Recommendations for lab balances

dancqu · Aug 22, 2009

Tom Kershaw said:
... sealed controls and a stainless steel platform,
which seem appropriate for a darkroom environment
as occasional spills or splashes are almost inevitable.

Twixt the steel and material being weighed I place
a small paper plate and on top of that a weighing
paper. Chemicals never touch the platform.

My 200 gram Acculab has 0.01 gram resolution and
accuracy. The capacity is more than enough. Check
out their line. IIRC they have a 100 gram version
of the mentioned scale; about $100.

Don't forget the Weighing Papers. A 500 sheet box
will last a life time. They're reusable. Dan

Photo Engineer · Aug 22, 2009

Ian Grant said:
I used to use Sartorius balances, they weren't bad, I had a set that weighed to 4 decimal places - 0.0001 of a gram, I also bought two Mettler balances, they weighed to 5 decimal places, I paid about £3,000 for one set 20 years ago They paid for themselves quite quickly

Ian

With that kind of accuracy and paying themselves off so quickly, you must be a drug dealer.

No drug dealer could make that much unless he weighed out 0.0001 gram of drugs and the remainder up to 1 g of powdered whatever to bulk it up. That way all of his customers were assured of the same thing.

My Sartorius cost me $100 and weighs from 0.0001 g to 10 kg with tare. It has a built in level and a serial and parallel output for computer logging and alarming over/under. It can also do English and Imperial units, but then of course I never use them. Don't know why anyone ever came up with either. That oddball system. You guys could never count on your fingers and toes. Too many of you had odd numbers and had to count in odd ways.

PE

jeffreyg · Aug 22, 2009

I have used a battery operated mail scale that I purchased in an office supply and tested it with lab weights of exact amounts it is perfectly accurate and will give weights in ounces or grams. It was not expensive.

gainer · Aug 22, 2009

Now if only you could afford chemicals that good!

fotch · Aug 22, 2009

As much as I like electronic gadgets, I went the mechanical route. No batteries, long life. Lower cost. For 3 used (like new) Ohaus scales, I paid less than $50 including shipping.

Triple Beam Balance Scale. Cap. 2610 g (Read: 0.1 g )
Trip Beam Balance Scale Cap. 2000 g (Read: 0.1 g)
CENT-O-GRAM Scale Cap. 310-311 g (Read: 0.01 g )

Since chemistry is somewhat new to me and I wasn't sure what I would need, I got the assortment.

Of course, if your using scales often, which many of you do, I can see a quality electronic scale is the way to go.

Kirk Keyes · Aug 23, 2009

Tom Kershaw said:
Do you have any experience with the Sartorius or Denver Instrument models?

Tom

I've not used a Denver Instruments scale, but I do have a Denver portable pH meter that I bought from eBay and I really like it.

From my experience, Mettler, Sartorious, and Ohaus made excellent scales.

Ian Grant · Aug 23, 2009

Photo Engineer said:
With that kind of accuracy and paying themselves off so quickly, you must be a drug dealer.

No drug dealer could make that much unless he weighed out 0.0001 gram of drugs and the remainder up to 1 g of powdered whatever to bulk it up. That way all of his customers were assured of the same thing.

PE

When you're testing around 60-100 samples a day @ roughly £7 a test (minimum - many were for 2 or more precious metals) then you recover the investments in equipment rather quickly.

In addition only 2 or 3 large clients had their samples back, all gold/silver from fire assay as well as solutions used for AA testing was recovered and in a year that metal alone would more than cover the costs of a set of analytical scales

Ian

Photo Engineer · Aug 23, 2009

Awww, you ignored my comment about fingers and toes.

PE

cmacd123 · Aug 23, 2009

The newer electronic scales are good value, and the one I use you can set it to turn off - or not- in one of the sub-menus. most of the other "features" can be enabled or defeated as well. The cheep scales do drift as they warm up, and can hum when they are left on, but it is hard to imagine geting a new mechnical scale that measures .01 g for 50 bucks.

(I am happy with my myweigh)

Ronald Moravec · Aug 24, 2009

Ohaus triple beam balance. Total accuracy is not important, but repeatability is when you are trying to measure small grams of metol. Anything will measure 500 gm of sodium sulfite with sufficient accuracy

Treat it well and it will last a lifetime. I am using an Ohaus my father in law used in med school or college in the 1930`s. I found it in his garage. Before that, a $10 cheapie I for in the late 1960`s. Both work ok.

