ART SORB

Important information:
For most applications we recommend our product "PROSORB" which offers superior properties between 40 - 60 % RH and is much cheaper. But we continue to sell ART SORB conditioned to 65 - 75% RH (adsorption between 75 - 80% RH is very small and therefore it is almost impossible to condition to RH 80%)

ART SORB is a type of silica gel which is well suited to the task of controlling humidity in display cases. It is a moisture-sensitive silica material which adsorbs and desorbs moisture in order to offset changes in relative humidity. Its main use is to create a suitable microclimate inside showcases placed in rooms which are either too dry or too wet or subject to a fluctuating climate.

ART SORB represents a solution in passive buffering systems for conservation of certain works which have to be maintained between 60 - 75 % RH.

ART SORB is composed silica gel and lithium chloride. It is available in beads and cassettes for simple incorporation into any well-sealed display case or storage cabinet. Upon request, ART SORB can be filled into custom made sachets of TYVEK.

BEAD TYPE:

Granular size: 1,5 – 4 mm/bead; colour: white/translucent; bulk density: 500 g/litre.

For most efficient use of ART SORB spread beads in thin layers over a large surface area. Beads also can be placed in drawers, flat trays or any container made of suitable material. Between 0,7 and several kilograms of beads per cubic metre air volume are required depending on circumstances and the desired buffering effect (see our leaflet "How to use ART SORB..."). The beads are shipped to you pre-conditioned at 65 - 75% RH. A calibrated hygrometer is required to re-condition bead type ART SORB to its original RH-value.

CASSETTE TYPE:

ART SORB–cassettes are much easier to handle than ART SORB beads. They don’t need trays or containers and are exchanged in a second. Re-conditioning to their original RH-value can be done easily by weight, at least during the first year of use. Due to slow degradation of the ART SORB the conditioning value slowly shifts upwards at a given weight, typically by 1% - 1,5% RH per year. After some years of use, you imperatively have to measure RH of the cassette after re-conditioning (see below).

The cassettes are made of PP and polyester non-woven. Full-size and half-size cassettes are available. We use the same cassettes as for PRO SORB.

 

FULL SIZE CASSETTES: Size: 335 x 110 x height 44 mm. They are filled with 750 g ART SORB beads (dry weight). One ore more cassettes per cubic metre of air volume are reqired depending on circumstances of application (see "How to use ART SORB").

 

HALF SIZE CASSETTES: Size: 335 x 110 x height 24 mm. They are filled with 400 g ART SORB beads (dry weight). One half-size cassette will be sufficient for 0,7 m³ maximum depending on circumstances of application (see "How to use ART SORB").

 SHEET TYPE:





Size: 500 x 500 x 1,8 mm. Dry weight about 160 g/sheet (100 grams of ART SORB per sheet). They are composed of ART SORB particles bound in a PE/PP non-woven.

ART SORB sheets are ideal for small spaces such as framing systems and for vertical applications like on back side of display cases. Due to their large active surface sheets are often used to buffer short term changes in relative humidity. They can be cut to appropriate size with scissors or a cutter knife. ART SORB sheets are available pre-conditioned at 50% RH only, but they adapt rapidly to other climatic situations when exposed in a room with a given relative humidity.

Please be aware that these sheets give off fine dusts of ART SORB during handling. This dust contains corrosive LiCl and should not get into contact with art works, specially metals. Be sure not to transfer this dust on your artwork through your hands or gloves. In case these dusts are a problem, the ART SORB should be sealed into permeable but dustproof materials like TYVEK.

TECHNICAL DATA:

Chemical Composition:

ART SORB consists of 90% silica gel (SiO2) and lithium chloride (LiCl). ART SORB does not off-gas and will even take in a small amount of organic volatiles. Acid contaminants however degrade ART SORB with time as they do with any silica gel.

High moisture capacity (EMC = equilibrium moisture capacity):

Equilibrium Moisture Content is the actual amount of water adsorbed by the silica gel when its vapour pressure is at equilibrium with a given relative humidity (RH). A high EMC indicates a large capability to buffer changes in RH. ART SORB has a unique high adsorption / desorption capability throughout the entire range of RHs (see Table 1).

High M-Value:

The M-value represents the amount of water in grams that is gained or lost by one kilogram of gel when the RH changes by 1%. A high M-value means a greater capacity to buffer RH changes. ART SORB outperforms ordinary silica gels, actually increasing its M-value (see Table 1).

