Bio-Based vs Biodegradable Masterbatch — Which Certificate Actually Applies
Direct answer
"Bio-based" and "biodegradable" answer two different questions and are certified by two different families of documents. Bio-based describes where the carbon came from and is evidenced by a bio-based carbon content result. Biodegradable or compostable describes what happens at end of life and is evidenced by an industrial or home compostability certification for the finished article, not for the masterbatch alone. A masterbatch can be fully bio-based and not compostable, and it can be compostable while made from fossil carbon.
The certificate is on the article, not on the pellet
This is the point that most often breaks a project late. A compostability scheme certifies a finished product at a stated thickness and formulation. A masterbatch supplier can supply a grade that is suitable for use in a certified article and can supply the supporting evidence, but the certificate that a retailer or regulator asks for is issued against your article, after your own testing.
Plan for that: the masterbatch decision has to be made early enough that the article certification can be run on the actual formulation you intend to sell.
Pigment and additive constraints tighten
Compostable formulations restrict what can be present — heavy metal limits, ecotoxicity on the disintegration residue, and total non-biodegradable content including pigments and fillers. A shade that is trivial in a conventional colour masterbatch may not be achievable inside those limits, or may need a different pigment with a different opacity and cost. Bring the colour target to the conversation at the same time as the compostability requirement, never after.
Processing is less forgiving
PLA and PBAT carriers have narrower thermal windows than polyolefins and are moisture sensitive. Expect to revisit drying, melt temperature profile and residence time. A concentrate that disperses fine in LDPE can char in a PLA line at the same settings.
What "carbon neutral" claims are worth
Bio-based carbon content is a measurement. Carbon neutrality is an accounting claim built on top of assumptions about land use, transport and end of life. Only the first belongs on a technical specification. Keep the two separate in your marketing copy as well — advertising regulators in several markets now treat unsupported degradability and neutrality claims as actionable.
What to send with the enquiry
Target polymer system (PLA, PBAT, blend or bio-polyolefin), the scheme you must satisfy and in which market, article thickness, colour or functional target, whether the end use is food contact, annual volume, and the date your article certification testing is planned. Those items decide whether a standard grade fits or a project formulation is required.