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> Sodium Hydroxide |
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#1
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Sodium Hydroxide
I am planning on making a Thiocarbamide toner to a recipe I have in one of my books (also in an old post here). I need sodium hydroxide which is the proper name for Caustic Soda. Can I use one of the readily available packages of this chemical, or should I be looking for a particular quality? Some versions available online are labelled 'pharmaceutical', or 'lab' grade. Thanks for any advice,
Alex. |
#2
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I recently purchased 500g of Sodium Hydroxide from Boots the chemist. The label states 98% purity which is as good as lab grade from Sigma Aldrich and less than tenth the price. Works just fine for lith developers, which is what I got it for,
For most photographic purposes, high purity analytical grades are not required. |
#3
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Quote:
Many thanks, Terry S |
#4
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Thanks, Paul. That sounds ideal. Will go to Boots tomorow.
Alex |
#5
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I bought NaOH as a 10% solution which is fine as a solution for thiocarbamide toners.
I found the bleacher recipes quite strong. Dilute further for better control of highlights. Lars |
#6
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I am finding it increasingly difficult to get raw chemicals from chemical suppliers as opposed to photo supplies dealers. Many will now not sell to private individuals. Certainly you will struggle to get either potassium or sodium dichromate as apparently it is now illegal to sell these to the general public.
I ran out of sodium hydroxide when I wanted to make some thiourea toner and went to my local hardware store and bought caustic soda at a very reasonable price. To my surprise it worked very well. Apropos Sigma Aldrich they agreed to send me a statement of use form so I could set up an account with them but they never bothered. |
#7
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Potassium/Ammonium Dichromates are regularly listed on ebay along with many other "restricted" chemicals - More often than not, smaller quantities will be sent out to you via Royal Mail
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#8
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As I'm just getting back into trying toning again, I thought that I'd resurrect this thread.
I bleached some strips of photographs for varying amounts of time yesterday, for which I've carefully followed a much printed 80% thiourea and 20% sodium hydroxide mix. In the pictures and written descriptions, there is definitely supposed to be a yellow range of tones. Whatever the length of time that I've left bits in the bleach for, I'm getting a definite warm and light sepia brown, on various RC and FB papers tried. Reading the information, this warm brown / light sepia, should be at the other end of the scale, when using a thiourea @ 20% and sodium hydroxide at 80% mix. All solutions have been quite diluted, as stated, to make up a litre of working solution of the two chemicals. I'm going to try some full size prints this afternoon regardless, but I wondered if anyone else has done some of this type of toning and may have any comments or tips, that may be of help to me? Just browsing, the picture on this site is the sort of tone that I was hoping to get: https://www.moersch-photochemie.de/c...en/113/lang:en Terry S |
#9
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Btw, photographic grade chemicals are at best tech pure and any grade will basically do. For caustic soda, one of the cheapest sources is caustic lye 40%, used for cleaning drains.
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#10
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Terry
Controlling sepia toning is down to the ratio of thiourea to sodium hydroxide in the toning bath, and the depth of bleaching. For a proprietary brand of sepia toner I would start by diluting the bleach to a third of the suggested strength. For the toning bath, the ratio for a warm toned image is 5-1(thiourea to sodium hydroxide), a mid tone would be equal amounts of each (thiourea to sodium hydroxide), and for dark brown 1-5 (thiourea to sodium hydroxide). In practice, for a warm tone print, add 50mls of the thiourea concentrate and 10mls of the sodium hydroxide to 1 litre of water. I have found keeping the toning bath warm at around 25degrees helps with the depth and warmth of the tone. I would suggest the example you gave on Wolfgang Moersch’s site, has been bleached into the midtones and toned using a 5-1 mix. Warm toned papers such as MGWT will also give a greater response with sepia toning. If you are interested, there is a short article about sepia toning on my website, under the heading information. |
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