Compostable Bag Materials: A B2B Guide to PBAT, PLA & Starch

Choosing the right compostable bag material is not simply a matter of deciding between PBAT, PLA or starch.

For B2B buyers, the more useful question is:

What material formulation will deliver the required strength, flexibility, thickness, sealing, colour, printing performance and intended end-of-life characteristics for the finished bag?

Flexible compostable bags are commonly manufactured from blends of different materials rather than from a single polymer.

PBAT, starch-based materials and PLA can each play different roles in the formulation, while the final material system should be selected according to the bag application and finished-product requirements.

This guide focuses on material selection from a B2B procurement perspective.

If you are looking for a basic explanation of what compostable bags are made from, start with:

What Are Compostable Bags Made Of?

Last reviewed: October 19, 2026

Compostable Bag Materials at a Glance

For flexible compostable bag manufacturing, commonly used formulation components include PBAT, starch or thermoplastic starch, PLA, processing additives, pigments and printing inks.

Material	Typical Role in Flexible Bag Film	Main Buyer Consideration
PBAT	Main flexible polymer component	Flexibility, toughness and blown-film performance
Corn starch / TPS	Renewable formulation component	Renewable content, film properties, moisture sensitivity and cost
PLA	Additional compostable polymer	Helps adjust formulation and film properties
Additives	Processing and performance adjustment	Must be considered as part of the complete formulation
Masterbatch / pigments	Bag colour	Colour matching, opacity and formulation compatibility
Printing inks	Branding and product information	Print coverage, colour and applicable certification review

The most important point is that the finished formulation matters more than the name of one individual polymer.

Two bags described as “PBAT/PLA compostable bags” can perform very differently if their formulation, thickness, extrusion conditions, sealing structure or printing are different.

ORIZON Typical Compostable Bag Formulation

For many of ORIZON’s flexible compostable bag applications, a typical material formulation is approximately:

Component	Typical Share
PBAT	75%
Corn starch	22%
PLA	2%
Additives	1%
Total	100%

This is a typical ORIZON formulation reference, not a universal formula for all compostable bags in the market.

In this formulation:

• PBAT forms the main flexible polymer component.
• Corn starch provides a significant renewable component within the material system.
• PLA is used at a lower proportion as part of the overall formulation.
• Additives support processing and required finished-film performance.

Depending on the finished product, the formulation may need to be reviewed together with factors such as:

• bag size;
• thickness;
• required strength;
• colour;
• printing;
• sealing structure;
• intended use;
• storage conditions;
• target market;
• applicable certification requirements.

The material formulation should therefore be considered together with the final finished-product specification.

PBAT in Compostable Bag Materials

PBAT stands for polybutylene adipate terephthalate.

It is widely used in flexible compostable film applications because of its flexibility and toughness.

For bag manufacturing, PBAT can contribute properties such as:

• flexibility;
• elongation;
• tear resistance;
• film toughness;
• blown-film processability;
• sealing performance.

These characteristics are particularly important for products such as:

• dog waste bags;
• food waste liners;
• compostable garbage bags;
• produce bags;
• shopping bags;
• other flexible film products.

Is PBAT Plant-Based?

PBAT should not automatically be described as a plant-based polymer.

Conventional commercial PBAT is commonly produced from fossil-derived feedstocks.

This illustrates an important distinction:

Bio-based describes where the material’s carbon comes from. Compostable describes how a material behaves under specified composting conditions.

The two terms are not interchangeable.

A compostable bag can therefore contain both renewable and fossil-derived components.

Corn Starch in Compostable Bag Formulations

Corn starch is an important renewable component in many starch-containing compostable formulations.

However, a compostable bag containing corn starch should not automatically be described as being made entirely from corn starch.

Natural starch alone does not provide all the mechanical and processing characteristics required for most flexible bag films.

In compostable material systems, starch may be modified or incorporated into a blend with other polymers.

Depending on the formulation, starch-based components can influence:

• renewable material content;
• material cost;
• film feel;
• moisture sensitivity;
• mechanical properties;
• processing behaviour.

