Support our Sponsors, they keep FADU free:   AG Photographic   The Imaging Warehouse   Process Supplies   RH Designs   Second-hand Darkroom Supplies  

Notices

Go Back   Film and Darkroom User > Equipment > Darkroom

  ***   Click here for the FADU 2015/2014 Yearbooks   ***

Reply
 
Thread Tools Search this Thread Display Modes
  #11  
Old 23rd January 2020, 02:48 AM
Martin Aislabie's Avatar
Martin Aislabie Martin Aislabie is offline
Friend
 
Join Date: Nov 2008
Location: Stratford-upon-Avon, England
Posts: 2,081
Default

Quote:
Originally Posted by John King View Post
Pure guess work! The normal working temp is 38c so reasoning there was nothing to cook in the solutions I went up to 50-60 ish and there you have it. You will know if the vacuum has worked because when you unscrew the top there is a small inrush of air.

I have found that you MUST use glass bottles with a neoprene seal or it wont work. Cardboard ones will leak in a very short time. The developer was starting to discolour but it still worked very well so perhaps 6 months is the limit, 3-4 months will probably be safer.
Be careful of the temperature you warm your chemicals to.

Getting B&W chemicals to that temperature will probably kill them - they are designed to work around 20C and getting them too warm kills them.

Colour - designed to work at 38C - you are probably still within the "safe" window.

However, is you do stopper the bottle at 50C and allow it to cool to 20C - you only reduce the air volume/mass by 9% - is it really worth it ?

Martin
Reply With Quote
  #12  
Old 23rd January 2020, 08:26 AM
John King John King is online now
Friend
 
Join Date: Nov 2012
Location: County Durham
Posts: 3,319
Default

Quote:
Originally Posted by Martin Aislabie View Post
Be careful of the temperature you warm your chemicals to.

Getting B&W chemicals to that temperature will probably kill them - they are designed to work around 20C and getting them too warm kills them.

Colour - designed to work at 38C - you are probably still within the "safe" window.

However, is you do stopper the bottle at 50C and allow it to cool to 20C - you only reduce the air volume/mass by 9% - is it really worth it ?

Martin
Well clearly the proof is in the pudding with normal C41 negatives. The 9% will also remove a good percentage of the oxygen which is the killer. Heating the water will also remove any dissolved oxygen in the liquid. Heating the chemicals has had NO apparent effect. Where else would you find C41 diluted chemicals lasting 6 months and still being usable. Oh yes, a 30second blast in the microwave is cheaper than buying a gas spray.

Everything is also cooled to less than 20c, as my darkroom never gets up to those heady heights, even in the summer, normally it is around 15c. I always have to use back ground heating. Nor can I see how heating them up will 'kill' B&W chemicals, they are not organic. Can you say what you base this estimation on? I don't do the same treatment with B&W chemicals as they naturally last far longer. eg. ID11 or D76 when mixed will last for at least 1 year in glass screw top bottles. Rodinal will last far longer.

Last edited by John King; 23rd January 2020 at 08:35 AM.
Reply With Quote
  #13  
Old 23rd January 2020, 08:48 AM
Martin Rick Martin Rick is offline
Friend
 
Join Date: Jan 2017
Posts: 111
Default

Quote:
Originally Posted by John King View Post
Well clearly the proof is in the pudding with normal C41 negatives. The 9% will also remove a good percentage of the oxygen which is the killer. Heating the chemicals has had NO apparent effect. Heating the water will also remove any dissolved oxygen in the liquid as well and where else would you find C41 diluted chemicals lasting 6 months and still being usable.

It is also cooled to less than 20c, as my darkroom never gets up to those heady heights, even in the summer. Normally it is around 15c so. I always have to use back ground heat Nor can I see how heating them up will 'kill' B&W chemicals, they are not organic. Can you say what you base this estimation on? I don't do the same treatment with B&W chemicals as they naturally last far longer. eg. ID11 or D76 when mixed will last for at least 1 year in glass screw top bottles. Rodinal will last far longer.
Metol, hydroquinone, 4-aminophenol etc. are all organic chemicals.
Reply With Quote
  #14  
Old 23rd January 2020, 02:22 PM
maxwellmakosk maxwellmakosk is offline
Friend
 
Join Date: Nov 2018
Location: Hackney, London
Posts: 37
Default Vacuum Pump Chemical Preservation

I can confirm vacu-vin or similar wine pump stoppers work very well, they hold the seal and chemicals last much longer than any other system. I have also had success with wine bags in a cardboard box with a tap however it was a mess and while much cheaper at first they won't last forever and require much fuss when filling.

It is true they don't remove 100% of the air however breaking up a 5L kit into 5 1L glass bottles means whatever amount of air leftover will only affect the current bottle your processing with (if one shot) as long as you get through that liter within a week or so I cant imagine there would be any difference than if you somehow managed to remove ALL of the air from a 5L bottle as you used it.


