Date   

Re: OFF LIST RE: [altphotolist] Uranotypes

Richard Knoppow
 

I can't figure out why you wanted this off list. It seems to me to be exactly the sort of expert advice the list exists for.

On 5/29/2021 4:20 PM, BOB KISS wrote:

OOPSIE!I guess it wasn't off list!LOL!!!

--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL


Re: OFF LIST RE: [altphotolist] Uranotypes

ender100
 

That’s ok, I didn’t read it. 

Best Wishes,
Mark Nelson

www.PrecisionDigitalNegatives.com
www.MarkINelsonPhoto.com

Curve Calculator III for the Mac is Now Available

sent from my iPhonetypeDeviceThingy

On May 29, 2021, at 6:20 PM, BOB KISS <bobkiss@...> wrote:



OOPSIE!  I guess it wasn't off list!  LOL!!!

 

From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of BOB KISS
Sent: Saturday, May 29, 2021 6:52 PM
To: altphotolist@groups.io
Subject: OFF LIST RE: [altphotolist] Uranotypes

 

DEAR JIM,

            I am sending you this off list.  Please send me some results.  Here are some of the tricks:

1) Double coat.  But important to wait about 8 to 12 hours between coats!

2) Yes, I use potassium dichromate as a contrasting agent.  For a 16 X 20 piece of HPR, for EACH of the two coatings, I use 8 ml Uranyl Nitrate sensitizer (see below) 2 drops of PVA, and 18 drops of 1 % Potassium Dichromate.  I guess you could use 2 drops of 10% Dichromate (if that is what you mean by PD) but how would you control this for smaller prints?  Maybe a 5% might be a reasonable compromise of greater effect for fewer drops while still allowing control for smaller prints. 

3) Yes, it is a VERY slow process and I use either my Nu Arc for very long, bulb killing exposures or I use the sun with my UV dosimeter to get sufficient exposure.  A step wedge saves TONZA chems, paper and time.  Pretty much forget about UV fluorescent tubes!

4) DEVELOP TO COMPLETION!  This is the gremlin that gets most newbies in uranotype.  I develop for up to 4 minutes, until I have a DEEP burgundy brownish-reddish Dmax.  Anything less and you are wasting chems, paper, and time. 

5) Wash water MUST be neutral or even slightly acidified.  I use a BIG tray filled with water and a teaspoon of citric acid in each one, dumping, mixing fresh and doubling the time in each bath until I reach over a half hour.  THEN I rinse in distilled water before hanging to dry.

6) Uranyl Nitrate is VERY  slightly radioactive (low energy alpha and some weak gamma) BUT it is a very dangerous nerve toxin and carcinogen.  USE ALL PROPER LAB PRECAUTIONS AND PROCEDURES.

7) You probably know of the late Bob Schramm's informative page on UNBLINKING EYE:  https://unblinkingeye.com/Articles/Uranium/uranium.html 

            Here are his formulae which I have used since day one with great results

Uranotype Solution

Sensitizer

Uranium Nitrate

4 g

Distilled Water

16 cc

Developer

Potassium Ferricyanide

10 g

Distilled Water

300 cc

All of these solutions are reusable and keep well, but store them in well-sealed amber glass bottles.

                                                           

                                                CHEERS FROM BARBADOS!

                                                                        BOB

 

-----Original Message-----
From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of Jim Patterson,
Sent: Saturday, May 29, 2021 3:20 PM
To: Alt photo List
Subject: [altphotolist] Uranotypes

 

Hi Bob in Barbados,

I saw a YouTube of yours about Uranotypes in the past year.  I tried my first today.  Under exposed and needs some dichromate contrast control.  Do you use 10% PD?

Jim

 

 

 

 


Re: OFF LIST RE: [altphotolist] Uranotypes

BOB KISS
 

OOPSIE!  I guess it wasn't off list!  LOL!!!

 

From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of BOB KISS
Sent: Saturday, May 29, 2021 6:52 PM
To: altphotolist@groups.io
Subject: OFF LIST RE: [altphotolist] Uranotypes

 

DEAR JIM,

            I am sending you this off list.  Please send me some results.  Here are some of the tricks:

1) Double coat.  But important to wait about 8 to 12 hours between coats!