For ORIZON’s typical formulation, corn starch accounts for approximately 22% of the material composition.

This is substantially different from describing the finished bag simply as a “corn-starch bag.”

The finished film is a multi-component compostable material system.

PLA in Compostable Bag Materials

PLA stands for polylactic acid.

It is a bio-based polyester commonly produced from fermented sugars derived from renewable feedstocks.

PLA is generally more rigid than PBAT.

In flexible bag formulations, it may be used as one component of a broader material system rather than as the main flexible polymer.

For ORIZON’s typical compostable bag formulation, PLA represents approximately 2% of the material composition.

This is important when describing ORIZON products accurately.

Our typical flexible bag formulation is better described as:

a PBAT-based compostable formulation containing corn starch, a small proportion of PLA and processing additives

rather than simply as a high-PLA “PLA/PBAT bag.”

For more information about the different roles of these polymers, see:

Why Compostable Bags Use PLA and PBAT

Why Compostable Bag Materials Are Blended

Flexible bags need several properties at the same time.

A finished bag may need to be:

• flexible enough to unfold easily;
• strong enough for its intended load;
• resistant to tearing or puncture;
• capable of reliable heat sealing;
• suitable for film extrusion;
• printable;
• stable during its intended storage period;
• compatible with the required colour;
• suitable for the intended composting system.

No individual ingredient should be evaluated in isolation.

The purpose of formulation is to create a balanced finished film.

This is why purchasing decisions based only on statements such as:

“This bag contains PLA.”

or:

“This bag contains PBAT.”

provide very limited information about actual bag performance.

Should Buyers Specify a PLA/PBAT Ratio?

For most OEM bag projects, not as the first step.

Unless your company has a specific technical, regulatory or formulation requirement, it is usually more useful to tell the manufacturer what the finished bag needs to do.

For example:

Dog waste bag
230 × 330 mm
18 μm
Soft and flexible
Strong bottom seal
Easy-opening film
Custom Pantone colour
One-colour logo printing
15 bags per roll
Australian market

This gives the manufacturer much more useful information than simply requesting:

“Please make a PLA/PBAT bag.”

The formulation can then be assessed against the required performance.

How to Choose Compostable Bag Materials for Your Application

1. Start With the Bag Application

Different applications require different film properties.

A dog waste bag does not have the same performance requirements as a produce bag or large bin liner.

Before discussing material percentages, define:

• what the bag will contain;
• expected load;
• contact with wet or dry waste;
• puncture risk;
• use duration;
• required flexibility;
• required sealing performance.

This becomes the basis for material selection.

2. Define the Required Thickness

Thickness is one of the most important specifications in flexible bag production.

However:

thicker does not automatically mean better.

Bag performance also depends on:

• formulation;
• film consistency;
• extrusion quality;
• sealing;
• bag dimensions;
• bottom structure;
• perforation;
• manufacturing control.

For example, two 18 μm bags produced from different formulations or under different processing conditions may not provide identical strength.

Buyers should therefore evaluate thickness and formulation together.

3. Define the Required Strength and Flexibility

Ask what type of mechanical performance matters most.

For example:

Dog waste bags

Important characteristics may include:

• puncture resistance;
• flexibility;
• easy opening;
• reliable bottom sealing;
• easy separation at perforations.

Food waste bags

Important characteristics may include:

• wet-waste resistance;
• leak resistance;
• puncture performance;
• bottom sealing;
• fit with the intended bin.

Shopping bags

Important characteristics may include:

• load-bearing performance;
• handle strength;
• tear resistance;
• bottom sealing;
• film thickness.

Different applications therefore require different performance priorities. cost.

Material Selection by Bag Type

Dog Waste Bags

Dog waste bags normally require a soft and flexible film.

Important purchasing considerations include:

• thickness;
• puncture resistance;
• bottom-seal strength;
• easy opening;
• perforation quality;
• roll winding;
• colour;
• printing;
• dispenser compatibility.

A buyer should evaluate physical samples rather than selecting a product only from its polymer description.

Compostable Garbage Bags and Bin Liners

Waste liners may need to handle:

• heavier loads;
• irregular waste;
• wet organic waste;
• longer contact time;
• greater puncture stress.

