How to Write a Desiccant Specification for a Purchase Contract

A desiccant specification has to pin down four things a buyer can actually inspect: what the desiccant is, how much is in each pack, what the sachet is made of, and what performance and documents come with it. If your contract names only "silica gel 5 g", you have left the grade, the sachet material, the performance target and the paperwork undefined — and every one of those can legitimately differ between suppliers.

The Core Fields

1. Product type and grade. Name the material and, where it matters, the grade — for example narrow pore (Type A) silica gel, or a montmorillonite clay desiccant, rather than "desiccant".
2. Net weight and tolerance. State the fill weight per sachet (or per bag) and an acceptable tolerance. Our standard fill range runs from 0.5 g up to 1000 g, so write the exact weight you need.
3. Sachet material and format. Specify the sachet material — composite paper, tea paper, non-woven fabric, OPP film, DuPont paper or Aihua paper — and whether the product is a sachet, a roll or bulk.
4. Performance target. Give the adsorption capacity at stated humidity levels. Standard reporting is at RH 20%, RH 50% and RH 90%, so your contract can hold a supplier to a measurable figure rather than a claim.
5. Physical and chemical data. As applicable: pore size, pore volume and specific surface area; bulk density; loss on heating; particle size and qualified size ratio; SiO₂ content. These are the figures printed on the product data sheet.
6. Safety and hygiene limits. For food or pharmaceutical packaging, add the microbial limits a supplier can test to, and name the standard you require.

Reference the Standard You Are Buying To

Where a standard exists for your use, write it into the specification rather than relying on a generic label. Two examples from our own product range: our medicinal and food desiccant conforms to YBB00122005, "Medicinal silica gel desiccant in solid paper bags" — a specification that also sets microbial limits, including a limit on bacteria and mould per bag and "not detected" for E. coli. Our calcium chloride container desiccant references T/CPF 0104–2025 for composite chloride desiccant for packaging. Naming the standard is what turns a vague grade into something a lab can verify.

Specify the Documents, Not Just the Goods

A purchase contract for desiccant is also, in practice, a document order. Decide up front which of these you need, and put each one in the specification so it is a condition of supply rather than a later favour:

• Technical data sheet for the exact grade and fill weight.
• Safety data sheet (SDS), which we can supply for products on request.
• Food contact or compliance statement where the sachet goes inside food or pharmaceutical packaging — see our reference on desiccant for food and pharmaceutical packaging.
• Heavy-metal documentation where the packaging enters the EU; the rules are set out in our guide to the PPWR heavy-metal limit.
• Batch certificate of analysis where your quality system needs it.

Packaging, Marking and Quantity

• Carton, bag or drum, and the units per outer. Specify whether bulk comes in woven bags, composite bags or container bags.
• Marking and labelling, including any printed artwork, warning text, or customer-specific printing on the sachet.
• Quantity and MOQ. State your order quantity; we accept small-batch customisation from 1 tonne and welcome OEM and ODM projects.
• Price basis. Our products are quoted on request, so state the quantity and delivery terms you are buying against and ask for a quotation — prices are set per enquiry, not published.

Storage and Handling Clause

End the specification with the storage and handling conditions you expect the goods to be supplied and kept under — typically store in a dry, ventilated place and keep sealed against moisture — plus any product-specific warnings. An oxygen absorber, for instance, must not be microwaved or eaten and should be used within 1 hour of opening. Writing these down protects the goods after delivery as well as before it.

A One-Page Specification Template

If you want to keep it short, these ten lines cover the substance of most orders: (1) material and grade; (2) fill weight and tolerance; (3) sachet material and format; (4) adsorption capacity at RH 20 / 50 / 90%; (5) loss on heating; (6) particle size and qualified size ratio; (7) standard reference; (8) microbial or safety limits if applicable; (9) required documents; (10) packaging, marking, quantity and delivery terms.

Send us that specification and we will confirm what we can meet, flag anything that needs discussion, and quote it.