Formulas- Grains or Grams

<p>When reading formulas, I frequently see the abbreviation <strong>g</strong>. I can't tell if this is grains or grams. For example:</p>

 

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<p>Distilled Water (125 degrees F) . . . . . . . 750 ml<br />Metol . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 <strong>g</strong><br /> Sodium Sulfite (Anhydrous) . . . . . . . . . . 100 <strong>g</strong><br />Cold Water to make . . . . . . . . . . . . . . . . . . 1 ltr</p>

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<p>Is that 7.5 <em>grams</em> or <em>grains</em> of Metol?</p>

<p><em>(note that my question is not limited to this recipe but to the notation frequently used in dark room formulas)</em><br>

<em> </em><br>

Thank you!<em><br /></em></p>

<p>It is confusing, as apothecaries often used both. My experience has been (in the USA) that grams have generally been abbreviated "g", while grains have been abbreviated "gr". Some of that also seems to depend on the time the formulas were put to paper. I used to have some pharmacology formula books from the early 1900s which didn't do a good job of differentiating, and one just needed to use common sense of proportionality to determine what was intended.</p>

<p>I'd think that the fact that the water measurements are in liters/milliliters suggests that we're talking grams here.</p>

<p>Where did you get the formula? - that and its date would be additional pushes in whatever direction. Information on what it is supposed to make would also be helpful, since then you could check it against other formulae.</p>

<p>Agfa formulae for things like Agfa 12 call for about 8 grams of metol..., so ...</p>

<p>The formula is D-23 from the Kodak "Processing Chemicals and Forumlas" book.<br>

<br />Yes it is grams. It is spelled out.<br>

The formula is also offered in US units, where it is 24 ounces water, 1/4 ounce Elon, 3oz plus 145 grains Sodium Sulfite, dessicated, and cold water to make 32 ounces.<br>

(You are supposed to know that liquids are in fluid ounces and solids in avoirdupois ounces.)<br>

<br />Wikipedia indicates that the official symbol for grains is gr, and for grams, g.</p>

 

<p>I suppose I should have recognized it, though I long ago standardized on D-76. Photographers' Formulary sell the chemicals in a kit:</p>

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<p>Formulary Film Developer 23 is a metol-based semi-compensating film developer similar to Kodak D-23. The developer produces negatives with low to medium contrast. Developer 23 is a favorite of Zone System users.</p>

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<p>http://stores.photoformulary.com/film-developer-23/ </p>

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<p>"Where did you get the formula?" - JDM</p>

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<p>I just picked it at random from this page: http://unblinkingeye.com/Articles/Developers/Formulas/formulas.html</p>

<p>It's good to know there is a standard abbreviation. I didn't know that.</p>

<p>I found another formula for a Metol developer, noted by a Flickr member, that calls for 50g of Metol. That's quite a bit more than the 7.5g in D-23! I have emailed the Flickr member to clarify their measure.</p>

<p>Grams/Grains... it doesn't take much to spell them out for the sake of clarity.</p>

<p>1g = 15.4234gr</p>

<p>I use a reloading scale (grains) for my very small measures as when you get into amounts such as 0.2g and then perhaps less in partial, test batches, measuring in grains is much easier to be repeatable and accurate. Most digital scales (outside of extremely high priced units) are not accurate at their load cell extremes. If you must measure small quantities, you will get more consistent and accurate results if you first tare a pre-load such as 50g or so, then weigh the small quantity.</p>

<p>My recipes are held in spreadsheets and the smaller quantities are also stated in grain equivalents for use on the reloading scale. These scales are quite affordable, especially used.</p>

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<p>50g of Metol</p>

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<p>But what is important there is how much water and other fluids are also added. If you're making a decaliter of developer, then you would need a lot of Metol.</p>

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<p>"But what is important there is how much water and other fluids are also added. If you're making a decaliter of developer, then you would need a lot of Metol." - JDM</p>

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<p>Excellent point! It's 50g of Metol per liter of water. What I failed to compare were the dilutions of the Metol-based developers. This working solution is highly concentrated compared to others. With this in mind, 50g/liter makes sense. I guess Part A will be a slurry. ;-)</p>

 

<blockquote>

<p>"I use a reloading scale (grains) for my very small measures as when you get into amounts such as 0.2g and then perhaps less in partial, test batches, measuring in grains is much easier to be repeatable and accurate." - Craig</p>

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<p>I use a small digital scale that I purchased some time ago from a reloading supply outfit. I use mine for measuring loose leaf Japanese tea, specifically gyokuro. I can eyeball virtually every tea on the planet, but gyokuro is unforgiving to steep in the small volumes used. I'm using a Jennings scale. It's one of the pocketable clamshell models with a 50 gram capacity. I have another scale for larger weights. Do you reckon the Jennings is accurate enough for grains?</p>

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<p>Do you reckon the Jennings is accurate enough for grains?</p>

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<p>The easy way to tell is get a check weight set. I have a Lyman set I use with my reloading scales. I use it to check my scales before and after each loading session (I am very attached to my fingers, hand, eyes, etc.). </p>

<p>Here is a link: http://www.amazon.com/Lyman-Reloading-Scale-Weight-Check/dp/B000N8LMFG/ref=sr_1_1?ie=UTF8&qid=1412276702&sr=8-1&keywords=lyman+check+weight</p>

<p> </p>