Why don't oils use plastic droppers?

Question

As shown in the picture, most cosmetic oils and serums make use of glass droppers. However in the chemistry lab, scientists often also use reusable plastic droppers as well. My question was that, apart from the benefits of glass being eco-friendly and more durable, why don't most oils come with reusable plastic droppers. Especially oils in smaller quantities. Won't it be cheaper for the companies as well? Is there any "chemical explanation" as to why oils are not compatible with plastic droppers (assuming storing the plastic dropper in the oil, as well)? Or is it that glass droppers are just more convenient?

Answer 1

It is (not always but often) about mutual chemical/physical compatibility.

Glass vessels/accessories are generally used

• as general long term storage material
• in analysis of trace amounts of organic compounds
• for long term contact with organic solvents and liquids
• to avoid extraction of plastic components to the organic liquids ( or the other way, diffusion the minor components from the liquid to plastics)
• to avoid affecting plastic properties by organic liquids (dissolving, swelling, softening)
• For historical/traditional reasons
• For better durability

Plastic vessels/accessories are used

• as long term storage for specific anorganic liquids as solutions of alkali hydroxides or hydrofluoric acid.
• to avoid affecting of glass by above solutions
• in analysis of trace amounts of heavy metals, to avoid interaction solution - glass surface.
• in scenarios not critical due listed conditions as cheaper alternative.

In particular case of the question, plastic accessories may swell/soften in long-term contact with oils and oils may extract from plastic unwanted components.

Answer 2

Some plastics are attacked or degraded by certain oils, which might ruin the dropper or make the oil unsafe by leaching chemicals into it. Glass is used because it's inert - the only chemicals that can degrade it are far too dangerous to keep around people anyway, and it won't leach chemicals into the oil either.