scale resolution for photo use?

[timeUnit]

I've been researching this issue for some time now, and can't get a straight answer...

I need a scale for measuring:

developing agents
wet plate chemistry
gum bichromate chemistry
cyanotype chemistry
vdb chemistry

All in "user amounts". Maybe 1 or 2 litres of developer or wet plate liquids, etc.

Do I need 0.01 or 0.1 gram accuracy/readability?

And by that I mean, does it actually matter for the results? Or is a 0.01 gram budget scale just false economy?

Thanks a million!

 

[donbga]

0.1 gram accuracy/readability?

0.1 gram accuracy is fine.

 

[Nick Zentena]

There can be a big difference between accuracy and readabilty. Just because a scale reads 0.1 doesn't mean it's accurate to 0.1.

I think a small/big setup makes the most sense. Two scales. One small and fairly accurate. One bigger and not needing the same amount of accuracy. The total cost will be much less then one good scale that does it all.

 

[GeorgesGiralt]

Hi Timeunit !
I only mix products for B&W classic process, so consider my comments accordingly.
I once used an Ohaus electronic scale with 0.1 g readability. I used it about 20 times and it died on me short after the end of the warranty period ( whatever you put on the platen, the indicated weight does not change until it reads 200g.... and stick to that value. The local Ohaus rep. told me it has to change the measuring sensor, but as the scale was sealed, it will be better change the scale... Grrr)
So i've bought a Chinese made copy of the Ohaus Triple Beam, still with 0.1 readability but with 2.6 kg max capacity and I am _really_ happy with it ! Convenient to use, no batteries (meaning they won't die during storage between two sessions) and enough precision for all products except Phenidone (which you will have to weight using a percentage solution anyway)and enough capacity to weight carbonate for paper dev. when planning to mix 5 liters...
Definitely the scale to own.

 

[GeorgesGiralt]

I forgot;
A friend of mine had bought a used laboratory scale (one under a glass and highly precise) for a song at a used lab material shop because the scale did not have the accuracy stamp on it. It has expired and, given it was an old model, was not worth the money to have it renewed...
So if you go the high precision route, this may be a lead to follow...

 

[GeorgesGiralt]

"There can be a big difference between accuracy and readabilty"
Yes, but accuracy can be checked quite easilly using known masses.
A box of wheights is not expensive and using new cions is very good. For example the Euro coins have weight precise at the tenth of a gram, in order to defeat conterfeit cions in vending machines. Try the coins you've in your pocket, and look at the Government offices for official weights. Get new ones and you've quite a good standard to check your scale.
Mine is accurate and repetability (which, IMHO is more important than pure accuracy)

 

[timeUnit]

Nick,
can you really rely on a cheap <50 g x 0.01 g scale? Or is it false economy? I'm in Sweden as you can see, and as usual the market is extremely small -- and the prices are high. Importing from the US seems to introduce prohibitive shipping/VAT costs.

I'm leaning towards a < 150 USD 0.05 scale, something like this:
http://www.vetek.se/Shop/Arts/Detail.aspx?artID=1012

 

[Nick Zentena]

Like George said you get a calibration weight or use coins. Mine works fine. It's actually 100 or 200 grams top weight.

 

[timeUnit]

I went ahead with the 250 gram x 0.05 gram scale, and a 100 g calibration weight.

Thanks for the tips on weighing coins for calibration/reference. One could probably use them to check linearity.

 

[GeorgesGiralt]

Hi TimeUnit !
If you're in Europe, have a look at http://www.auxilab.es they sold me my Ohaus copy are friendly, and being into Euro Land, won't cost you an arm and a leg in VAT+Duty....
Hope this helps

 

[Jerevan]

I found my Ohaus triple beam on the local auction site (Tradera). Works fine for me.