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Frank Lahorgue
12-Sep-2005, 22:32
I've decided to try mixing some special developer using dry chemicals by weight, but I don't own suitable scales. Could someone guide me to a source for scales that won't slice up my film budget too badly?

Thanks

Tom Jones
12-Sep-2005, 22:48
Try searching for "Ohaus" on Ebay. Good scales. Lots of them around so they're not real expensive. The triple beam scales work great, and go to around 2.2kg max as I recall. Some others only go to around 300 gms. Just make sure the scales will cover the weight range you need.

Donald Qualls
12-Sep-2005, 23:29
Depending how much you need to weigh, Ohaus, RCBS and, IIRC, Lee also sell powder scales for reloading that will work very well for mixing chemicals; I have one I've had for about 20 years that will divide a gram into 154 equal parts (that is, it weighs to 1/10 grain), and will accommodate up to 500 grains, about 36 grams (there are models that will accept more weight, but they're rare; 500 grains is enough powder for an elephant gun). If you're making a liter of D-76, you'll have to weigh the sulfite in three increments -- but these scales sell, new, for well under $50; you might get one for $20 (or fifty cents at a yard sale, occasionally). Triple beam balances are great, but they're generally more expensive, and more delicate than a reloading scale, and won't do any better job within the smaller range.

Jeff Moore
13-Sep-2005, 02:47
Donald, would you mind specifying the brand name and model number of the scales you are describing. Sounds like this is exactly what I need. Thanks.

John Cook
13-Sep-2005, 05:21
I have a real nice postal balance beam scale I bought at the local office supply store in 1975. Seems very accurate. Probably worth about 25 cents at a tag sale these days.

But as I have never mixed my own chemicals, I have no idea of the weights involved. This unit is probably calculated in 1/2 ounces up to three pounds or so. That may be too heavy or too coarse for photography.

Ken Lee
13-Sep-2005, 06:57
I bought an Ohous CS 200. I don't remember where I got it, but it's quite nice, and runs on a simple battery. It's great.



Carl Weese (http://www.carlweese.com" target="_blank) told me he uses paper cupcake cups to hold the powder while measuring... great idea !



A quick Google search reveals a description and price here: http://www.discountscales.com/specs/ohaus/csspecs.htm (http://www.discountscales.com/specs/ohaus/csspecs.htm" target="_blank).



If you get one, be sure to remove the inner collar that protects the unit during shipping. I thought I got a lemon until I figured that one out.

Nick_3536
13-Sep-2005, 07:00
If you go to Ebay various sellers have gem scales. They are intended to weigh gems etc. They are cheap. Depending on the seller can be less then $20 but you know how Ebay goes. The only downside is they are limited to something like 250gram at most. Mine is limited to 100grams IIRC.

If you combine one of these with a cheap kitchen scale for the heavy stuff. You'll be all set. Heavy stuff doesn't need high accuracy. 1000 grams isn't much different from 995 grams. OTOH if you're weighing 1 gram you don't want 6 grams.

David A. Goldfarb
13-Sep-2005, 07:05
Lots of good prices at www.balances.com.

I have a small Toyo 250 pocket scale. It's very compact and has a capacity of 250 grams, which is enough for most developers. If you're going to mix your own fixer, then you'll want a scale with a capacity of at least 500 grams. If I need to measure more than 250 g occasionally, then I measure in two batches.

For small amounts, I just measure the chemical out onto a small slip of paper. For larger amounts, I use a plastic or paper drinking cup that I can discard afterward.

Jim Rhoades
13-Sep-2005, 07:18
The Ohaus, RCBS, Lee are the brand names. Go to any good guns & ammo store. These scales are very accurate. They have to be or you will blow yourself up. That's bad for business.

