D76 precipitate

<p>I just made up some fresh D76 from this recipe:<br />

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<td colspan="4" width="4000" bgcolor="#e0e2f4"><strong>KODAK Developer D-76</strong></td>

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<td></td>

<td>D-76 (developer)</td>

<td><br /></td>

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<td>metol</td>

<td>2.0g</td>

<td><br /></td>

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<td>hydroquinone</td>

<td>5.0g</td>

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<td>sodium sulfite (anhydrous)</td>

<td>100g</td>

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<td>borax (decahydrate)</td>

<td>2.0g</td>

<td><br /></td>

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<td>water to make</td>

<td>1 liter</td>

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<p>The water was deionised, and I boiled then cooled it to about 60 degrees to remove disolved air before adding the powdered ingredients.<br /> 24 hours after making it up, either the ingredients still haven't all disolved - or else the solution has dropped a small amount of very fine precipitate (maybe half a teaspoon's worth).<br /> I ran a test film with the solution - precipitate and all - at 1:1, and it looked fine (at least to my untrained eye.)</p>

<p>Should I worry?</p>

<p>It's been a few years since I last used D-76 but I remember the water had to be fairly hot, something like 125 degrees I think in order for it to dissolve properly.</p>

<p>Yes your water was too cold to dissolve the ingredients. Most likely it was the Borax ot Metol. that did not dissolve. Try to re warm the developer then remix. </p>

<p>Seems to me that D76 stock solution is a super-saturated solution, and that some precipitation will occur at lower temperatures....this does not affect its potency.</p>

<p>I take it from your spelling of "deionised" that you are referring to 60 C when you are talking about your water temperature. That would seem fine in terms of dissolution. <br /> Digital Truth (<a href="http://www.digitaltruth.com/data/kodak_d76.php">http://www.digitaltruth.com/data/kodak_d76.php</a> ) recommends adding the chemicals in a specific order, did you do it that way or all at once? <br /> Also, did you stir the mixture until everything was visibily dissolved? When mixing D-76, I have noticed that it does take quite a bit of stirring to get everything to completely dissolve.</p>

<p>If a powder developer is particularly annoying to prepare I use a magnetic mixer. If you mix by hand and have just a few specs in the liquid, just filter it out.</p>

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<p>I take it from your spelling of "deionised" that you are referring to 60 C when you are talking about your water temperature. That would seem fine in terms of dissolution. </p>

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<p>Correct ...</p>

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<p><br />Digital Truth (<a rel="nofollow" href="http://www.digitaltruth.com/data/kodak_d76.php" target="_blank">http://www.digitaltruth.com/data/kodak_d76.php</a> ) recommends adding the chemicals in a specific order, did you do it that way or all at once?</p>

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<p>In fact I did it all at once. Next time I'll try that order - good idea, thanks.</p>

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<p>Should I worry?</p>

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<p>Yes, you should. :-)<br /> Something is definitely wrong. You might get away with it once, but don't push your luck. ;-)</p>

<p> </p>

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<p>In fact I did it all at once.</p>

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<p>There's your problem, Alec. The chemicals MUST be dissolved in the precise order given in the formula. Metol won't dissolve in an alkaline solution, so it must always be added before the sulfite and the borax (actually, you can add just a tiny bit of sulfite first, to act as a preserver for the metol).<br /> You must make sure that each chemical is fully dissolved before going on to the next one.<br /> 60 degrees Centigrade is a bit on the high side. The recommended temperature is 50 degrees. 60 is still fine, but try not to go higher than that, because high temperatures accelerate the oxidation of the metol and the hydroquinone.</p>