Litmus Blue & Red PAPER

[Labbie]

I have found a lot of Litmus Blue paper, but it has gone a Purple colour. Can it be restored to Blue in any way?????????

The Litmus Red is pink, but I have had no comments on it.

[Slartibartfast]

I've lightly sprayed individual sheets with a pump pack filled with distilled water I knew was pH7.0 to bring them back but never a booklet. Soaking would make it just run off. Does it matter what the start colour is? Try some good blue & one of your purple in the same solution and see what the outcome is.

[Robb]

Hi All,

Just be careful, most Red and Blue Litmus Paper are doped with a single indicator, where it is only sensitive to either Acidic or Alkaline Environments.

Just out of Curiousity and although similar in topic structure, I don't agree with the term "Basic" or "Basic Solution" -hmmmm..

Cheers,

Robb.....

[Whspa]

I'm sure this topic has surfaced here before, because it gave me this idea:
I store the blue litmus paper in a sealed glass jar containing a few drops of ammonia.
I use a piece of gauze mat to hold the litmus paper over the ammonia without touching it and it has returned to a lovely blue colour. The jar is labelled "Blue Litmus Paper Stored Over Ammonia" with the appropriate risk and safety data.

Carol

[Ian]

I know that this will go against what Robb has said, but we used to make "Striped" litmus paper by dipping a single piece of paper into acid say about 3cm, then alkali for about 2.5cm then acid for about 2cm then alkali 1.5cm, etc, etc. That has always made me believe that if you wanted it blue, just dip in NaOH and let it dry. If you want red, dip in HCl and let it dry. Mind you, I would not do that if there was any GREAT need for accuracy (eg senior titrations, etc) but then again, I would probably not be using litmus if I needed great accuracy, either.

regards
Ian

[Lyn]

The topic of litmus paper was covered to some extent back in Sept 2007. Just type litmus paper into the search section and check out the suggestions.
Lyn.

[Labbie]

Opps, sorry, still I was'nt the only one to forget.

Sorry folks

[Ocean Breeze]

Hi Sue, I just expose mine to a weak base, whether thats ammonia or a weak spray of Na OH.
when dried I store in an airtight jar, and it last a long time

[Ocean Breeze]

Theres another thread about turning existing litmus paper back to colours(or changing the colour for that matter)

I f you are anything like me, you have lots of stored boxes of faded blue and red litmus paper. Ones that you bought in bulk, but hasnt survived the of time.
Shame to throw out, but too faded to use effectively.

I thought I would share with you my little recipes


Blue Litmus
Make up a soln of a few litmus granules, dissolved in a small amt water.
Use town tap water to make blue soln. If you are on tank, or use distilled/de-ionised, it may be slightly acidic...so add 1 drop of VERY WEAK Na OH. it should turn blue .
Dip either the old faded swatches of paper..whole...into the soln. Allow them to draw up the soln so that its an even cover.
Or if starting from scratch to make your own, use either filter paper, or chromatography paper.
Soak while whole, and later when dry , cut it into desired sized pieces.(Otherwise you will end up with a terrible job separating later)

Red Litmus
Exactly the same as method above, but use dilute H Cl to turn the soln red.

When nicely soaked, using gloves (or method of choice, squeezing, rolling with pressure etc), squeeze to remove excess of the litmus soln. Place in a warm oven to dry, or use a fresh dessicator.( even in a warm spot, near a fan etc.)

When dry, seal each colour separately in a sealed container.

If anyone does it differently, would love to know.

[Ocean Breeze]

Nope made a mistake.
This IS the thread for litmus!

Forgot to add. I have fan in the prep room. Usually, I tie the wet booklets to a thread, then tie the thread to the fan, so that it is free to swing in the 'breeze'. Takes no time at all to dry out.(The quicker the blue is dried, the less likely it is to 'fade' to red...since we live in an acid world...)

[judygee]

Dear All - Some advise please - I have blue litmus paper that has been kicking around for some time and it has lost its colour, any suggestions as to restoring it to it's former glorious blue? Would drying it help? Looking forward to a reply. Cheers. Judy

[me]

Put a few drops of ammonia on a cotton ball in a container with the old litmus paper and it will be like new in no time.

[smiley]

Right on! I have the little booklets of blue litmus paper standing in a vial or a cup or something, which is inside a jar, and cotton balls packed around the base of the vial. Then I drop ammonia onto the cotton balls, and close the jar lid. I also do the same with red litmus, using vinegar. That way the papers themselves stay dry, but the "atmospheric ammonia" in the jar keeps the papers blue.