2) Yes, I use potassium dichromate as a contrasting agent.  For a 16 X 20 piece of HPR, for EACH of the two coatings, I use 8 ml Uranyl Nitrate sensitizer (see below) 2 drops of PVA, and 18 drops of 1 % Potassium Dichromate.  I guess you could use 2 drops of 10% Dichromate (if that is what you mean by PD) but how would you control this for smaller prints?  Maybe a 5% might be a reasonable compromise of greater effect for fewer drops while still allowing control for smaller prints. 

3) Yes, it is a VERY slow process and I use either my Nu Arc for very long, bulb killing exposures or I use the sun with my UV dosimeter to get sufficient exposure.  A step wedge saves TONZA chems, paper and time.  Pretty much forget about UV fluorescent tubes!

4) DEVELOP TO COMPLETION!  This is the gremlin that gets most newbies in uranotype.  I develop for up to 4 minutes, until I have a DEEP burgundy brownish-reddish Dmax.  Anything less and you are wasting chems, paper, and time. 

5) Wash water MUST be neutral or even slightly acidified.  I use a BIG tray filled with water and a teaspoon of citric acid in each one, dumping, mixing fresh and doubling the time in each bath until I reach over a half hour.  THEN I rinse in distilled water before hanging to dry.

6) Uranyl Nitrate is VERY  slightly radioactive (low energy alpha and some weak gamma) BUT it is a very dangerous nerve toxin and carcinogen.  USE ALL PROPER LAB PRECAUTIONS AND PROCEDURES.

7) You probably know of the late Bob Schramm's informative page on UNBLINKING EYE:  https://unblinkingeye.com/Articles/Uranium/uranium.html 

            Here are his formulae which I have used since day one with great results

Uranotype Solution

Sensitizer

Uranium Nitrate

4 g

Distilled Water

16 cc

Developer

Potassium Ferricyanide

10 g

Distilled Water

300 cc

All of these solutions are reusable and keep well, but store them in well-sealed amber glass bottles.

                                                           

                                                CHEERS FROM BARBADOS!

                                                                        BOB

 

-----Original Message-----
From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of Jim Patterson,
Sent: Saturday, May 29, 2021 3:20 PM
To: Alt photo List
Subject: [altphotolist] Uranotypes

 

Hi Bob in Barbados,

I saw a YouTube of yours about Uranotypes in the past year.  I tried my first today.  Under exposed and needs some dichromate contrast control.  Do you use 10% PD?

Jim

 

 

 

 


OFF LIST RE: [altphotolist] Uranotypes

BOB KISS
 

DEAR JIM,

            I am sending you this off list.  Please send me some results.  Here are some of the tricks:

1) Double coat.  But important to wait about 8 to 12 hours between coats!

2) Yes, I use potassium dichromate as a contrasting agent.  For a 16 X 20 piece of HPR, for EACH of the two coatings, I use 8 ml Uranyl Nitrate sensitizer (see below) 2 drops of PVA, and 18 drops of 1 % Potassium Dichromate.  I guess you could use 2 drops of 10% Dichromate (if that is what you mean by PD) but how would you control this for smaller prints?  Maybe a 5% might be a reasonable compromise of greater effect for fewer drops while still allowing control for smaller prints. 

3) Yes, it is a VERY slow process and I use either my Nu Arc for very long, bulb killing exposures or I use the sun with my UV dosimeter to get sufficient exposure.  A step wedge saves TONZA chems, paper and time.  Pretty much forget about UV fluorescent tubes!

4) DEVELOP TO COMPLETION!  This is the gremlin that gets most newbies in uranotype.  I develop for up to 4 minutes, until I have a DEEP burgundy brownish-reddish Dmax.  Anything less and you are wasting chems, paper, and time. 

5) Wash water MUST be neutral or even slightly acidified.  I use a BIG tray filled with water and a teaspoon of citric acid in each one, dumping, mixing fresh and doubling the time in each bath until I reach over a half hour.  THEN I rinse in distilled water before hanging to dry.

6) Uranyl Nitrate is VERY  slightly radioactive (low energy alpha and some weak gamma) BUT it is a very dangerous nerve toxin and carcinogen.  USE ALL PROPER LAB PRECAUTIONS AND PROCEDURES.

7) You probably know of the late Bob Schramm's informative page on UNBLINKING EYE:  https://unblinkingeye.com/Articles/Uranium/uranium.html 

            Here are his formulae which I have used since day one with great results

Uranotype Solution

Sensitizer

Uranium Nitrate

4 g

Distilled Water

16 cc

Developer

Potassium Ferricyanide

10 g

Distilled Water

300 cc

All of these solutions are reusable and keep well, but store them in well-sealed amber glass bottles.

