Kraft Paper Food Packaging Coatings: PE vs PLA vs Water-Based

On this pageWhy Kraft Needs a Barrier The Three Main Coating Routes Side-by-Side Comparison Matching Coating to Food Weight, Thickness and Structure Compliance Checklist Printing on Kraft How to Order Without Surprises Buyer FAQ

Kraft paper looks natural, prints well and is easy to sell as an eco-friendly choice, but an uncoated sheet of paper cannot hold soup, sauce or fried food. What actually decides whether a kraft box or bowl works is the barrier coating on the food-contact side. Choosing the wrong one is the most common reason a kraft pack leaks, goes soft, fails a compliance review or cannot be recycled in the market where it is sold.

Why Kraft Needs a Barrier

Paper is a network of cellulose fibres. Water wicks along them within seconds, and oil follows. A food-grade kraft pack therefore needs one of three things: a plastic film laminated on, a bio-based film, or a thin coating applied as a liquid dispersion. Each trades off barrier strength, heat resistance, end-of-life and cost.

The Three Main Coating Routes

1. PE (polyethylene) lamination

The incumbent. A thin PE layer, usually 10–20 g/m² per side, is extruded onto the paper. It gives excellent liquid and grease barrier, heat-seals reliably (important for cups and folded boxes), and is the cheapest of the three. Downsides: it is a plastic layer, so the pack is not home compostable, and in many markets it is recycled only through specialised paper-mill streams that can separate PE. Always confirm single-side (SPE/PE1S) vs double-side (DPE) coating: cold-drink cups are often single-side, hot-drink cups and soup bowls usually need double-side.

2. PLA (polylactic acid) coating

A bio-based, plant-derived film marketed as compostable. It gives good liquid and grease barrier at room and chilled temperatures and a plastic-free look in the marketing story. The catch is heat: standard PLA softens at roughly 50–60°C, so a PLA-lined bowl is a poor choice for hot soup or microwave reheating unless it is a heat-modified grade. PLA also requires industrial composting; it will not break down in a home bin or a landfill on any useful time scale, and it can contaminate paper recycling if the local system does not accept it.

3. Water-based (aqueous) barrier coatings

The newest route. A water-based dispersion is applied by coating roll, leaving a thin film that provides grease resistance and moderate water resistance, often while the pack can still go into standard paper recycling. They are strongest for dry and oily foods (fries, burgers, pastries, sandwiches) and weaker for long contact with hot liquid. Performance varies widely between suppliers, so ask for test data rather than a brochure claim.

Side-by-Side Comparison

Property	PE coating	PLA coating	Water-based coating
Liquid barrier	Excellent	Good (cold/warm)	Moderate; test for your food
Grease barrier	Excellent	Very good	Good to very good
Hot food (soup, 85°C+)	Yes	Standard grade: no	Short contact only
Microwave reheating	Usually acceptable if the whole pack is rated	Not for standard grade	Depends on formulation
Heat-sealing	Easy	Possible, narrower window	Limited; usually glued or folded
End of life	Specialised paper recycling	Industrial composting where facilities exist	Often standard paper recycling
Relative cost	Lowest	Highest	Middle

Matching Coating to Food

Hot soup, noodles, curry and sauces: double-side PE is the dependable choice. PLA only if the grade is rated for the fill temperature; water-based is not recommended for long liquid contact.
Fried food, burgers, sandwiches, pastry: water-based or light PE. Grease resistance matters more than water resistance here, and the pack should vent steam rather than trap it.
Cold salads and desserts: PLA or PE both work; choose based on the sustainability claim you need to make. See our salad and deli container guide for lid and format options.
Bakery and cake boxes: often uncoated or lightly coated board; see the bakery box guide.

Weight, Thickness and Structure

Coating is only half the story. Paperboard weight is quoted in grams per square metre (gsm). Rigid takeaway boxes commonly use 250–350 gsm board; paper bowls 280–350 gsm plus coating; paper cups use cup-stock around 190–300 gsm. Heavier board resists collapse under hot, wet food, but more fibre means more cost and more freight volume. Ask for the board weight and the coating weight separately on every quotation so that two offers are comparable.

Compliance Checklist

Food-contact migration testing on the finished, coated pack, not just the raw board.
Confirmation that no fluorinated (PFAS) grease-proofing has been added. This is increasingly restricted; see our PFAS-free packaging guide.
If you claim “compostable”, request the certificate for the exact structure sold, and check it is valid for your destination market. A compostable coating on its own is not a compostable pack if the inks, adhesives or lids are not.
Our factory operates under ISO 9001:2015 and BRCGS Packaging, and we can supply SGS third-party test reports for the finished structure on request. For the general rules, read the FDA food-contact guide and the EU compliance guide.

Printing on Kraft

Natural kraft is brown, so flexo and offset inks sit differently than on white board. Expect muted colours unless a white underlay is printed first. Single-colour black or one spot colour on kraft is both economical and distinctive; full-colour photography usually needs white-coated board. Details on artwork and plate costs are in the custom printing guide.

How to Order Without Surprises

State the fill temperature, food type and hold time (for example “soup, 85°C, 30 minutes”).
Ask for the coating type, coating side and board gsm in writing.
Request a pre-production sample and run a real-food leak and softening test for the hold time you need.
Confirm the compliance documents for the structure, then lock the specification in the purchase order.

Send us the food and temperature and we will recommend a structure and quote it. Start from our contact page.

Buyer FAQ

Is PE-coated kraft paper recyclable?

In many regions it can be recycled in mills equipped to separate the thin PE layer, but not in every kerbside system. Check the local rules in your destination market before making a recyclability claim.

Is PLA-coated paper microwave safe?

Standard PLA softens at about 50-60 degrees C, so it is not suitable for microwave reheating of hot or oily food. Only use PLA-lined packs that are explicitly rated for that temperature.

What is the cheapest barrier for kraft soup bowls?

Double-side PE coating is normally the lowest-cost option that reliably holds hot liquid. Alternatives cost more or trade away heat resistance.

Can water-based coatings replace PE?

For dry, oily and fried foods, often yes. For hot liquids with long contact time, PE is still the safer choice unless the supplier shows test data for your exact food and temperature.

How thick should the paperboard be for a takeaway box?

Rigid takeaway boxes usually run 250-350 gsm. Heavier, wetter food needs the upper end. Always ask for board gsm and coating weight separately.