What type of scalegreenspun.com : LUSENET : B&W Photo - Printing & Finishing : One Thread
I'm needing to purchase a scale to measure chemicals. Since I won't be doing a tremendous amount I didn't want to necessarily purchase the most expensive. However, accuracy is so important with this, I thought I would check here to what others would recommend. Any suggestions? thanks carol
-- carol maurin (firstname.lastname@example.org), October 24, 2000
What do you think about checking postal scales at an office supply store? May not be accurate enough, but probably cheaper than a bona fide chemist's scale.
-- Paul Swenson (email@example.com), October 24, 2000.
Traditional balances have gone the way of the dodo, but you might check auction sites and surplus scientific equipment dealers for what's known as a "Harvard Trip Balance". Lots of the ones made by Ohaus are great for photo use. If you get a dual pan type, you'll also need a set of weights. The single pan type has its own built in weights. Expect to resolve 0.1 gram if everything is working right. You can also get some nice digital scales now for $100 and up. Check with Daigger discount lab supplies at www.daigger.com and look for something like their Acculab HX1211A or B. Also, the Ohaus HX15700M. These are both under $200, read .1g and have a maximum capacity of about 400g. Higher capacity is nice, but the price goes up a bit.
-- Conrad Hoffman (firstname.lastname@example.org), October 24, 2000.
If you're buying new, an electronic balance is definitely the answer. I've just looked a couple up in a trade catalogue. One weighs up to 200gm in 0.1gm resolution, the other does 2Kgm in 1gm steps. Both were priced around B#80 UK ($120 US).
Check your requirements carefully before you buy. The resolution is more important than the maximum capacity, you can always weigh larger quantities in 2 or 3 lots.
As far as old mechanical balances go, the most convenient types are what are known as chain balances. These allow you to add a small amount of weight to the pan, without messing about with milligram sized bits of aluminium. BTW, if you do end up with a mechanical balance and brass weights, please use a pair of forceps (or rubber gloves) to handle the weights. If you don't, the weights will get so corroded that they'll quickly lose any accuracy they might have had.
-- Pete Andrews (email@example.com), October 25, 2000.
My typical "low budget" alternative: Unless you are mixing a lot of different formulas or really need accuracy more than one-tenth of a gram, you might just buy yourself a copy of "The Darkroom Cookbook" by Steve Anchell and use the spoon conversions in the back of the book. (Some chemicals even measure more accurately this way since the absorb or lose water with prolonged storage and therefore change weight.) I've converted my few favorite formulas to spoon formulas, and get good, consistant results. This is a viable alternative to scales, (and much quicker, I might add!) for formulas that are not critical and do not contain ingredients that have to be measured in very small amounts, (e.g. Phenidone) or to great accuracy. It's possible that some of the proportions are off by a small percentage, but usually this makes no appreciable difference, especially if you are consistant. It's similar to the difference you would get baking a cake with a volume amount or weighed amount of flour, sugar, etc. The cake comes out both ways.
If you do find you need a scales, just about any of them that read to 0.1 gram will be accurate enough for everything except the few chemicals like Phenidone which are used in very small amounts and require scales with greater accuracy. For this, Anchell in his book recommends the Acculab VI-200 which is accurate to 0.01 grams. I'm sure there are many others as well. I've even heard of people using a powder scale, (used for reloading cartriges), but then you have to convert to and from grains all the time.
-- Doremus Scudder (ScudderLandreth@compuserve.com), October 25, 2000.
If you want to buy new, check out www.balances.com
Best is to buy used. I picked up an Ohaus mechanical Dial-O-Gram 310. This uses a dail to set the lowest digits and sliding weights for the high digits. Ohaus will completely refurbish this model for something like $59, whatever it takes.
For used check eBay and various other sources.
As someone else pointed out, resolution is more important than capacity. At LEAST 0.1 gram, and preferably 0.01 gram. A capacity of 200 grams is enough.
-- Terry Carraway (TCarraway@compuserve.com), October 25, 2000.
I bought an electronic scale with the same idea: to mix my own chemicals. It hasn't been used much since for the chemicals I like to use the savings, if any, aren't much. In some cases it is more expensive to roll your own. So be sure you price the raw materials available in your area before you plunk down $$$.
-- Don Karon (firstname.lastname@example.org), October 25, 2000.
try this address www.balances.com/ashiba/mp500more.html I have been looking to replace my old scales and my research led me to this company. they recommend a scale for about $110 that they feel is better than several more expensive ones.
-- Ann CLancy (email@example.com), October 26, 2000.