Specifications should therefore consider:

• dimensions;
• thickness;
• bottom structure;
• load requirement;
• moisture exposure;
• intended collection system.

Small kitchen liners and large commercial bin liners should not automatically use the same film specification.

Compostable Produce Bags

Produce bags usually place greater emphasis on:

• thin flexible film;
• easy opening;
• roll dispensing;
• transparency or translucency;
• perforation quality;
• consistent roll dimensions.

Their performance requirements are therefore different from heavy-duty refuse liners.

Compostable Shopping Bags

Shopping bags generally require greater structural and load-bearing performance.

Buyers should consider:

• bag width and height;
• side gussets;
• thickness;
• handle design;
• bottom sealing;
• expected load;
• colour;
• printing coverage.

Material selection should be based on the completed bag design rather than polymer names alone.

Colour and Masterbatch Considerations

Private-label compostable bags are often produced in custom colours.

Common requirements include:

• natural;
• green;
• black;
• white;
• pastel colours;
• branded Pantone colours.

Colour should be confirmed before mass production because the final appearance can be influenced by:

• film thickness;
• base material colour;
• masterbatch concentration;
• opacity;
• printing colour;
• lighting conditions.

For OEM projects, Pantone references are more useful than general terms such as:

“light green”

or:

“dark purple.”

A physical colour sample or approved digital reference may also be useful before production.

Printing Compatibility

Material selection should also take printing into account.

Custom compostable bags may require:

• one-colour printing;
• multiple-colour printing;
• one-side printing;
• two-side printing;
• repeating logos;
• instructions;
• certification marks where applicable.

Before quotation or production, buyers should specify:

1. number of colours;
2. printing sides;
3. approximate print area;
4. Pantone requirements;
5. artwork format;
6. required bag colour.

For branded bag programs, see: Custom Printed Compostable Bags

Storage and Shelf-Life Considerations

Compostable films should be stored appropriately.

Heat, moisture, direct sunlight and extended storage can influence some materials and finished bags.

However, there is no single shelf-life figure that should automatically be applied to every compostable bag.

Expected shelf life can depend on:

• formulation;
• film thickness;
• packaging;
• storage temperature;
• humidity;
• transportation;
• final bag specification.

B2B buyers should therefore ask for storage recommendations applicable to the specific finished product being purchased.

Avoid assuming that every PBAT-, PLA- or starch-containing product has exactly the same storage behaviour.

Material Formulation vs Finished-Product Certification

This is one of the most important distinctions for compostable bag buyers.

A material formulation containing:

• PBAT;
• PLA;
• corn starch;

does not by itself establish that every finished bag made from that formulation is certified for every market or composting system.

Likewise, having a certified raw material does not automatically establish certification applicability for every possible:

• thickness;
• bag type;
• colour;
• printing configuration;
• finished-product construction.

Certification requirements can relate to the applicable certification scheme and the final product configuration.

The correct principle is:

Certification applicability should be confirmed against the applicable current certificate and final finished-product specification.

For ORIZON certification references and current verification information, see:

ORIZON Evidence & Verification Center

Certifications Should Not Be Selected From Material Names Alone

Terms such as:

• PBAT;
• PLA;
• starch;
• biodegradable polymer;
• compostable resin;

should not be used as substitutes for certification verification.

For example, ASTM D6400 is associated with plastics designed for aerobic composting in municipal or industrial facilities in the United States, while other markets use different standards and certification systems.

A buyer should first determine:

1. target market;
2. intended composting system;
3. required product type;
4. finished-product specification;
5. applicable certification or regulatory requirement.

Only after these points are known should certification applicability be confirmed.

Target Market Matters

Material selection is only one part of a B2B compostable bag project.

The intended market should also be identified at the beginning.

Examples include:

United States

Buyers may need to consider applicable ASTM requirements, BPI certification requirements, labelling rules and local composting acceptance.

European Market

Applicable EN standards, certification schemes, labelling and local waste-management requirements may need to be considered.

