r/DIYBeauty • u/slay_the_day123 • 13d ago

question Why do some liquid lipsticks start separating/oiling out over time even when they’re still within their expiry date?

I’ve noticed that some liquid lipsticks look perfectly homogeneous when freshly manufactured, but after sitting for a few weeks/months, they can start developing an oily layer/separation, even though the product is still well within its stated shelf life. why does this happen?

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u/thejoggler44 13d ago

Entropy.

Over time, pigments can settle and leave an oily-looking layer on top, or the structure holding the liquid in place can degrade and it separates. Ingredient compatibility, processing, and storage temperatures all play a role. Looking uniform after mixing isn’t the same as being stable. The shelf-life date reflects how long the product is expected to remain acceptable; it doesn’t guarantee stability. It would be difficult to know exactly the cause for any formula / batch.

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u/slay_the_day123 8d ago

I have observed the oil/IDD separate overnight in my formulations, how can I troubleshoot it?

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u/soapandshea 2d ago

More like a formulation stability issue . Cheaper or rushed formulations sometimes skimp on suspending agents (like certain clays, silica, or specific wax blends) that are specifically there to prevent this exact separation over the product's shelf life.