Ideally a small scale for metol and hydroquinone and other small amounts and a larger one for sulfite and carbonite would be ideal, but totally unnecessary for photo use..

Anscojohn · Aug 24, 2009

I have an Ohaus powder scale I use for weighing charges of gun powder. It is calibrated to 1/10 of a grain. Cost about thirty-five bucks, iirc. For larger amounts, I have an Ohaus school balance scale bought at a flea market for five bucks. I have two sets of weights for it from one eight ounce to a pound. Two sets of weights because I misplaced the first set.Mostly I use them to check the weights thrown by my ss kitchen table spoons.

wogster · Aug 26, 2009

Photo Engineer said:
With that kind of accuracy and paying themselves off so quickly, you must be a drug dealer.

No drug dealer could make that much unless he weighed out 0.0001 gram of drugs and the remainder up to 1 g of powdered whatever to bulk it up. That way all of his customers were assured of the same thing.

My Sartorius cost me $100 and weighs from 0.0001 g to 10 kg with tare. It has a built in level and a serial and parallel output for computer logging and alarming over/under. It can also do English and Imperial units, but then of course I never use them. Don't know why anyone ever came up with either. That oddball system. You guys could never count on your fingers and toes. Too many of you had odd numbers and had to count in odd ways.

PE

I always wondered that myself, it often seems like they picked an arbitrary number between 3 and 99 for the next division. What really gets confusing is when you get a measurement like a Gallon, there are several different measurements called a gallon, and they are all different sizes..... A litre is a litre is a litre and converting to larger and smaller units just means shifting the decimal around.

Sirius Glass · Aug 26, 2009

wogster said:
I always wondered that myself, it often seems like they picked an arbitrary number between 3 and 99 for the next division. What really gets confusing is when you get a measurement like a Gallon, there are several different measurements called a gallon, and they are all different sizes..... A litre is a litre is a litre and converting to larger and smaller units just means shifting the decimal around.

The English system, probably the last of its ilke, was based on practical and convient measurements at that time [a carot was based on the weight of a carob seed]. It was not logical and changed according to what a king had for breakfast that day.

The French Revolution swept in the Metric System which the rest of the World greatfully adopted. But in the US, we are stubborn and will stick with our outdated system no matter how much the non-standardization [World wide standardization] costs us. So if you come here remember who many pecks in a bushel and how may feet in a furlong.

Steve

gainer · Aug 26, 2009

And that the definition of "snail's pace" is one furlong per fortnight.

Kirk Keyes · Aug 27, 2009

I once snuck the units furlong per fortnight into an SOP in place of cm/sec. Nobody noticed!

Photo Engineer · Aug 27, 2009

As an exercise in general physics we had to calculate the speed of light in furlongs per fortnight. We also had to convert horsepower into an old French unit which was roughly translated as "horse gas hours". It may have had something to do with the Methane emission of horses.

PE

Denis K · Aug 27, 2009

gainer said:
And that the definition of "snail's pace" is one furlong per fortnight.

For those with a bent for measuring in unusual units the following two wiki pages are an invaluable reference:

http://en.wikipedia.org/wiki/List_of_humorous_units_of_measurement

http://en.wikipedia.org/wiki/List_of_unusual_units_of_measurement

For example I often use a 7000000 beard-second camera.

Denis K

steven_e007 · Aug 27, 2009

Sirius Glass said:
...in the US, we are stubborn and will stick with our outdated system no matter how much the non-standardization [World wide standardization] costs us. So if you come here remember who many pecks in a bushel and how may feet in a furlong.

Steve

Being English I could cope with the Imperial system ("English", as the Americans call it. But stop blaming us, I say! )
I say could, except that Americans often mix metric and imperial together. MADNESS!!!!
How often have you seen grams per fluid ounce? Millilitres per gallon? Even ounces per litre? That is really insane!

I work for a German company that owns an American subsidery. I have to carry two sets of tools everywhere. I wouldn't mind if it was all imperial - but the gear is assembled in the US (all imperial) from things made in the far east (all metric). We're not just talking 1/2" spanners, either. Try finding a 17/64" Allen key in a hurry! Drives me nuts! (Imperial AND metric nuts!)

I seem to recall a few well known hicups due to 'mixing'. Didn't a multi billion pound mars explorer smash into the planets surface because the sofware designer was told to fire the retros at 300 metres and the engineers meant 300 feet, or something?