                                                           

                                                CHEERS FROM BARBADOS!

                                                                        BOB

 

-----Original Message-----
From: altphotolist@groups.io [mailto:altphotolist@groups.io] On Behalf Of Jim Patterson,
Sent: Saturday, May 29, 2021 3:20 PM
To: Alt photo List
Subject: [altphotolist] Uranotypes

 

Hi Bob in Barbados,

I saw a YouTube of yours about Uranotypes in the past year.  I tried my first today.  Under exposed and needs some dichromate contrast control.  Do you use 10% PD?

Jim

 

 

 


Cyanotype/Cuprotype

Jim Patterson,
 

Hi All,
Here is a combo Cyanotype/Cuprotype I did a few years ago at Penland School of Craft.
Jim


Uranotypes

Jim Patterson,
 

Hi Bob in Barbados,
I saw a YouTube of yours about Uranotypes in the past year. I tried my first today. Under exposed and needs some dichromate contrast control. Do you use 10% PD?
Jim


Re: Screen Printing UV units and Dichormate printing

brittonie,
 

Hiya,

I’ve got both LED and bulb (self built) units and for dichromates or Diazo I prefer the bulbs the time is longer and yields a better print easier curve to correct. 

I think maybe if you’re just using it for screen printing then the halftone/bitmap is great for it fast and to the point with no worry about tonal range. 



On Wed, 26 May 2021 at 06:35, The Platinotypist <platinotypist@...> wrote:
Good morning
Yes, I still use UV blacklight tubes. They are self-built. Later I will send you some demonstration photographs, just the time to go to the two studios where there are groups that differ from each other in type of construction and size. I don't need to replace the tubes with LED strips. The prints are also very good both in terms of exposure time and irradiation capacity. I argue that if I have to replace the light source I would replace it with a mercury vapor lamp like the NuArc bulbs.
See you later!

--



BrittonieFletcher.com


Re: Screen Printing UV units and Dichormate printing

The Platinotypist
 

Good morning
Yes, I still use UV blacklight tubes. They are self-built. Later I will send you some demonstration photographs, just the time to go to the two studios where there are groups that differ from each other in type of construction and size. I don't need to replace the tubes with LED strips. The prints are also very good both in terms of exposure time and irradiation capacity. I argue that if I have to replace the light source I would replace it with a mercury vapor lamp like the NuArc bulbs.
See you later!


Re: Light Source Needed

 

Yes its self masking, but that is for shadows not highlights. We are talking about highlights in this case . . .

Best regards,
Walker

On May 24, 2021, at 5:39 PM, Greg Schmitz <lists@gregschmitz.com> wrote:


On 5/20/21 6:15 AM, Clay Harmon wrote:
The only downside I can think of for longer print exposures is they will create a higher contrast print. The old trick of exposing POP and salt prints in open shade to goose the contrast is an example of this.

POP is self masking - it builds density in exposed areas (shadows) and that inhibits further exposure. It's possible to do something similar with gelatin silver enlarging paper by soaking a piece of unexposed paper in developer, then squeegee or sponge of the liquid, and expose the paper using a negative in an enlarger.

--greg







Re: Light Source Needed

Greg Schmitz
 

On 5/20/21 6:15 AM, Clay Harmon wrote:
The only downside I can think of for longer print exposures is they will create a higher contrast print. The old trick of exposing POP and salt prints in open shade to goose the contrast is an example of this.

POP is self masking - it builds density in exposed areas (shadows) and that inhibits further exposure.  It's possible to do something similar with gelatin silver enlarging paper by soaking a piece of unexposed paper in developer, then squeegee or sponge of the liquid, and expose the paper using a negative in an enlarger.

--greg


Re: Light Source Needed

George L Smyth
 

I went ahead and got the lights at https://amzn.to/3wrH1SH.  They are not as impressive as some of the suggestions but they are working quite well - actually slightly better than the bank of six black lights I had been using (exposure for my Kallitypes went from 6 minutes to 5 minutes).  For less than $30 I have a replacement and am very happy with the choice.

