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*To*: BOOK_ARTS-L@xxxxxxxxxxxxxxxx*Subject*: Re: [BKARTS] percent solutions? mc, wheat, gelatin*From*: Audrey Hollinger <audreyh@xxxxxxxxxxx>*Date*: Fri, 18 Mar 2005 07:45:44 -0500*Message-id*: <887691AAF56A5C4A803F6850D35C089D43AD28@cerveau.thoughts.thinkage.ca>*Reply-to*: Book_Arts-L <BOOK_ARTS-L@xxxxxxxxxxxxxxxx>*Thread-index*: AcUq+StLqFeinlRaT9mtSIqz8viGSwAu3v8g*Thread-topic*: [BKARTS] percent solutions? mc, wheat, gelatin

Amy, Tablespoon-per-cup formulas can be scaled too! One tablespoon is 1/16 of a cup, so a formula calling for, say 1 tbsp/cup is 6.25% (1/16 or 100%) V/V. Now I will point out that this is only an approximation, and one that gets worse for higher percentages, since % V/V really means percentage of solute within the finished solution, whereas the formulas are usually given as amount of solute as a percentage of the (pure) solvent. Few recipes encountered in paper and book arts are of the form "mix powder with [less than the full amount of water], then top up with more water to [some specific volume]." More concretely, the above formula likely produces more than a cup of finished solution, so the actual V/V percentage would be less than 6.25% To convert from V/V formulas to W/V, you need to know the bulk density of the powder. Sometimes this is listed on a specifications sheet, and sometimes on the MSDS. Lacking either, I have found that assuming a bulk density of 1 g/cm3 is close enough. The only powders in our shop that are far from this are titanium dioxide and iron oxide based pigments. Does either of these approximations matter? Probably not. Most recipes have plenty of leeway in them, often ending with a recommendation to add extra water to suit. Differences in the water quality (e.g. mineral content) can have dramatic effects on the viscosities of these solutions, and individual recipes vary from one to another by more than the error in these approximations. As well, other technical changes in the usage of the solutions can adjust for varying solution strengths, for example by adjusting the temperature at which the solution is used. Unfortunately this general lack of technical rigour means that each artist must collect their own set of custom-tweaked favourite recipes by trial and error. -Kevin Martin the Papertrail *********************************************** The Bonefolder: an e-journal for the bookbinder and book artist For all your subscription questions, go to the Book_Arts-L FAQ and Archive. Both at: <http://www.philobiblon.com> ***********************************************

**Follow-Ups**:**Re: [BKARTS] percent solutions? mc, wheat, gelatin***From:*Norman Shapiro

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