Does Your Paper Desiccant Contain Silica Gel? Four Fields on the Datasheet That Tell You

The term is genuinely confusing, and the confusion is not your fault. Two very different products are sold under the same words, and buyers often discover the difference only when a sustainability team asks where the insert goes at end of life.

The two things called paper desiccant

Field 1: basis weight, in GSM

Published US desiccant papers sit a long way apart. A heavy grade is quoted at 460 lbs per 3,000 ft², which is 749 GSM. A light grade is quoted at 105 lbs per 3,000 ft², which is 171 GSM. That is more than four times the mass per unit area, and it is mostly mineral, not fiber.

Why it matters to you: packaging EPR fees are assessed on component weight. A heavy mineral-loaded sheet is a heavier declared component than a thin fiber card doing the same job. The arithmetic is in what a 3 gram desiccant costs under US packaging EPR.

Field 2: caliper, in mils or mm

The heavy grade above is published at 57 mils, which is 1.45 mm. The light grade is 14 mils, or 0.36 mm. For comparison, a plant-fiber card is supplied at 0.5 mm or 1.0 mm.

Caliper is the field that decides whether the insert physically fits your pack. A 1.45 mm board will not go into a blister cavity or a cassette well that a 0.5 mm card clears easily. Formats are compared in desiccant sheets, rolls or die-cut cards.

Watch for datasheets that advertise a choice of thicknesses and then publish neither value. That is common, and it is a reason to ask before you design around it.

Field 3: percent desiccant by weight

This is the single most revealing field. If a datasheet tells you the product is 65% silica gel, you now know three things: it contains silica gel, the remaining 35% is a carrier that does little adsorbing, and the recyclability conversation will be about mineral content.

Read this field sceptically, because published numbers are not always internally consistent. One widely cited US desiccant paper datasheet states 65% silica gel in its specification table and 67% in the body text on the same page, and gives the thickness as 57 mils in the table and a nominal 54 mils in the text. Those are small discrepancies, but they are in the document your QA team will file as evidence, so ask for a signed version.

Field 4: activation condition

If the datasheet says the product must be baked, and quotes something like one minute at 500 °F or five minutes at 300 °F, it is a silica-impregnated paper. Those temperatures drive water off silica gel. They also mean the material arrives inactive unless you pay for it activated and sealed, and that any exposure on your line starts consuming capacity before the pack is closed.

The field that is usually missing: capacity with test conditions

Capacity is quoted inconsistently or not at all. One grade publishes 0.07 g of water per in², described as calculated, with no test conditions stated. Another well-known cellulose-and-silica product publishes no capacity figure anywhere, no temperature range, no humidity range and no test standard, describing its performance only as exceptional.

A capacity number without a temperature and a relative humidity is not comparable to anything. Insist on both. The method for putting two quotes on the same basis is in how to compare desiccant spec sheets.

What a plant-fiber datasheet looks like instead

For contrast, here is the ATMOSIScience® fiber desiccant stated with its test conditions, all at 25 °C:

Fiber desiccant technical criteria at 25 °C — ATMOSIScience

On end of life, the figure to ask any supplier for is a recyclability assessment with a report number. SGS report CQMR260700043401, dated 17 July 2026, classifies the plant fiber desiccant as paper and returns a fibre yield of 69.78% with a recyclability score of 100 out of 100. That result covers the fibre layer and not an assembled finished product, which is a limit worth stating plainly rather than hiding. Full specifications sit in the Fiber Card spec guide, and the category overview is in what a paper desiccant is.

Frequently asked questions

Is paper desiccant the same as fiber desiccant?

Usually not. Paper desiccant in US trade usage normally means cellulose paper impregnated with silica gel beads. A fiber desiccant uses the plant fiber itself as the adsorbent and contains no silica gel.

How can I tell without calling the supplier?

Look for a stated percent silica gel and a bake-out activation temperature. Either one present means silica is in the product.

Can silica-impregnated desiccant paper go in paper recycling?

Treat that as unproven unless the supplier gives you a recyclability assessment with a report number and a stated scope. A sheet that is 65% mineral by weight behaves very differently in a pulping test from one that is mostly fiber.

Does a lower silica content mean weaker performance?

Not necessarily, because what matters is grams of water held per gram of insert at your storage humidity, not the percentage of any one ingredient. Compare on capacity at a stated temperature and relative humidity.

Which format should I ask for?

Match caliper to the space you have, then size by capacity. If the pack is tight, start from the 0.5 mm card. If the pack is a carton or a shipper, a pouch is usually simpler to insert.