Cheers -

george

--------------------------------------
Handmade Photographic Images: http://www.GLSmyth.com
Blog: http://GLSmyth.wordpress.com


On Saturday, May 22, 2021, 02:38:28 PM EDT, Gordon Holtslander, <gjholtslander@...> wrote:


Digikey seems to carry a wide range of UV LEDs


offers some filtering to select specific features.

Gord

On Wed, May 19, 2021 at 10:25 PM Kurt Nagy <KaKaroTT76@...> wrote:
George

Here are some 365nm LED strips that I was looking at as an option.  5m is sufficient to create an exclosure capable of doing 11x14 (I believe) so you're looking at $200 for just the strips, not counting any power source or other misc connectors.  I may eventually go this route but I'll probably try the cheaper option first

From: altphotolist@groups.io <altphotolist@groups.io> on behalf of Kees Brandenburg, <workshops@...>
Sent: Thursday, May 20, 2021 12:13:18 AM
To: altphotolist@groups.io <altphotolist@groups.io>
Subject: Re: [altphotolist] Light Source Needed
 
These Everbeam 365nm floodlights seem to be out of stock everywhere, also at amazon, at this moment.
https://shopeverbeam.com/products/everbeam-10w-led-uv-flood-light?variant=37429566865582
There are other brands but these are mostly in the higher wavelenths.

Kees



> On 20 May 2021, at 04:41, George L Smyth via groups.io <glsmyth=yahoo.com@groups.io> wrote:
>
> Sandy
>
> Would you happen to have a link to the unit? I've looked all through Amazon but have not had success finding such units. I am looking for something with a very low profile, so a flood light might not work for my purposes.
>
> Thanks
>
> george






Re: Light Source Needed

Gordon Holtslander,
 

Digikey seems to carry a wide range of UV LEDs


offers some filtering to select specific features.

Gord

On Wed, May 19, 2021 at 10:25 PM Kurt Nagy <KaKaroTT76@...> wrote:
George

Here are some 365nm LED strips that I was looking at as an option.  5m is sufficient to create an exclosure capable of doing 11x14 (I believe) so you're looking at $200 for just the strips, not counting any power source or other misc connectors.  I may eventually go this route but I'll probably try the cheaper option first

From: altphotolist@groups.io <altphotolist@groups.io> on behalf of Kees Brandenburg, <workshops@...>
Sent: Thursday, May 20, 2021 12:13:18 AM
To: altphotolist@groups.io <altphotolist@groups.io>
Subject: Re: [altphotolist] Light Source Needed
 
These Everbeam 365nm floodlights seem to be out of stock everywhere, also at amazon, at this moment.
https://shopeverbeam.com/products/everbeam-10w-led-uv-flood-light?variant=37429566865582
There are other brands but these are mostly in the higher wavelenths.

Kees



> On 20 May 2021, at 04:41, George L Smyth via groups.io <glsmyth=yahoo.com@groups.io> wrote:
>
> Sandy
>
> Would you happen to have a link to the unit? I've looked all through Amazon but have not had success finding such units. I am looking for something with a very low profile, so a flood light might not work for my purposes.
>
> Thanks
>
> george






Re: Cyanotype: White spots appearing as print begins to dry

Cinda Berry
 

Thank you all so much!

Cleaned the glass before those exposures but did not us a razor blade.  

All the suggestions are so appreciated.  I love the opalux and thought it was relatively foolproof.  It is also impossible to touch up.  




On May 21, 2021, at 10:30 AM, Diana Bloomfield, <dlhbloomfield@...> wrote:


I was going to say-- agree with Marek-- I suspect they are spots on your glass.  I use a vacuum print frame, and even when my glass looks pristine, I still have to go over it lightly with a razor blade, because there are leftover artifacts from previous printing sessions that I just don't see, and that don't seem to come clean with a glass cleaner.  I am aware only when the spots appear on my prints.  So a razor blade has become my best friend with the glass cleaning.

