How much water can a calcium chloride desiccant absorb?

High-purity calcium chloride absorbs 300 to 600 percent of its own weight in water, because it absorbs chemically by deliquescence rather than adsorbing on a surface. BENZPACK BE DRY reaches up to 500% and BE DRY ULTRA up to 600%, far above the roughly 25 to 40% of silica gel.

Why is calcium chloride better than silica gel for shipping containers?

Calcium chloride has many times the capacity and, crucially, its absorption rate accelerates as humidity rises, so it keeps working through the high-humidity peaks of a long voyage. Silica gel saturates early and stops absorbing while the dew-point cycle continues, so it cannot keep a long container voyage dry.

Does calcium chloride desiccant leak?

Raw calcium chloride forms a liquid brine, but BENZPACK BE DRY and BE DRY ULTRA bind the absorbed water into a stable gel inside a multi-layer leak-proof housing, verified under maritime vibration, impact and inversion, so there is no brine drip onto cargo or the container floor even when fully saturated.

Is calcium chloride desiccant safe for food cargo?

Yes. BENZ calcium chloride desiccants are compliant with EU food-contact regulation EC 1935/2004 for containers carrying non-direct-contact food cargo and are REACH-registered, with the leak-proof gel ensuring no liquid reaches the cargo.

Desiccant Technology

Calcium Chloride Desiccant

Calcium chloride is the highest-capacity desiccant in commercial use, absorbing several times its own weight in water where adsorbents like silica gel manage a fraction of theirs. That single property is why it, and only it, reliably eliminates container rain on long ocean voyages. Here is the chemistry, the capacity, the leak-proof gel that makes it shippable, and the BENZ products built on it.

Reviewed by the BENZ Packaging technical team · Updated June 2026

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The Chemistry

Deliquescence: Absorption, Not Adsorption

Most desiccants adsorb, water clings to the surface of a porous solid, and capacity is capped by surface area. Calcium chloride (CaCl₂) does something different: it absorbs. It is deliquescent, meaning it chemically attracts water vapour, reacts with it and dissolves into a calcium chloride brine. Because the reaction continues until all the available calcium chloride has been consumed, the capacity is governed by how much active salt is present, not by a fixed surface area. This is why high-purity calcium chloride absorbs 300 to 600% of its own weight in water, against roughly 25 to 40% for silica gel.

The second crucial behaviour is the kinetics. The absorption rate is driven by the vapour-pressure difference between the brine and the surrounding air, and that difference grows as humidity rises. So calcium chloride absorbs fastest precisely at the 80 to 100% RH peaks where container rain forms, the opposite of silica gel, which slows as it approaches saturation. A calcium chloride desiccant is most aggressive exactly when the moisture threat is greatest.

Why Capacity and Kinetics Decide Container Protection

The properties that make calcium chloride the container desiccant.

300–600% Capacity

Several times the moisture per kilogram of any adsorbent, so a long voyage's litres of condensate can be absorbed by a handful of units.

Accelerates With Humidity

Absorbs fastest at the high-RH peaks where container rain forms, sustaining protection deep into the voyage.

Wide Temperature Range

Effective from around –25°C to +70°C, covering the climate swings of trans-ocean routes.

Leak-Proof Gel

BENZ binds the absorbed brine into a stable gel that cannot drip, so there is no liquid on the cargo or container floor even when saturated.

Food-Contact & REACH

EC 1935/2004 compliant for food cargo and REACH-registered for the EU market.

DIN 55473 Sized

Quantity calculated by Desiccant Unit so the dew point is suppressed for the whole transit.

The Engineering Problem It Solves

The Leak-Proof Challenge, and How BENZ Solves It

The one drawback of raw calcium chloride is exactly what makes it powerful: it turns into liquid brine. An untreated calcium chloride desiccant can drip saturated brine onto cargo and corrode the container floor, which is why cheaper products carry a brine-drip risk. BENZ engineers this out: in BENZPACK® BE DRY™ and BE DRY™ ULTRA the absorbed water is locked into a stable gel within a multi-layer, gel-retaining housing, verified leak-proof under maritime transit vibration, impact and inversion. You get the capacity of calcium chloride with none of the mess, which is why it is shippable in full-container loads.

BENZ Calcium Chloride Desiccants

Two grades on one ladder.

BENZPACK® BE DRY™

≥90% CaCl₂, up to 500% absorption, 60–90 day life, DIN 55473. The standard for 20–30 day routes. Details ›

BENZPACK® BE DRY™ ULTRA

≥94% CaCl₂, up to 600% absorption, 90–120 day life, for the longest, most humid voyages. Details ›

Need clay instead?

For sealed barrier bags with electronics, metals or pharma, nitrite-free C DRY clay is the safe choice. C DRY ›

Specifying a Calcium Chloride Desiccant? Let Us Calculate It

Send your container, cargo and route and our team will calculate the exact units and supply leak-proof, DIN 55473-certified BENZPACK desiccants, free, worldwide.

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