Greaseproof paper, with and without fluorine
Grease resistance can be built two ways: by treating the surface so oil will not wet it, or by closing the sheet so tightly that oil cannot travel through it. The second is harder to make and is where the market has moved.
Two different mechanisms
Fluorochemical treatment works on surface energy. The oil does not wet the sheet, so it does not penetrate. It is effective at low coat weights and works on a relatively open sheet.
Fluorine-free grease resistance is structural. The sheet is refined and calendered until the fibre network itself is dense enough that oil cannot pass — the same principle as glassine — or a barrier is applied that is not fluorochemical.
The first is a treatment on the paper. The second is a property of the paper.
Why the distinction is on every enquiry now
Several markets have restricted or are restricting fluorochemicals in food contact materials, on different timetables and with different scope. Buyers who export finished packs into more than one market increasingly specify fluorine-free by default rather than track each rule.
The rules differ by market and they change. We supply both and we will tell you which is which; establishing what your destination market requires is the buyer's call, and it is worth settling before the order rather than after.
What each is good at
Fluorine-free grades tend to be denser and stiffer at the same grammage, and can be less forgiving to convert. They hold grease well and are the safer specification where the destination market is uncertain.
Fluorochemical grades run softer and are cheaper to achieve a given resistance level. They remain in use where the market permits them and where the pack is not food contact at all — industrial interleaving, for instance.
What to send
The contents and how hot and greasy they are, the contact time, the destination markets, and whether the sheet is printed or laminated afterwards. Grease resistance is measured against a test and a duration — say which one your customer is asking for.
Questions
What is fluorine-free greaseproof paper?
Paper whose grease resistance comes from the density of the sheet itself — heavily refined and calendered — or from a non-fluorochemical barrier, rather than from a fluorochemical surface treatment.
Is fluorine-free greaseproof paper as effective?
For most food packaging uses, yes, though it is achieved differently and the sheet behaves differently on the converting line. Specify the test and the duration your customer requires and it can be matched against a grade.
Which one should I specify?
If you ship into more than one market, fluorine-free is the specification that travels. If the destination is settled and permits fluorochemicals, both are available. Confirm your market's requirement before the order.