New thermometer has gaps in the mercury

[Dave Krueger]

Ok, I know it's not mercury. I suspect it's blue alcohol. Anyway, I just got this new glass darkroom thermometer as a backup in case my other one breaks, but it has gaps in the colored material inside. Anyone know how to make it go back together? I tried shaking it, but no luck. Put it under cold and warm water and no luck there either.

-Dave

 

[raucousimages]

I heard dry ice is cold enough to fix it but I have never done it. I would hate you to break it. Can you return it?

 

[gainer]

Put it in the refrigerator's freezing compartment and see if it gets cold enough. The object is to shrink the indicator fluid enough that it is all inside the bulb. When it warms, there sholud be no bubbles in it. I doubt that you will break it, even if you use dry ice, but if the thermometer is designed to measure temperatures below freezing you may have to resort to dry ice. Did you try shaking it down with a swinging motion so as to provide centrifugal force?

 

[KenS]

Ok, I know it's not mercury. Anyway, I just got this new glass darkroom thermometer as a backup in case my other one breaks, but it has gaps in the colored material inside.

-Dave

Dave,
This column separation occurred in shipping....if you do not have ready acess to dry ice, might I suggest you hold the thermometer 'gently' between first finger and thumb. fold a piece of paper towel into about 4 and GENTLY drop or "tap" the bottom onto the folded paper towel on a wooden table (not the granite countertop)... from the height of about between one quarte and one half inch.

The gentle 'tapping' should eventually eliminate the gaps in the column... I have known it to take about an half hour of 'tapping'

...but remember.... you are NOT trying to drive the bottom of the thermometer through the table top. Continue until all the gaps have been eliminated. I have to do do this with both alcohol and mercury thermometers over about 50 years and have broken only one.

Ken

 

[gainer]

I think you can get the same or greater G-force by shaking as you may have seen nurses and doctors do before digital thermometers. Less danger of breaking unless you let go on the down swing.

 

[ooze]

Had the same problem once. I put the thermometer into hot water and eventually the parts merged close to the top of the scale. Took me only a few seconds.

 

[Pinholemaster]

I've always used a pan of hot water to raise the temperature enough to merge the fluid inside 'cause I never seem to have any dry ice around.

 

[matti]

Happened to two of my chaep spirits thermometers. I just wave them in the air like you would with a pen that has been standing upside down. Might be a good idea to check the accuracy afterwards.
/matti

 

[Bob F.]

There is almost certainly an expansion area at the top of the thermometer; just heat it up until the liquid has all expanded to the top - but don't over do it - and let it cool. Cooling it too fast will make it separate again...

Cheers, Bob.

 

[Steve Smith]

If you overheat it, it may burst out through the top. No need to ask how I know this!

Steve.

 

[Dave Krueger]

Freezing...

I put the thermometer in our freezer and the blue stuff went all the way down into the ball at the bottom. When I took it out of the freezer, the blue stuff crept back up with no gaps, but the reading is now about nine degrees too high. I will wait to see if it settles out to something more accurate or may repeat the exercise and leave it in the freezer longer. I was getting ready for work this morning so couldn't take time to fool with it much. I'm surprised a glass thermometer can be off by that much.

I assume that since I was able to get the blue stuff all the way down into the ball at the bottom, there would be no benefit to using dry ice. Is that correct?

If all else fails, I will just send it back to B&H and ask for a replacement. The thermometer is a Patterson.

-Dave

 

[Mike Té]

The gentle 'tapping' should eventually eliminate the gaps in the column... I have known it to take about an half hour of 'tapping'

Just last week I fixed my old Minox thermometer in this fashion. It took an hour of persistent tapping. It turns out to be an accurate thermometer, to my surprise.

Good luck.

 

[gainer]

How did you check the calibration? Distilled water with ice made from distilled water floating in it ought to be pretty close to 32 F or 0 C.

 

[Dave Krueger]

How did you check the calibration? Distilled water with ice made from distilled water floating in it ought to be pretty close to 32 F or 0 C.

Actually, I just checked it against the Kodak darkroom thermometer that I've been using for years. I don't how good the Kodak one is, but I know it's not nine degrees off.

Hmmm... I never thought of calibrating a thermometer like that. Unfortunately, the lowest reading on this one is 60F.

Anyway, the good news is that both thermometers were within a half degree of each other by the time I got home from work, so taking it cold was a good fix. It just apparently needed time to equalize to room temperature after taking it out of the refrigerator.

Thanks to all who responded with advice.

-Dave