Complete, total madness I tell you!!!!!!
[/rant]

Anyway, to get back on topic, I found an ex-school chemistry lab balance in a flea market for a few quid. Very accurate, very precise, in a wood and glass case and all mechanical so no worries with batteries or spillage.

There is one on eBargunbay, too. No use unless you are in the UK, but a good example of what I mean. It will be interesting to see what it goes for. I suspect very little:

http://cgi.ebay.co.uk/Chemical-Bala...e_RL?hash=item3ca50900db&_trksid=p3286.c0.m14

sanking · Aug 27, 2009

steven_e007 said:
Being English I could cope with the Imperial system ("English", as the Americans call it. But stop blaming us, I say! )
I say could, except that Americans often mix metric and imperial together. MADNESS!!!!
How often have you seen grams per fluid ounce? Millilitres per gallon? Even ounces per litre? That is really insane!

http://cgi.ebay.co.uk/Chemical-Bala...e_RL?hash=item3ca50900db&_trksid=p3286.c0.m14

I mix metric and imperial systems all the time. For making carbon tissue I will often specify something like. "Pour 100 ml of solution on substrate of 150 square inches, at 65 degree F. This will leave a wet height of approximately 0.7mm. Sensitize at 60-65 degrees F.

It makes perfect sense to me?

Sandy King

Sirius Glass · Aug 27, 2009

steven_e007 said:
Being English I could cope with the Imperial system ("English", as the Americans call it. But stop blaming us, I say! )
I say could, except that Americans often mix metric and imperial together. MADNESS!!!!
How often have you seen grams per fluid ounce? Millilitres per gallon? Even ounces per litre? That is really insane!

I suppose like working on a British car and finding that the Imperial/English tools don't work and have to get out from under the car, clean up and drive all over town to find Wentworth tools?!?

Steve

Photo Engineer · Aug 27, 2009

At Kodak, the coating convention was to prepare a coating in milligrams / square foot!

PE

wogster · Aug 30, 2009

steven_e007 said:
Being English I could cope with the Imperial system ("English", as the Americans call it. But stop blaming us, I say! )
I say could, except that Americans often mix metric and imperial together. MADNESS!!!!
How often have you seen grams per fluid ounce? Millilitres per gallon? Even ounces per litre? That is really insane!
[/rant]

Believe it or not, in the UK as in Canada imperial units are defined in SI units, so a Gallon is defined as 4.54609 litres. This is also the case in the US where that gallon is only 3.785411784 litres. I expect that over time, the units will get rounded off to some degree, most liquids sold in US gallons outside the US use 3.8 litres for a gallon. Probably at a lower level, for example an ounce becomes 30ml rather then 29.573529563 as it is now.

The most confusing aspect of Imperial measure was that sometimes the same term (like ounce) was used in a number of different places, like liquid measure, dry measure and weight and don't seem to be related. Metric actually has these relationships, but uses different terms, for example a block of water 1cm x 1cm x 1cm is 1millilitre, and 1ml of water weighs 1g.

Sirius Glass · Aug 30, 2009

wogster said:
steven_e007 said:

Being English I could cope with the Imperial system ("English", as the Americans call it. But stop blaming us, I say! )
I say could, except that Americans often mix metric and imperial together. MADNESS!!!!
How often have you seen grams per fluid ounce? Millilitres per gallon? Even ounces per litre? That is really insane!
[/rant]

Click to expand...

The most confusing aspect of Imperial measure was that sometimes the same term (like ounce) was used in a number of different places, like liquid measure, dry measure and weight and don't seem to be related. Metric actually has these relationships, but uses different terms, for example a block of water 1cm x 1cm x 1cm is 1millilitre, and 1ml of water weighs 1g.

Other then the letters and the order of the letters, the three "ounce"s seems to have no relationship.

Steve

wogster · Aug 30, 2009

Sirius Glass said:
Other then the letters and the order of the letters, the three "ounce"s seems to have no relationship.

Steve

And the US fluid ounce is not related to the Imperial (liquid) ounce, so really there are 4, and this using the same term over and over in different places is what makes it confusing. You need to be oh so careful with the context.

pnance · Aug 31, 2009

The Cent-o-gram scale is a good recommendation. It will weight up to 311 g. with an accuracy to 0.01 g. The one I have (picked up in a flea market for $20) has been tested and repeats very well.

Recommendations for lab balances

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