Fancy Schmancy Test Kit

Hi all,

I have two questions regarding the water test lab. The beaker bottles I have for mixing water with reagents are straight-sided glass jars with white plastic screw caps; the caps have a plastic foam liner inside. In case different manufacturers have different systems, mine is a JBL test lab.

1) I can get the jars clean but the caps are showing signs of (orange) crud inside the screw thread. Other than sticking my finger inside the cap (current, less than satisfactory, method) is there some way to clean these things? Preferably without damaging the foam liner, in case the foam liner serves a purpose. The kit did not come with any sort of brush for (or instructions on) cleaning the bottles.

2) The dropper bottles of reagents have child-proof caps. I HATE them. Has anyone found a way to remove the child-safety annoyance without damaging the bottles to the extent that they will leak? If there are legal/ethical issues regarding providing a public answer to this question, I invite response by PN.

Thanks in advance,

-Eva

G'day Eva,

I can only answer one of your questions:

1) I can get the jars clean but the caps are showing signs of (orange) crud inside the screw thread. Other than sticking my finger inside the cap (current, less than satisfactory, method) is there some way to clean these things? Preferably without damaging the foam liner, in case the foam liner serves a purpose. The kit did not come with any sort of brush for (or instructions on) cleaning the bottles.

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You can always wash the caps out with acetone, and then rinse the caps thoroughly with water from the tank or use deionised water.

I don't know about the safety caps. However, if you could post a picture, that would help. I'd imagine you can just distort the lid. Just guessing.

Jay.

Hi Jay!

Wouldn't acetone dissolve the plastic? Or at least the plastic foam? And be yet another chemical that would leave residue in the caps? Clarification: The fact that there is a visible residue in some of the caps makes me worry that there is invisible residue in the other caps.

-Eva

Try submerging the caps in vinegar (preferably distilled/white) for a while. I wouldn't use acetone either - it can dissolve some plastics, albeit slowly.

And any residual vinegar will not affect later testing?

I have washed NMR tubes and its plastic caps with acetone and have not noticed the caps dissolving. Not yet anyway. But it's standard procedure for the practical class, so I have no choice.

And any residual vinegar will not affect later testing?

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There won't be any if you give the caps a good rinse with water.

Jay.

Kal El said:

There won't be any if you give the caps a good rinse with water.

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But... I give the caps a good rinse with water and there is residue now.

I'm not being argumentative. I'm just being slow.

-Eva

Not your fault; I wasn't being clear enough.

I meant that if/when you give the caps a rinse with acetone or vinegar (preferably the latter. Just to be on the safe side) you will notice the orange crud dissolving away. Should you decide to use acetone, however, you can always dilute it with water, this way it will not be as concentrated. The same can be done with vinegar. Caution: Never add water to acid. Always add acid to water.

After the rinsing with acetone/vinegar, you will have to wash the caps out with water. The washing with water will have to be done thoroughly or you will have residual acetone/vinegar that will undoubtedly effect your readings.

Jay.

Which kind of brings me back to my original question: other than rubbing the inside of the cap with my finger under running water, is there some way to clean the caps?

-Eva

other than rubbing the inside of the cap with my finger under running water, is there some way to clean the caps?

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A cotton swab, perhaps?

Jay.

Child's toothbrush, steel wool, brillo pad, piece of sponge, wire bottle brush, q-tip, etc.

Figure out how the child proofing works and get rid of it. File off the internal ring, break the outer ring, etc. There are hundreds of methods for child proofing.

Kal El said:

I have washed NMR tubes and its plastic caps with acetone and have not noticed the caps dissolving.

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Plastic isn't all made equal.

Alright, I'll see if I can file off the thread. Now I just have to decide which of my children's toothbrush I'll use hehehe :evil:

Thanks,

-Eva

Eva,

I found that using a baby bottle nipple brush works best for me. Most baby bottle brush either have a nipple brush on the opposite end or come with a small nipple brush separate. Here is a picture of mine, I use the separate kind because the nipple brush is usually a bit more sturdy.
Hope this helps you.
Eve

blueberlin said:

And any residual vinegar will not affect later testing?

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Vinegar is perfectly water soluble so there shouldn't be any residue if you rinse it after the soak.

Kal El said:

I have washed NMR tubes and its plastic caps with acetone and have not noticed the caps dissolving.

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They will if left in it long enough (the acetone becomes coloured). Many chemists view the plastic caps as use once only.