The products

Samples, crystals and home chemistry

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pH test sample Which is the one case where the archetype is exactly right Fill it full and cap it Crystal growing So a wide straight jar beats a bottle And the closure has to be loose Home chemistry Science fair sample Label everything, including the boring ones Keep the quantities small References

A crystal grows in the vessel. The vessel is part of the result.

pH test sample

Water, soil slurry or a solution, collected and measured. The container must not change the sample, which rules out anything that leaches or adsorbs.

Which is the one case where the archetype is exactly right

"Reagent or sample", chemical resistance, narrow mouth, glass or HDPE, cold, thin, aqueous. A pH sample is precisely that and the shelf serves it.

Fill it full and cap it

Headspace lets carbon dioxide exchange and a water pH drifts. A sample bottle filled to the brim and sealed gives a reading closer to the source.

Crystal growing

A saturated solution left to evaporate, or a seed crystal suspended in one. The container is the growth chamber and its shape decides what the crystal can become.

So a wide straight jar beats a bottle

A crystal needs to be reachable and visible, and growing one in a narrow neck means breaking the container to get it out. 150 jars here and 21 glass straight sided.

And the closure has to be loose

Which is unusual in this catalog. Evaporation is the mechanism, so a cover that keeps dust out and lets vapor go is the requirement, not a seal.

Home chemistry

Small quantities of real reagents in a house. The hazard is unchanged and the controls are gone, which is why the 44 child resistant closures on this shelf matter more than the archetype predicted.

Science fair sample

A sample that travels, sits under lights and is handled by strangers. Leakproof is the requirement and a pressure cycle in a car boot on a warm day is the test.

Label everything, including the boring ones

Water, salt solution, vinegar. A fair display with four unlabelled identical bottles is a project that cannot be checked and a cupboard hazard afterwards.

Keep the quantities small

71 containers at 30 mL or under. For every one of these four leaves, the smallest workable volume is the best answer available, and it is the cheapest.

References

The archetype behind this shelf is ind-lab: 10 to 1,000 mL, narrow mouth, glass and HDPE, cold fill, thin, aqueous, with no dispensing requirement and child resistance recorded as not required. Its stated reason is "reagent or sample. Autoclavability and chemical resistance." Our catalog does not record autoclavability for any product, and of the two materials named only glass is generally autoclavable.

The Davis Pack Supply catalog, measured 18 October 2026. The classroom and home lab shelf is 987 rows: 414 containers and 573 closures. 5 mL to 946 mL with a median of 120; 71 containers at 30 mL or under, 211 at 120 or under, 335 at a pint or under. 154 HDPE, 130 glass, 117 PET, 13 PP. 259 bottles, 150 jars, 3 jugs, 2 tubes. 109 white, 105 clear, 57 natural, 54 amber. Closures: 373 continuous thread, 44 child resistant, 32 dropper assemblies, 27 dome lids, 27 spouted, 19 flip top, 14 phenolic, 10 liners and sealing discs, 9 specialty, 7 buttress, 3 dropper tips and caps, 3 euro droppers.

Written from 29 CFR 1910.1048 and from the catalog as it stood on 18 October 2026. No autoclave cycle is quoted and no container is described as autoclavable, because our data does not record it. School district and state rules on classroom chemicals exist, vary, and are not summarized here.