Table 1: EMC/RH amd M-Values of Respective Silica Gels*

 

regular density silica gel

medium density silica gel

ART SORB

% RH

EMC

M

EMC

M

EMC

M
0

7.0 2.0 0   6.5
10 7.0 7.0 2.0 1.0 6.5 5.0
20 14.0 6.5 3.0 1.0 11.5 4.5
30 20.5 4.5 4.0 1.0 16.0 6.0
40 25.0 3.5 5.0 1.5 22.0 4.0
50 28.5 2.0 6.5 1.5 26.0 9.0
60 30.5 1.5 8.0 1.5 35.0 19.0
70 32.0 1.0 11.0 6.0 54.0 13.0
80 33.0 1.0 17.0 15.5 67.0 7.0
90 34.0 1.0 32.5 61.0 74.0 6.0
100 35.0   93.5   80.0  

*Data supplied by manufacturer or taken from S. Weintraub: "Studies on the behaviour of RH within an Exhibition Case", ICOM Committee for Conservation, Triennal Meeting, Ottawa, 1981, p. 81/18/4-1ff. ART SORB values change slightly from lot to lot.

Minimal Hysteresis Problems

Hysteresis is the phenomenon whereby a silica gel’s EMC/RH adsorption curve lies below its desorption curve (which drastically restricts a silica gel’s buffering ability). ART SORB has high slopes of both adsorption and desorption throughout the RH range, so it is not significantly affected by hysteresis. (see Figure 2), Hysteresis affects "regular density" silica gels to such an extent that their average M-Values along the adsorption / desorption curve (the values that represent the true buffering ability of a sorbent) are greatly reduced.

Figure 2: ART SORB Ad-Desorption Curve (at 25°C):

Immune to Temperature Change:

Many moisture sensitive materials are affected by temperature, causing M-Value and response time to vary adversely to temperature changes. ART SORB’s EMC/RH curve is largely independent of temperature changes. Of course, ART SORB has to be at the same temperature as the air in the showcase.

Economical:

Due to its extraordinarily high M-Value, especially between 40 % and 75% RH (the range which is most important for the conservation of most art objects) ART SORB has a large moisture reservoir to buffer changes in RH. Therefore ART SORB is much more economical in use than other buffering agents.

Adsorption of contaminants:

Like other silica gels, ART SORB is capable of adsorbing small quantities of organic volatiles. However, these compounds are not fixed irreversibly but can be released again when ART SORB is adsorbing additional moisture. Thus, contaminants might be transfered from one showcase to another. For this reason, ART SORB can not be rented or taken back.

Life span: 

Life span of ART SORB is not without limits. Like all silica gels, ART SORB is slowly losing its adsorption capacity. Presence of gazeous pollutants like acetic acid accellerate the degradation process. Our own experience is that the conditioning of an ART SORB cassette RH 50% typically rises by 1 - 1,5 % RH / year - at the same weight of the cassette. So the life span of ART SORB can be considered ± 10 years. You can continue using ART SORB much longer, but adsorption characteristics will be considerably lower.  

Precautions: see our page: "How to use ART SORB for the Preservation of Art". Further Informations see  Material Safety Data Sheet..

Prices

ART SORB beads, cassettes and sachets are only delivered pre-conditioned at 65 - 75% RH, ART SORB sheets only conditioned to RH 50%.

ART SORB beads, regardless the quantity and the conditioning , price per kilo
84,00 €
ART SORB cassette 750 g, 333 x 110 x 43 mm, Material: PP
68,00 €
ART SORB cassette 400 g,  333 x 110 x 24 mm,  Material: PP
38,60 €
ART SORB standard sachet 400 g, 350 x 150 x 20 mm, Material: one side TYVEK 1073 (dustproof) one side LDPE 35,10 €
ART SORB customized sachets up to 350 x 350 mm, price excl. filling. Material: one side TYVEK 1073 (dustproof) one side LDPE 4,50 €
Bestellen

ART SORB sheets
500 x 500 x 1,8 mm, 100 g dry gel/sheet, conditioned to RH 50% (according to the producer, we don't verify!)

 
1 sheet
30,- €
10 sheets
290,- €
20 sheets
560,- €
100 sheets
2700,- €
The sheets come sealed in aluminum film  
Order

Terms of sales and delivery

Products on stock are usually sent out within one week. Nevertheless, please order as early as possible. Transport is normally by FedEx Economy (±2-3 days within Europe), carriage is charged according to weight, dimensions and number of parcels.
All prices are exclusive VAT. Payments can be made within 30 days by bank transfer, within 14 days with 3% discount. All prices are subject to change without prior notice according to our terms and conditions. Check our website for actual information.

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Long Life for Art | Christoph Waller | Hauptstr. 47 | D-79356 Eichstetten | Tel. +49(0) 7663 608 99-0 | Fax -20
E-Mail: info@llfa.de, Web: www.llfa.de, © c.waller