Australia

Depending on the intended application and composting system, Australian buyers may need to consider requirements associated with industrial or home compostability, together with local council, waste-contractor or composting-facility acceptance.

A bag should therefore not be developed first and have its certification strategy considered only afterwards.

Why Finished Bag Performance Matters More Than Polymer Names

When comparing two suppliers, a buyer may see:

Supplier A: PBAT + PLA + starch
Supplier B: PBAT + PLA + starch

This does not mean the products are identical.

Differences may exist in:

• material proportions;
• additives;
• thickness;
• thickness tolerance;
• extrusion quality;
• sealing;
• perforation;
• printing;
• masterbatch;
• production consistency.

The better comparison is therefore:

How does the finished bag perform against the agreed specification?

rather than:

Does the ingredient list contain the same polymer names?

Sample Testing Before Mass Production

For a new OEM or private-label project, physical sample evaluation is strongly recommended.

Depending on the application, buyers may evaluate:

• dimensions;
• thickness;
• film feel;
• opening performance;
• puncture resistance;
• tear behaviour;
• bottom sealing;
• perforation;
• colour;
• printing;
• roll winding;
• dispenser compatibility;
• bin fit.

Sample evaluation is particularly important when changing:

• thickness;
• bag dimensions;
• formulation;
• colour;
• packaging configuration.

The approved sample can then provide a practical reference for mass production.

What B2B Buyers Should Include in an RFQ

A request such as:

“Please quote compostable bags.”

does not provide enough information for an accurate OEM quotation.

A better RFQ should include:

Specification	Example
Bag type	Dog waste bag
Width × length	230 × 330 mm
Thickness	18 μm
Bottom structure	Star seal
Colour	Pantone reference
Printing	1 colour / 1 side
Bags per roll	15
Rolls per box	20
Order quantity	5,000 rolls
Target market	Australia
Packaging	Private-label retail box
Intended use	Dog waste collection
Certification requirement	Confirm according to target market and final specification

With this information, the manufacturer can evaluate:

• material formulation;
• production feasibility;
• printing;
• packaging;
• certification applicability;
• MOQ;
• pricing.

Questions to Ask a Compostable Bag Manufacturer

1. What finished-product specification is being quoted?

Confirm:

• size;
• thickness;
• bag structure;
• colour;
• printing;
• roll configuration;
• packaging.

Do not compare quotations based only on price per bag or price per roll.

2. What material formulation is proposed?

The supplier should be able to explain the basic formulation and why it is suitable for the application.

For ORIZON’s typical flexible compostable bag formulation, the reference composition is approximately:

75% PBAT + 22% corn starch + 2% PLA + 1% additives.

3. Can samples be tested before bulk production?

For new projects, sample testing helps confirm whether the proposed thickness, feel and bag structure are appropriate.

4. What production tolerances apply?

Confirm relevant tolerances for:

• dimensions;
• weight;
• quantity;
• thickness where applicable.

This helps prevent unrealistic comparisons between quotations.

5. Can custom colour and printing be produced consistently?

Private-label buyers should confirm:

• Pantone colour;
• printing colours;
• print position;
• print sides;
• packaging artwork.

Production consistency becomes particularly important for repeat orders.

6. What documentation applies to the final product?

Ask specifically about the finished-product configuration being purchased.

Do not assume that a certificate held by a material supplier automatically covers every finished bag.

7. What are the recommended storage conditions?

The answer should relate to the actual finished product rather than a generic statement about all compostable polymers.

Material Cost Should Not Be the Only Purchasing Factor

Raw-material cost is important, but it is only one part of the final bag cost.

Other commercial factors include:

• thickness;
• bag dimensions;
• bag weight;
• printing;
• colour masterbatch;
• conversion efficiency;
• packaging;
• carton requirements;
• production quantity;
• tooling or printing plates;
• shipping.

For example, reducing the raw-material cost per kilogram does not necessarily create the lowest-cost finished bag if the alternative formulation creates processing problems or requires greater film thickness.

B2B buyers should therefore evaluate finished-product cost and performance together.

Why Consistent Production Matters

A successful material formulation still requires consistent manufacturing.