Sent from my iPhone using Tapatalk

Last edited by maxwellmakosk; 23rd January 2020 at 02:33 PM.
Reply With Quote
  #15  
Old 23rd January 2020, 07:34 PM
Bob's Avatar
Bob Bob is offline
Administrator
 
Join Date: Aug 2008
Location: London(ish)
Posts: 2,746
Default

When mixing B&W chems from powder you generally use 40C water to dissolve the chemicals so I do not think heating to 50C will cause any issues.

Heating the chems will reduce the amount of dissolved air/oxygen in the liquid but will not remove it completely - if it did, tropical fish would all suffocate . I'm sure a google search would find out the actual percentages at various temperatures. This is why you need to reduce the number (or, the total length) of tropical fish over cold-water fish in aquariums of the same volume.

Nor am I convinced about the amount of air removed by small hand-pumps being worthwhile. There is a reason real vacuum pumps cost hundreds of pounds - generating a reasonable vacuum is difficult. I'm pretty sure the main advantage is due to decanting into smaller bottles with their attendant smaller air gap above. That, plus the use of the well-fitting, air-tight seal, will help considerably as many bottle seals are pretty poor, often made of permeable plastic or waxed card etc. Taking out perhaps 20% of the air (I would be amazed if it is more) does not hurt, but I doubt that it is the main contributor - the excellent seal it provides is my best guess at where the major advantage lies.

Regardless of all that, it certainly works but I would not rely on the "vacuum" alone. Once you have more than a few ccs of air, I think it's time to break out the Protectan/Argon/butane camping gas/butane lighter fuel/etc...
Reply With Quote
  #16  
Old 23rd January 2020, 08:37 PM
maxwellmakosk maxwellmakosk is offline
Friend
 
Join Date: Nov 2018
Location: Hackney, London
Posts: 37
Default Vacuum Pump Chemical Preservation

According to MLI Physics collection page 22 a vacu vin or similar can pull 400 mbar before the *click* which is quite substantial, almost half an atmosphere. Ill bet you could easily remove 50% of the air pulling past the click. Apparently people have broken wine bottles with them so I guess they can achieve the max pressure the glass can handle anyway. If going down the vacuum route it seems like a pretty good deal. Of course marbles, co2 is better if we're taking about amount of air removed.

I agree with Bob though I don't think even half an atmosphere is enough air to make a massive difference. But I imagine I helps create a good seal.


Sent from my iPhone using Tapatalk

Last edited by maxwellmakosk; 23rd January 2020 at 08:43 PM.
Reply With Quote
  #17  
Old 23rd January 2020, 09:41 PM
John King John King is online now
Friend
 
Join Date: Nov 2012
Location: County Durham
Posts: 3,319
Default

Quote:
Originally Posted by Martin Rick View Post
Metol, hydroquinone, 4-aminophenol etc. are all organic chemicals.
I bow to your chemical knowledge. However as I said the proof is in the pudding, 6 months after being diluted from stock, heated and it still works equally well as new.
I have no qualms about using the method again because I have actual physical proof that heating up to a reasonable temperature will work and work well, so why change it? It really is a 'no brainer'.

As I said about B&W I only mentioned film developer. With Ilford Multigrade I used to decant a 5 litre cannister into 9 x 500cc glass bottles and the remaining 500cc were then decanted into 5 x 100cc bottles which are a convenient quantity for an evenings work in the darkroom when diluted 1-9 or even up 1-13. No heat is use because the keeping qualities in a small full bottle are very good.

Last edited by John King; 23rd January 2020 at 09:46 PM.
Reply With Quote
  #18  
Old 23rd January 2020, 09:57 PM
Bob's Avatar
Bob Bob is offline
Administrator
 
Join Date: Aug 2008
Location: London(ish)
Posts: 2,746
Default

O-Level Chemistry to the rescue ... "Organic" just means "contains carbon". For example, engine oil is an organic compound (amongst other ingredients). No specific reason why an organic compound is susceptible to heat. As I mentioned, Ilford's ID-11 instructions are to mix at 40 degrees C so it is clearly safe at that temperature.
Reply With Quote
Reply
Support our Sponsors, they keep FADU free:   AG Photographic   The Imaging Warehouse   Process Supplies   RH Designs   Second-hand Darkroom Supplies  

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Chemical Storage-exended preservation. John King Chemical formulae 9 2nd June 2016 09:24 PM
Proseal 20x24" Vacuum Dry Mounting Press Tom Stanworth Auctions of Interest 0 27th March 2013 12:49 PM
20x24 PROSEAL Vacuum Press - A Real Bargain! Tom Stanworth Sale or Wanted 0 21st March 2013 05:28 PM
Chemical preservation John King Darkroom 4 8th December 2012 01:12 PM
vacuum easle GoodOldNorm Darkroom 5 9th March 2012 08:28 PM


All times are GMT. The time now is 09:06 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.