead of

9 drops FeOx
3 " Pt
6 " Pd

??

Thanks again for useful advice. :-)

Manuel

> From: Eric Neilsen <e.neilsen@worldnet.att.net>
> Reply-To: alt-photo-process-l@sask.usask.ca
> Date: Thu, 10 Apr 2003 07:50:13 -0500
> To: alt-photo-process-l@sask.usask.ca
> Subject: RE: hp and pot di with pt/pd
>
> Manuel, I don't mean to imply very fast, but certainly faster than the
> ferric. Different papers will react differently to the addition of Pot
> Ch, so some may see quite a change rather quickly. Adding H2O2 to a
> developer is not the best way to go, as it does react with platinum both
> in the sensitizer/coating solution and within the developer.
>
>
>
>
> Eric Neilsen Photography
> 4101 Commerce Street
> Suite 9
> Dallas, TX 75226
> http://e.neilsen.home.att.net
> http://ericneilsenphotography.com
>
>
> -----Original Message-----
> From: Manuel Gomes Teixeira [mailto:punctumgt@netvisao.pt]
> Sent: Thursday, April 10, 2003 3:04 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: hp and pot di with pt/pd
>
> Eric ,
>
>
>
> Thanks for your reply.
> If I understood well both the Pot Chlorate added to the FO or in their
> own
> solution quickly looses its original characteristics and contrast
> control
> very fast. So in what way Pot Chlorate as more predictable results
> than
> H2O2 as Kerik said ?
> As I said , I've always got better results with H2O2 than with Pot
> Chlorate.
>
>
>
> Manuel Gomes Teixeira
> Punctum Studios Ltd
> Aveiro
> Portugal
> EU
>
>> From: Eric Neilsen <e.neilsen@worldnet.att.net>
>> Reply-To: alt-photo-process-l@sask.usask.ca
>> Date: Wed, 09 Apr 2003 22:44:38 -0500
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: RE: hp and pot di with pt/pd
>>
>> Manuel,
>>
>> Because you have not read all that has been written on this. Ted Rice
>> in Santa Fe was the first printer that I knew that did just that.
> Every
>> time you open a bottle of Ferric Oxalate with the Pot Chlorate added
> to
>> it, you can smell the small release of chlorine. The bottle loses its
>> ability to adjust contrast upward. You can mix fresh batches of a
>> potassium chlorate solution each time you print. The hard part about
>> this approach is that it only requires a small amount to have an
> effect
>> that an accurate measurement may prove too difficult for many.
>>
>>
>>
>> Eric Neilsen Photography
>> 4101 Commerce Street
>> Suite 9
>> Dallas, TX 75226
>> http://e.neilsen.home.att.net
>> http://ericneilsenphotography.com
>>
>>
>> -----Original Message-----
>> From: Manuel Gomes Teixeira [mailto:punctumgt@netvisao.pt]
>> Sent: Wednesday, April 09, 2003 6:40 PM
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: Re: hp and pot di with pt/pd
>>
>> Kerik,
>>
>>
>>
>> Tomorrow I'm going to order Na2 for the first time from B&S.
>> It will be interesting and useful for all of us to hear some more
>> details
>> of your and others experiences with this method of contrast control
>> in
>> Pt/Pd printing.
>> I suppose that you use NA2 in substitution of K2PtCl4 when printing
>> with
>> the classic Pt/Pd approach. Is that so ? Or is there any other more
>> complex procedures advised ?
>>
>> Until now I've had better results with H2O2 added to the sensitiser
>> solution than with Potassium Chlorate.
>>
>> My last question for today:
>>
>> Why in all Pt/Pd literature is never advised to use Potassium
> Chlorate
>> solution added to the sensitiser as H2O2 and instead is added
>> previously to
>> the Ferric Oxalate solution ? Is there any chemical explanation for
>> that ?
>>
>> Thanks for your time ! :-)
>>
>>
>> Kindest regards from Portugal
>>
>>
>> Manuel Gomes Teixeira
>> Punctum Studios
>> Aveiro
>> Portugal
>>
>>
>>
>>> From: Kerik <Kerik@kerik.com>
>>> Reply-To: alt-photo-process-l@sask.usask.ca
>>> Date: Wed, 09 Apr 2003 11:09:12 -0700
>>> To: alt-photo-process-l@sask.usask.ca
>>> Subject: Re: hp and pot di with pt/pd
>>>
>>> Christina,
>>>
>>> HP in the developer will increase contrast somewhat, as others have
>> stated.
>>> However, I really don't recommend this approach. The HP is quite
>> unstable
>>> and the developer contrast character will likely change during the
>> course
>>> of a single printing session. Enough to drive you nuts and waste time
>> and
>>> materials.
>>>
>>> Sodium dichromate is more commonly used as a developer additive
> rather
>> than
>>> potassium, although I would think potassium would provide similar
>> effects
>>> if you balance the quantity of the dichromate relative to sodium. I
>> say
>>> this because this approach has been standardized (by Phil Davis, I
>> believe)
>>> based on a drop count of 50% sodium dichromate solution per a given
>> volume
>>> of potassium oxalate. If you were to use potassium, I believe you
>> would
>>> have to use more of it since it will only exist in solution at a
>>> concentration of about 11%.
>>>
>>> And finally, if you haven't already, I really recommend experimenting
>> with
>>> B&S's "Na2" contrast agent which is added to the sensitizer rather
>> than the
>>> developer. It gives you a much wider range of contrast adjustment
> than
>>> available with the dichromate approach, and it doesn't cause the
>>> degredation of print quality associated with the "Ferric Oxalate No.
>> 2"
>>> approach that causes so many people problems when the are starting
>> with
>>> this process.
>>>
>>> Kerik www.Kerik.com
>>>
>>>> Good morning!
>>>> Does anyone use either hydrogen peroxide or potassium dichromate
>> added
>>>> to the developer or hp added to the sensitizer (the latter not for
>>>> palladium)?
>>>> Correct me if I am wrong here: added to the developer, dichromate
>> will
>>>> increase contrast? And hp will decrease contrast? Why does this
>> happen?
>>>> Chris
>>>
>>>
>>
>>
>>
>>
>
>
>
>


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