Flexible compostable bag production involves several controlled stages, including:

1. material preparation;
2. film extrusion;
3. film thickness control;
4. printing where required;
5. sealing and cutting;
6. perforation;
7. rolling or folding;
8. inspection;
9. packing.

Material selection and manufacturing control therefore work together.

Poor process control cannot always be solved simply by choosing a different polymer.

FAQ About Compostable Bag Materials

What is the best material for compostable bags?

There is no single best material for every compostable bag.

The appropriate formulation depends on the required flexibility, strength, thickness, bag structure, printing, colour, storage conditions, intended use, target market and applicable certification requirements.

What materials does ORIZON typically use for compostable bags?

For many flexible compostable bag applications, ORIZON’s typical formulation is approximately:

• 75% PBAT
• 22% corn starch
• 2% PLA
• 1% additives

The exact suitability of a formulation should still be reviewed against the final product specification.

Is PBAT plant-based?

Conventional commercial PBAT is commonly fossil-derived.

The term “compostable” describes end-of-life behaviour under specified composting conditions and should not be treated as equivalent to “plant-based.”

Is PLA plant-based?

PLA is generally produced from renewable sugar-based feedstocks and is commonly classified as a bio-based polymer.

However, using PLA does not by itself establish that a finished bag is certified compostable.

Are compostable bags made from corn starch?

Some compostable bag formulations contain corn starch, but the finished flexible film is generally a blend of several components.

For ORIZON’s typical formulation, corn starch accounts for approximately 22%, together with PBAT, PLA and additives.

Is more PLA better for a compostable bag?

Not necessarily.

A flexible bag requires a balance of different properties.

Increasing one polymer changes the formulation and may affect stiffness, flexibility, processing and other characteristics.

The appropriate formulation should be based on the required finished bag.

Should I specify the PLA/PBAT ratio when requesting a quotation?

Usually not unless your project has a specific technical requirement.

For most OEM projects, it is more useful to provide the bag application, size, thickness, strength requirement, colour, printing, packaging and target market.

Does a thicker compostable bag always mean a stronger bag?

No.

Thickness is important, but strength also depends on formulation, film extrusion, sealing structure, bag dimensions and production consistency.

Can custom colours be added to compostable bags?

Yes, depending on the required formulation and finished-product specification.

For private-label projects, buyers should normally provide a Pantone colour reference.

The colour system should also be considered when reviewing the final configuration and applicable certification requirements.

Can compostable bags be custom printed?

Yes.

Custom logo printing, product information and branding can be produced according to the required specification.

Print colours, coverage, sides and artwork should be confirmed before mass production.

See:

Custom Printed Compostable Bags

Does using PBAT, PLA and starch automatically make a bag certified compostable?

No.

Polymer names or formulation ingredients alone should not be used to establish finished-product certification.

Certification applicability should be confirmed against the applicable current certificate and final finished-product specification.

Conclusion

Choosing compostable bag materials for a B2B project should not start with:

“Should I buy PLA, PBAT or starch?”

A better starting point is:

“What does the finished bag need to do?”

Define the required:

• application;
• size;
• thickness;
• strength;
• flexibility;
• sealing;
• colour;
• printing;
• packaging;
• target market;
• certification requirements.

The manufacturer can then evaluate the appropriate material formulation and production configuration.

For many ORIZON flexible compostable bag applications, a typical formulation is approximately:

75% PBAT + 22% corn starch + 2% PLA + 1% additives.

This formulation is used as a production reference for balancing the requirements of flexible bag manufacturing, but it should not be treated as a universal formula for every compostable bag or every finished-product configuration.

Most importantly:

material composition, finished-product performance and certification applicability are three related—but different—questions.

Buyers should evaluate all three before approving a commercial compostable bag project.

For a basic explanation of compostable bag composition, see:

What Are Compostable Bags Made Of?

For more information on the roles of PLA and PBAT, see:

Why Compostable Bags Use PLA and PBAT

For ORIZON certification references and current scope information, see:

ORIZON Evidence & Verification Center

For OEM and private-label manufacturing enquiries, see:

Compostable Bag Manufacturer