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Making solution for submersion based deacidification

CharlieCharlie Member, Administrator, Moderator, Game Master Posts: 6,298 admin
I've been reading that some folk might be attempting to wash/deacidify one of your own posters.  Last night Sven discussed book keepers spray a magnesium based deacidification product.  Based on my research I selected to use Calcium Hydroxide (CaOH) as a solution for deacidification.  I completely soak the poster and rinse out the reactants.  This is typically my first step outside of just getting the poster wet.

What you need to make it:

  • Scale (capable of measuring grams)
  • A 1 liter container
  • A 2 liter container
  • Distilled/deionized water
  • Stirrer
  • Calcium Hydroxide Powder

Measure out 2g of the powder on the scale and mix with 1 liter of deionized water.  Let it sit overnight, preferably 12 hours so the solution can reach equilibrium.  This one liter of solution is concentrated and will need to be diluted by another 1 liter of water. Any of the CaOH that doesn't mix with the water is basically still powder and settles at the bottom - I gently stirr up the top part of the solution but leave the particulates at the bottom.  Then I gently poor the mixed solution into the new container (leaving the remaining solid at the bottom) and then add the additional 1 liter of water.  After you mix the solution a bit more it is ready to use.

If you don't have fancy 1L containers you can also recycle...  I had to measure 1.5 grams to use these and then I'll poor them into the sprayer with equal parts deionized...


Untitled
That second mouse in the bowl of cream we call life...

Comments

  • jayn_jjayn_j Member, Singin Dancing Fool, Lobby Master Posts: 628 ✭✭✭ Daybiller
    Thanks.  Reading the earlier threads, I have gathered the water, blotter paper, weights, a proper pan sized for my lobbies.  The calcium hydroxide should be delivered tomorrow.  I have graduated bottles.  Guess I need to come up with a scale.  Does anyone have a formula for converting grams to tablespoons?  Those I have.

    After soaking in the CaOH2 solution, I need to rinse.  Is it OK to use tap water for this step, or do I need to come up with large amounts of distilled/de-ionized water and some sort of pump?  Not quite clear on the rinse.

    Back in the photography world, we simply kept a moderate flow of tap water to rinse the chemicals out.  My tap water comes a short distance from Lake Michigan and is pretty clean, but it is chlorine treated and fluoridated.
    - Jay -
    Curmudgeon in training 
  • EisenhowerEisenhower Member, Administrator, Moderator Posts: 4,038 admin
    I'd like to add that some of the solid cal hydroxide will make it into your bath one way or another-at least for me-so Ive begun to pour my mixed solution through a strainer with paper towels inside the strainer to catch the solids- works well and sounds a bit crude but Ive cut down on the white particles in my bath considerably. 

    As as for those used/empty liter bottles, nice tastes Charlie, esp the Bourbon!

    Here is a photo of my soaking tub after I pulled out a poster which had a lot of acids pushed out of the paper-hard to see, but the yellow in the water are the acids left behind-paper emerged in much better shape!

  • jayn_jjayn_j Member, Singin Dancing Fool, Lobby Master Posts: 628 ✭✭✭ Daybiller
    Reading your post, it looks like you are saturating the solution at room temperature and then diluting it 2:1.
    I am thinking I could slowly add the CaOH2 while stirring, a tablespoon at a time until there was a small amount left on the bottom, showing saturation.

    Thoughts?
    - Jay -
    Curmudgeon in training 
  • CharlieCharlie Member, Administrator, Moderator, Game Master Posts: 6,298 admin
     Let me take a picture to give you an idea.  In the end I don't think it is important as long as you don't poor the excess into the second liter of water.
    That second mouse in the bowl of cream we call life...
  • CharlieCharlie Member, Administrator, Moderator, Game Master Posts: 6,298 admin
    edited March 2017
    I use tap water to rinse and a final rinse with deionized... My water is high in CaCO3 so it actually adds some buffer if any of it gets deposited.
    Post edited by Charlie on
    That second mouse in the bowl of cream we call life...
  • CharlieCharlie Member, Administrator, Moderator, Game Master Posts: 6,298 admin
    I'd like to add that some of the solid cal hydroxide will make it into your bath one way or another-at least for me-so Ive begun to pour my mixed solution through a strainer with paper towels inside the strainer to catch the solids- works well and sounds a bit crude but Ive cut down on the white particles in my bath considerably. 

    As as for those used/empty liter bottles, nice tastes Charlie, esp the Bourbon!

    Here is a photo of my soaking tub after I pulled out a poster which had a lot of acids pushed out of the paper-hard to see, but the yellow in the water are the acids left behind-paper emerged in much better shape!

    I've never filtered mine but I don't leave it in a true bath like your tray.  I soak the poster between two Mylar and then wash.  So any of the particulates just get washed away.  
    That second mouse in the bowl of cream we call life...
  • CharlieCharlie Member, Administrator, Moderator, Game Master Posts: 6,298 admin
    edited March 2017

    jayn_j said:
    Reading your post, it looks like you are saturating the solution at room temperature and then diluting it 2:1.
    I am thinking I could slowly add the CaOH2 while stirring, a tablespoon at a time until there was a small amount left on the bottom, showing saturation.

    Thoughts?
    Just add and get rid of any that doesn't react... You probably don't have a pH reader but if you did all you would need to do is make sure the pH is not way above 9-10...
    Post edited by Charlie on
    That second mouse in the bowl of cream we call life...
  • jayn_jjayn_j Member, Singin Dancing Fool, Lobby Master Posts: 628 ✭✭✭ Daybiller
    Thanks.  Have strips as well.
    - Jay -
    Curmudgeon in training 
  • SvenSven Member Posts: 2,093 ✭✭✭✭ Three-Sheeter
    Great insight! I actually thought there would be lesss chemicals to mix 
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