Matt Mengel
13-Sep-2005, 08:08
The cupcake papers are a great idea! I use basket coffee filters for the bigger amounts.
I have an Ohaus that was free. It works great.
Matt

Tracy Storer
13-Sep-2005, 08:38
I looked everywhere and couldn't find a good old basic triple beam balance. I don't remember who I called with my problem, but the advice was brilliant and hilarious="Dude, just go to any head-shop". An hour later I was back from Telegraph Ave. in Berkeley with a brand new Ohaus.
Tracy

ronald moravec
13-Sep-2005, 09:31
A nice electronic one is fine. You can spend as much as you like on a scale, but it is totally unnecessary. You need one that is repeatable, but necessarily perfect in accuracy. When you make up a developer and work out your times, you will automatically make up for slight inaccuracies. If you have 5 grams or 4.8 or 5.1 gr of metol in in a liter of D76. It does not matter as long as you mix it the same each time and you kept the chemicals fresh.

Figure how much solution you will make at a time and base the scale capacity required on the heaviest weight to weigh for that volumn. Sodium sulfite is usually the most heavy at 100 gm per liter. If you are making a gallon at a time, you can always weigh out 100 g four times.

Sulphite just being the preservative, you can actually weight it one time and go by volumn after that. The developing agents and acclerators are the critical components and the amounts used are much smaller.

I have an old $10.00 one I used for years without trouble and recently found an old pharmacy scale in a doctors garage. It looks like an antique with its cast iron base. It would fit in a 1900 drug store display. The D76 I make works the same as Kodak`s package mix, so you don`t need a $1000 balance enclosed in a glass box.

Metol will oxidise, so keep it in full small bottles. Cut down a small plastic spoon to remove the powder. Tape around the cap -bottle seal to make a perfect seal.

paulr
13-Sep-2005, 12:57
Acculab makes a nice range of electronic scales. I believe you can get them from Edmund Scientific.
Mine weighs up to 300g (enough for me most of the time). It's readable to .1 gram, which may be a nuissance if you need to measure a lot of tiny quantities (phenidone, etc.). If you're willing to pay more, there are plenty of scales that are readable to .01 gram. Or you can make percentage solutions for the really small stuff.

Nick_3536
13-Sep-2005, 13:20
For small amounts how small it reads only matters if it's accurate. Somebody was selling a scale that read 0.1 but was accurate to +/-0.5 grams. Not good if you need accuracy.

Donald Qualls
13-Sep-2005, 15:40
My reloading scale is an RCBS 5-10 model, but I've had it for between 20 and 25 years; I'm not sure the same model is available. Nearly identical scales were sold by Ohaus, RCBS, Lee, and possibly Speer and Hornady; if you do into any gun shop that sells reloading supplies (which is practically all of them other than pawn shops) and ask to see powder scales, they'll show you what you need.

No guarantee they're still cheaper than comparable "chemical" scales, but they used to run less than 1/3 the price.

chris_4622
13-Sep-2005, 16:21
http://saveonscales.com/index.html

Keith Pitman
13-Sep-2005, 20:14
Another good brand is Acculab. They can be found on eBay as well.

If you shop around, you can also find a decent gram scale at a cooking store, just make sure it has enought capacity.

Robert C. McColloch
13-Sep-2005, 22:36
Frank, I've found that in most cases, I do not feel the need for precise weighing of chemicals so I use a chart that has equavalent weight-volume conversion information. If you are interested, let me know and I'll make up a copy for you.

Wilbur Wong
14-Sep-2005, 10:07
Frank,

I use a "double beam and dial" O haus gram scale. It sells for 186 or so at McMaster-Carr http://www.mcmaster.com Might be available for less else where, and it has a tare weight ability (zero out your container from what you are weighing.) Other O haus models start just over $100.

These are accurate to 1/10 gram! Digital strain gauge models from kitchen suppliers I find to vary by just over a gram or gram and a half which is just fine in my kitchen and run $30 to $70. That's also pretty insignificant at a pound (453.5916xxx) but maybe significant in the 1/4 ounce range for a 25% error.

Nice to see you back from the Basque.

Wilbur Wong
14-Sep-2005, 10:16
A trick I used to use before I bought my O haus on small quantities was to measure maybe 4 times what I needed, pour it out on a piece of paper and split it in half twice with an index card. Effectively I thought this improved the accurace by a factor of 4. So this might help if your are measuring metol (if it all dissolves)

Frank Lahorgue
15-Sep-2005, 09:31
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
17-Sep-2005, 14:11
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
17-Sep-2005, 14:35
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
17-Sep-2005, 16:29
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.