Materials
How to choose a plastic grade for your cosmetic formula
By the Good Partner production and sourcing team. 12 min read.
The mistake buyers make
Material is usually chosen last, after the bottle shape and the decoration are already fixed. By then the useful options have narrowed to whatever fits the tooling that was already bought. Choosing material earlier costs nothing and widens the design space.
Start with the formula, not the bottle
Three properties of your formula drive the decision. Water content and polar content push toward a barrier grade rather than a standard one. Oil and emollient content interacts with some polymer grades over time, so compatibility has to be checked rather than assumed. Active ingredients can be aggressive enough to affect a polymer over shelf life. If your formula is aggressive, the packaging supplier needs to know at the specification stage — not after the first shelf-life problem.
Then narrow by the filling process
Hot fill narrows the usable set considerably. Low fill temperature suits a wider range. In-mould labelling changes the construction completely because the label becomes part of the wall. Each of these removes options you would otherwise carry forward unnecessarily.
Common polymer families
PP is the default for many applications because of cost and chemical resistance. PE is softer and more flexible, which suits squeeze formats. ABS gives good gloss and impact resistance and is frequently used for closures because it takes decoration well. PMMA gives clarity and a premium feel, with the trade-off of lower impact resistance. PET and PCT are common where clarity and chemical resistance both matter. Zinc alloy and aluminium come in for metal components where mechanical function is required.
What to send a supplier
Send the formula profile if you can — including pH, whether it contains solvents or actives, and the fill temperature. Along with the capacity, the decoration and the annual volume, that is enough for a supplier to propose a grade and explain the reasoning. If a supplier quotes a grade without asking about the formula, they are guessing.
Ask why, not just what
The useful question is not which resin but why that one. A supplier who explains the reasoning is choosing; a supplier who names a grade is reading from a list. The difference shows up later when something needs to change.