Reading a Seaweed Specification Sheet: Grades, Impurities and Limits

A specification sheet for dried seaweed looks short: a species, a handful of parameters, a few maximum or minimum values. Each line, though, carries a commercial consequence. It decides how a lot is tested, what counts as a defect and who pays when a shipment falls short. This guide walks through the lines you will typically see and what to watch for in each.

The parameters, line by line

• Species and origin: the seaweed named botanically — for example Kappaphycus alvarezii (cottonii) or Eucheuma denticulatum (spinosum) — and the country or region. Vague descriptions such as “red seaweed” leave room for mixing.
• Moisture: a maximum water content, with the test method stated. It is the single parameter with the largest effect on weight and price.
• Impurities or foreign matter: a maximum for anything that is not the specified seaweed — sand, stones, rope, plastic, other species. Check whether it is measured by visual sorting or by weight after cleaning.
• Salt or ash: surface salt left from seawater adds weight but no value. Some buyers specify salt, others total ash, which also includes minerals in the seaweed itself.
• Clean anhydrous weed (CAW): the share of the lot that is clean, dry seaweed once water, salt and impurities are removed. Processors often value this above any other figure.
• Gel strength or yield: for carrageenan seaweeds, a laboratory measure of how the extracted carrageenan performs. It depends on species, growing conditions, harvest age and handling.
• Appearance and condition: colour, absence of mould, and whether the seaweed is whole or broken.

For more detail on the two most commercially important figures, see our explainers on moisture content and clean anhydrous weed.

How to read a limit

A number alone means little without three pieces of context. First, the method: moisture measured by oven drying and by a handheld meter can give different answers. Second, the sample: a result is only as good as the sample it came from, which is why the sheet should refer to an agreed sampling procedure. Third, the consequence: does exceeding the limit trigger a price adjustment, a right to reject, or nothing at all?

Watch also for the difference between a typical value and a guaranteed one. A supplier’s product description may quote typical figures; a contract specification should state limits the lot must meet.

Negotiating a specification that works

A good specification is one both sides can actually meet and verify. When agreeing one, work through these steps:

1. Start from end use. A semi-refined processor and a refined carrageenan plant may prioritise different parameters; our comparison of semi-refined and refined carrageenan explains why.
2. Fix the test methods. Name the method for every parameter and who performs it.
3. Agree sampling. Refer to a procedure for drawing, splitting and sealing samples — see how to get a representative sample.
4. Set adjustments, not just limits. A clear price adjustment for moisture above the limit usually prevents more disputes than a bare rejection clause.
5. Decide how disputes are settled. Name a referee laboratory or independent surveyor in advance.

Grades and what they really mean

Suppliers and traders sometimes describe lots by grade names. These are not standardised across the industry and can mean different things to different people. Treat a grade name as shorthand for a set of agreed parameters, and make sure those parameters are written down. If a supplier cannot tell you what their grade means in numbers and methods, the grade is not yet a specification.

Frequently asked questions

Working with Kospermindo

Kospermindo aggregates dried seaweed from organised farmer groups in South and Central Sulawesi and works in long-term partnerships with processors and exporters. See our products and trade page to discuss specifications for your requirements.