Cobalt chloride paper...

I know it turns a different colour due to humidity/presence of water, but I have a supply here that looks like it has a slight pinkesh tinge but I place it in the water and nothing happens?

Can such test papers 'go off' as it were?

The test papers are white also.
 
I know it turns a different colour due to humidity/presence of water, but I have a supply here that looks like it has a slight pinkesh tinge but I place it in the water and nothing happens?

Can such test papers 'go off' as it were?

The test papers are white also.

The papers go from blue to pink. Yours need drying out, they'll still work once you get the water out.
 
It must be absolutely dry - any pink means it is moist. I keep mine in the desiccator to make sure is is completely dry. I then place a few strips in a boiling tube sealed with a bung (which are also kept in the desiccator) for the teacher/students to use. That way there is no chance of it becoming moist whilst waiting to be used.
 
@Paul I picked up your reply which mentioned the strength of the paper (now deleted) and yes you are quite right that the amount of cobalt chloride is very much reduced these days - I thought because of the cost
 
Someone bought about 10 boxes each containing 12 books all were vary faint blue so I soaked them in fresh 2M cobalt chloride (in the fume cupboard), allowed them to dry then placed them in the desiccator - they are all a nice strong blue colour now.
 
Someone bought about 10 boxes each containing 12 books all were vary faint blue so I soaked them in fresh 2M cobalt chloride (in the fume cupboard), allowed them to dry then placed them in the desiccator - they are all a nice strong blue colour now.
I might try soaking it in the fume cupboard. As I mentioned before, one box the slips were just white, and I did not see any colour change when I used tap water on them!
 
I know it turns a different colour due to humidity/presence of water, but I have a supply here that looks like it has a slight pinkesh tinge but I place it in the water and nothing happens?

Can such test papers 'go off' as it were?

The test papers are white also.

I usualy just dry out the paper which has gone slightly pink on a low heat on top of the heated magnetic stirrer. As soon as they turn a nice blue colour I use a pair of tweezers to transfer them into a small screw top bottle. Then supply the teacher with tweezers to get one out of the bottle. They react very quickly so moisture from your hand will turn them pink again.
 
As discussed, here is inside our silica gel desiccator with the 'home made' cobalt chloride paper (old faded books re-vamped by dipping in strong solution then dried).

When required I use the dry boiling tube, place in a few strips of paper then seal with dry bung.

The sealed tube can be left out with the requested equipment indefinitely, knowing that the paper will still be dry and useable when the teacher gets round to running the experiment.
1604413575142.png
 
As discussed, here is inside our silica gel desiccator with the 'home made' cobalt chloride paper (old faded books re-vamped by dipping in strong solution then dried).

When required I use the dry boiling tube, place in a few strips of paper then seal with dry bung.

The sealed tube can be left out with the requested equipment indefinitely, knowing that the paper will still be dry and useable when the teacher gets round to running the experiment.
View attachment 5005
Do you store this desiccator in a flammable cupboard?
 
As discussed, here is inside our silica gel desiccator with the 'home made' cobalt chloride paper (old faded books re-vamped by dipping in strong solution then dried).

When required I use the dry boiling tube, place in a few strips of paper then seal with dry bung.

The sealed tube can be left out with the requested equipment indefinitely, knowing that the paper will still be dry and useable when the teacher gets round to running the experiment.
View attachment 5005
That's great - thank you so much for sharing!
 
As discussed, here is inside our silica gel desiccator with the 'home made' cobalt chloride paper (old faded books re-vamped by dipping in strong solution then dried).

When required I use the dry boiling tube, place in a few strips of paper then seal with dry bung.

The sealed tube can be left out with the requested equipment indefinitely, knowing that the paper will still be dry and useable when the teacher gets round to running the experiment.
View attachment 5005

I have packets of silica gel in the tubes as well, they come in some deliveries to keep them dry.
 

Techitude

COMMITTEE
I microwave ours :laughing:

I make the paper myself with chromatography paper soaked in cobalt chloride solution, left to dry then cut up.
 
Top