Diana



On Fri, May 21, 2021 at 10:25 AM Marek Matusz <marekmatusz@...> wrote:
They either look like spots on the glass or more likely outgassing during development. Try to float with the image face up and gently move it around during development and wash although these are usually lightly colored not totally white. 
Marek


On May 21, 2021, at 8:06 AM, Cinda Berry <Cyrreb@...> wrote:



Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Cyanotype: White spots appearing as print begins to dry

Christina Z. Anderson
 

Cinda,
If you’ve never seen this before, then I wonder if it’s the paper at fault.
Canson Opalux is a tricky paper. If the spots are perfectly round that may indicate some sort of bubble popping or viscosity popping where the surface isn’t absorbing evenly and it "fish eyes” for want of a better word. Is it possible there are particles in the paper that are less absorbent? 
This happens a lot in gum, but not paper related, with certain pigments and I just brush and brush until the spots disappear. 
It might be helpful to coat a piece of Opalux on top of a light box and see if you can see them happening.
Also if you coat another paper and it doesn’t happen by comparison.
But the sharp, perfectly round edge is telling. Water spots would have a softer edge.
I have also experienced cyanotype and palladium spots on my contact frame that held back light and every time that happens I want to kick myself.
Chris

On May 21, 2021, at 7:06 AM, Cinda Berry <Cyrreb@...> wrote:


Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Cyanotype: White spots appearing as print begins to dry

Cedric Muscat
 

If not a batch issue the spots as others mention on the glass should be visible under UV light...
Cedric Muscat









On Fri, 21 May 2021 at 16:25, Marek Matusz <marekmatusz@...> wrote:
They either look like spots on the glass or more likely outgassing during development. Try to float with the image face up and gently move it around during development and wash although these are usually lightly colored not totally white. 
Marek


On May 21, 2021, at 8:06 AM, Cinda Berry <Cyrreb@...> wrote:



Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Cyanotype: White spots appearing as print begins to dry

Marek Matusz
 

Another dead giveaway for glass spots is that that make same pattern on a different image 


On May 21, 2021, at 9:30 AM, Diana Bloomfield, <dlhbloomfield@...> wrote:


I was going to say-- agree with Marek-- I suspect they are spots on your glass.  I use a vacuum print frame, and even when my glass looks pristine, I still have to go over it lightly with a razor blade, because there are leftover artifacts from previous printing sessions that I just don't see, and that don't seem to come clean with a glass cleaner.  I am aware only when the spots appear on my prints.  So a razor blade has become my best friend with the glass cleaning.

Diana



On Fri, May 21, 2021 at 10:25 AM Marek Matusz <marekmatusz@...> wrote:
They either look like spots on the glass or more likely outgassing during development. Try to float with the image face up and gently move it around during development and wash although these are usually lightly colored not totally white. 
Marek


On May 21, 2021, at 8:06 AM, Cinda Berry <Cyrreb@...> wrote:



Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Cyanotype: White spots appearing as print begins to dry

Diana Bloomfield, <dlhbloomfield@...>
 

I was going to say-- agree with Marek-- I suspect they are spots on your glass.  I use a vacuum print frame, and even when my glass looks pristine, I still have to go over it lightly with a razor blade, because there are leftover artifacts from previous printing sessions that I just don't see, and that don't seem to come clean with a glass cleaner.  I am aware only when the spots appear on my prints.  So a razor blade has become my best friend with the glass cleaning.

Diana



On Fri, May 21, 2021 at 10:25 AM Marek Matusz <marekmatusz@...> wrote:
They either look like spots on the glass or more likely outgassing during development. Try to float with the image face up and gently move it around during development and wash although these are usually lightly colored not totally white. 
Marek


On May 21, 2021, at 8:06 AM, Cinda Berry <Cyrreb@...> wrote:



Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Cyanotype: White spots appearing as print begins to dry

Marek Matusz
 

They either look like spots on the glass or more likely outgassing during development. Try to float with the image face up and gently move it around during development and wash although these are usually lightly colored not totally white. 
Marek


On May 21, 2021, at 8:06 AM, Cinda Berry <Cyrreb@...> wrote:



Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.

<image1.jpeg>

Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Cyanotype: White spots appearing as print begins to dry

Cinda Berry
 


Things were great until yesterday, when small white spots (ranging from 1mm - 3mm ) started appearing on prints (NC on canson opalux vellum).

Prints were developed in Sulfamic acid bath (3 min), followed by 2 warm water baths (3 min each).  Constant agitation in each bath.   Humidity: 54; room temp: 68; tap water ph neutral.  

Spots do not appear until paper begins to dry.


Today before exposure and development, I 

- Cleaned all work surfaces and developing trays
- Poured sulfamic solution through filter 
- Used fresh blotting material 
- Read troubleshooting chapter in Christina Anderson’s book
- Googled. These spots are uniformly circular and hard -edged, not soft edged like the spots caused by stray citric crystals.  Spots are too small to be water spots 
- Before exposure, checked for bubbles in dried emulsion. There were none visible to naked eye.

