spherical beads

2 - 4 mm
1 - 3 mm
4 - 8 mm

Non-indicating: spherical beads, white, glassy. Apparent density ap. 750 g/l. The globular shape of the beads allows the air to pass more easily. Beads are therefore most appropriate if silica gel is to be used in thick layers. Internal surface area: 800 m²/g.

Adsorption capacity in percent by weight (25°C):

• RH = 20% / 11 %
• RH = 40% / 20 %
• RH = 80% / 34 %

Granular size: 2 - 5 mm, amporphous granules. This product is replacing the indicating "blue gel" currently presumed to cause cancer. Depending on its moisture content, orange silica gel changes its colour from orange to nearly olourless. Regeneration temperature should not exceed 140°C in order not to damage the indicator.

The colour shift from orange to nearly colourless occurs between 30 - 40% RH. So the colour shift is warning you that the silica gel is approaching its satutation.

Silica gel "neo-blue"

Silica gel "neo-blue" (saturated)

Granular size: 2 - 5 mm, round beads . This product is replacing the indicating "blue gel" currently presumed to cause cancer. Depending on its moisture content, silica gel neoblue changes its colour from blue to red. Silica gel neoblue can be blended with non indicating silica gel, e.g. at a weight ratio of for example 1:10. Regeneration temperature should not exceed 140°C in order not to damage the indicator.

The colour shift from blue to red occurs between 15 - 45% RH. So the colour shift is giving you a good idea about the remaining capacity of the silica gel.

For special applications we still offer cobalt containing blue gel (in stock: 2 - 5 mm or 4 - 8 mm). Prices upon request.

Indicating silica gel, spherical beads. This product is replacing the indicating "blue gel" currently presumed to cause cancer. Depending on its moisture content, orange silica gel changes its colour from orange to colourless. Orange silica gel can be blended with non indicating silica gel, e.g. at a weight ratio of 1:5.
Regeneration temperature should not exceed 140°C in order not to damage the indicator (phenolphtaleine).

The colour change from orange to translucent occurs at 5 - 9% RH, so it's not indicating saturation of the silica gel. There is a lot of adsorption capacity remaining after the colour change has taken place.

6 - 10 mm

Bags of natural clay (bentonite) in non-woven bags, dust-proof according to DIN 55473, can be re-generated many times at 110°C. Bentonite is a non-poisonous natural mineral. DESI PAK bags are approved for packing of food and pharmaceutics (also FDA-approved).

Bentonite can be used for drying up to 50°C. For transports to tropical regions silica gel should be preferred. The vapour uptake of bentonite is similar to silica gel up to an equilibrium moisture content of 40% RH. Above 40% RH, silica gel performs better than bentonite.

The necessary amount of desiccant bags can be calculated if you use a vapour barrier foil with known characteristics and if all edges are well sealed: For HDPE 0,2 mm, you should calculate with a vapour permeation of 0,4 g/m²/day for moderate climate and of 2,0 g/m²/day for tropical climates. For aluminium barrier film you can calculate with 0,1 g/m²/day regardless the climate. If your object is too wet when packed you have to add extra bags.

Re-generation can be done in any conventional household oven at 110°C, for 2 - 4 h. Fan ovens are ideal for this purpose. To check if your bags still release vapour place a hot bag an a cold mirror or cold shiny metal plate. If the bag still releases vapour there will be dew on the mirror immediately. If the bags are cold you also can check with the humidity indicator strip 8% RH delivered along with the bags.

Cheap silica gel bags from China

The non-woven bags have good dust retention, but they are not dustproof according to DIN. The TYVEK-bags are dustproof - excellent quality at a low price, for example for packaging electronic components! Weight indications refer to the gross weight.

All these bags are not approved for food and pharmaceuticals (for these applications please use the Minibags below)
Adsorption capacity: >= 11% at 20% RH, >= 22% at 40% RH, >= 33% at 80% RH.

The paper bags can be re-generated at 130°C, the TYVEK bags at 110°C. The non-woven bags are intended for single use, since the bag material doesn't withstand regeneration temperature .

Molecular sieves 3 Å

The bags can not be re-generated as such, since the bag material doesn't withstand the re-generation temperature of 250 - 300°C. (Theoretically you can open the bags, re-generate the molecular sieves and fill them back into the bags, but normally this doesn't make much sense)