Ive been using a spirit type thermometer but I find it difficult to read the small scale.
Can any tell me if this type of Weston thermometer is any good for chemical temperature measurement
Ive been using a spirit type thermometer but I find it difficult to read the small scale.
Can any tell me if this type of Weston thermometer is any good for chemical temperature measurement
In my experience dial thermometers are just not very accurate. If you can't read a conventional spirit thermometer you might consider getting a digital thermometer with and LCD and probe.
You can get a pretty good check on the accuracy by comparing it to another thermometer, such as a household mercury thermometer, an aquarium thermometer of a household/furnace thermometer. A few of these thermometers have a nut around the shaft to allow adjustment/correction.
But if it is too difficult to read, you can either buy one with a larger face or get a digital one with a bright readout.
The original Weston thermometers were specified as accurate to within 1/2 degree F. I've regularly used them. Now I have a thermocouple cooking thermometer that I could use to check the Weston thermometers, but the cooking thermometer was $180 US. I would not use it in chemistry, through, since I'm not sure of the metal it uses-I would check against cold and hot water.
Go to the hardware store or supermarket and buy a digital thermometer with a stainless steel stem, and water resistant construction (it will cost $10-$15)... Measures 10ths of a degree, responds quickly to changes, has a memory hold, reads F or C, and can even read temp differences in a thermocline in your solutions...
Good, cheap investment, and you can find contractor grade units for a little more, but still the same basic circuit...
Steve K
I find mine more than accurate enough for B&W use
My step-daughter asked me what I'd like for Fathers' Day a while ago. I responded "What would you get for the guy who has everything (hint: the answer is NOT penicillin)?" After thinking a bit and not wanting to break her bank account, I told her I could use another thermometer in the darkroom - a digital stem-type - as I have a couple of non-adjustable Weston dial-types with corrections taped on them (compared to my Kodak Process Thermometer). She found an acceptable one via Amazon ($10-15) that I blessed before she purchased - it reads F & C, responds quickly and holds the reading until turned off. And it also agrees with my Kodak one. Now I'm no longer like the guy with two watches who never knows what time it is, because the watches never agree. I don't plan to continue using the Westons.
A mercury or spirit thermometer is reliably accurate as long as it is unbroken and there is no gap in the mercury or spirit column. I've had dial darkroom thermometers become inaccurate. Sometimes this can be fixed, sometimes not. They are convenient and reliable enough if frequently checked against a good mercury or spirit thermometer.
Then you obviously need a third watch!Originally Posted by Jerry Bodine
I've used a lot of thermometers over time -- of various types. My most frequently used is a Weston-metallic-type, but with a bigger scale for easy reading. I have a great Unicolor Precision, mercury thermometer. More accurate, in terms of fine-tuned scale -- but who needs it? It is still VERY difficult to see the TINY mercury line!!!
No matter what thermometer you use -- it will be inaccurate. But the important thing is that it is consistent. So maybe it is 1 or 2 degrees high or low from reality. Who carses? If you run tests using your thermometer (NOT tests OF the themometer), then it will be OK. Just make sure you use the same thermometer. If a "process" says 90 degrees +/- 1/4 degree, run tests using your gear and get it right -- whatever the temperature readout is on your thermometer.
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