… And the spots still appear on partially dried prints and are still there when the print is completely dry.

I have been using the same coating, exposure, and development methods for over a month and did not have the “spot problem” until yesterday.  I’d be grateful for any suggestions as to why these spots are occurring and what I can do to get rid of them. 

Thanks in advance!


Re: Light Source Needed

Robert Poole
 

Thank you for these. The loss of water from the paper was my hunch too, but a completely untested one. However, I DO see the expected print colour variations I'd expect for the Malde-Ware process when I pre-humidify the paper at various, controlled levels. I guess the only real test is side-by-side comparisons of fast and slow UV sources. Hmm - so maybe I will build a fast source.

The slow development is not a big deal for me providing there's isn't any other issue at play.

Robert



On Thu, 20 May 2021 at 16:07, Walker Blackwell <forums@...> wrote:


On May 20, 2021, at 10:42 AM, Karen Hymer, <karenhymer@...> wrote:

Clay- is this also true (higher contrast with longer exposures) when exposing polymer plates?
Karen

Clay can correct me I’m sure, but I think polymers a fairly linear hardening (at least in my experience), and it’s also relatively short exposure (on the order of 1/3rd the amount of light is needed). 

Longer exposure for POP is due to increasing lack of moisture in the paper over longer exposure times I believe (a hunch!) . . . I’ve been wanting to play around with duel wave-length LEDs in order to add some contrast control during the exposure but the cost of metal for this R&D work would be extreme . . .

Older lights that are failing can be a big issue re: POP though . . . we saw a major increase in contrast with bad LEDs and super long exposure times. The benefit is that you can use much thinner negatives. But the time wasted was a lot.

Best regards,
Walker




Karen Hymer
Director
Light Art Space
Silver City, NM

On May 20, 2021, at 8:32 AM, Dr Edward Draper, <platinumprinz@...> wrote:

Brevity excused




On 20 May 2021, at 15:29, Robert Poole <r.poole@...> wrote:

Thanks Clay

Makes sense! This is the same explanation I think for increased contrast when giving traditional B/W films like FP4+  long exposures (several seconds). You’ll get higher contrast unless you contract development.

I’d like to hear other POVs too.

Robert

; please excuse brevity.



On 20 May 2021, at 15:16, Clay Harmon <w.clay.harmon@...> wrote:

The only downside I can think of for longer print exposures is they will create a higher contrast print. The old trick of exposing POP and salt prints in open shade to goose the contrast is an example of this. 

The reason, or at least what I have always theorized, is that low sensitivity processes have exposure thresholds that they much reach to initiate the  photochemical reactions. This means that shadow areas of the negative reach the threshold sooner and begin the photochemical reaction while the dense highlight areas of the negative are still below the threshold to begin the reaction. I’d be interested to hear from the real chemists in this group if I am on the right track here.

It’s a real measurable phenomenon though.

Clay

On 2021-05-20, at 04:54 :38, Robert Poole <r.poole@...> wrote:

This is a really useful thread for me as I've been musing over making a UV source for my iron-based printing (Pt, Pd, Au). 

I currently use a lab-style Transilluminator as used by molecular biologists (for example) for viewing nucleic acids and proteins on gels. My source is a UVP PLUS from Analyticajena with an electronic ballast and 25W tubes. It states that there are 4 tubes of each wavelength, 302 and 365 nm. The beauty is that I didn't have to make it (!) but it covers only 8x10 safely and my exposure times are typically 10-20 min.

So my question is: is there any downside or upside to long exposures? Does it matter (except for impatience on  my part). The only down I can imagine is that in the printing-out processes, the water retention in the paper will decline in very long exposures (perhaps?).

Thanks for any comments.

Robert



On Thu, 20 May 2021 at 02:43, Peter McDonald <pmviewcam@...> wrote:
Just built a new LED lightbox myself. I used 395-405nm  strips, 10 metres to cover 20x24. My testing showed that the LEDs were slower than my black light tubes and they were also a bright purple, going well into visible light.

I'm currently testing a small 365nm LED panel from Amazon (~AUD$60) which is giving a much quicker exposure time. The panel emits a weak white light, which is appropriate for wavelengths at that frequency. I will probably be replacing my current LEDs with the 365nm. They are much more expensive than the 395-405nm.

Cheers, Peter.




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