Scales for weighing dry chems?

[Frank Lahorgue]

Many thanks to all of you -- I had no clue there were so many good solutions to one simple need. The combined experience of people on this forum is truly AWESOME.

[Craig Schroeder]

This thread on scales had me thinking of the fact that I hadn't thought of some basic, logical weighing methods until someone showed me:

When measuring dry chemicals, place the supply container, cover off, onto your scale (assuming digital), then tare. The scale will measure negative values as you remove material. This allows you to tap off your spoon on the receiving vessel and better account for clinging material and also helps to avoid mistakes of over-adding that can occur when trickling directly to the receiving vessel or spoon from the supply. You can't add any more than you take out of your supply source!

I also keep my recipes on spreadsheets and have the grain equivalents automatically calculated for the smaller amounts and use my beam balance powder scale for that duty.

[Nick_3536]

I tend to buy bigger amounts of dry chemicals. Using the method you describe wouldn't work that well for me. A big scale tends to not be that accurate. Removing 2 grams from a 2kg bottle tends to just be a rounding error.

[Craig Schroeder]

Good point, Nick. I decant to smaller, mid-sized containers, add a bag liner in the large containers to seal as well as possible and this makes the system I describe quite manageable. I work (my day job!) in a development lab and have simply adapted some of my company's daily work methods to my darkroom activities. I don't buy extreme sizes of much and even sodium sulfite and sodium carbonate in 5# tubs are about as big as I purchase. I don't like wrestling with that size container when measuring out batches, anyway. When I measure, say 10 grams and under, I trickle into my powder scale and convert to the grain equivalent. It's likely accuracy overkill but I feel better getting whatever variables controlled that are that easy! I use a few highly concentrated developers and I feel like it would be very easy to alter my consistency with even slight measurement errors.