|
NEVEK is a cleaning system based on the extractive and retaining properties of Agar-Agar, whose main feature is to form rigid gels, useful when you need to use water in thickened form.
Providing heat, the polysaccharide chains of Agar-Agar in aqueous dispersion are distributed randomly, giving a fluid solution, while with cooling they are being put in order, forming tubular structures that are responsible for the characteristic rigid gel, within which water molecules can move.
The gelation process can be reversed by heating and cooling indefinitely, and that is why we talk about thermoreversible gels.
The new NEVEK formulation allows to overcome the complexity in using Agar, increasing the applications and simplifying the procedures.
Fields of application
All restoration fields can be affected by the particular properties of this system, given that NEVEK can support both aqueous solutions and solvents, releasing them in a gradual and controlled way. Among the possible applications we mention the main ones:
Removal of dirt and residues of old glues and protective coatings from stone surfaces, plasters, murals, panel and canvas paintings, paper, wood, even polychrome, pottery, archaeological finds.
Extraction of salts from stone surfaces, mosaics, archaeological finds and wall paintings.
Removal of varnishes from wood, even polychrome, panel and canvas paintings and stone.
Moisture intake with high control of liquid water diffusion.
Advantages
NEVEK, strongly retains water, and can therefore be used for the removal of water-soluble substances present in the soiling deposits, as some salts, with a controlled intake of moisture. Water in fact wets the interface between the gel and the surface, by limiting the penetration into the porous structure of the material (plasters, stone materials, frescoes, paintings). Besides NEVEK also works like a sponge, absorbing the solubilized material.
It has some advantages compared to the classic rigid gel:
1. it is ready to use and does not require the preparation procedures of agar in powder (component weighing, solubilization and heating)
2. it has less adhesion and is particularly suitable for sensitive surfaces (in the presence of paint blisters, disgregations, heat sensitivity)
3. it is possible to add organic solvents, also apolar such as ligroin, creating a system that works like emulsions.
4. it can be used equally fluid; with heat, the thermoreversible gel is transformed into the liquefied state.
Application
The product is ready to use and can be applied as it is for the removal of water-soluble substances.
NEVEK is spread by hand or spatulas, and due to its thixotropic properties it can be also applied on vertical surfaces. Thanks to its structure, it adapts perfectly to all surfaces, even irregular, and is easy to remove, for example with a dry brush. The removal is further simplified by interposing a sheet of Japanese paper.
NEVEK can be heated in a microwave oven or in a bain-marie, obtaining a fluid phase that may be distributed on the surfaces with a brush and allowed to cool. In this way it reforms the gel that perfectly follows the roughness of the surface and absorbs the water soluble dirt. This is then mechanically removed by gently lifting the film from the center to the exterior, with the help of wooden sticks.
If necessary, the product can be modified by inserting substances which potentiate its activity, up to a maximum of 50% of the weight, using a simple mixer to uniformly incorporate them:
1. You can add aqueous solutions of surfactants, chelating agents, acids and bases as for other gels; the release of the solution and the effect of these substances will be restricted to the surface, by limiting the penetration in the underlying layers.
2. You can add solvents of various polarity to be evaluated by preliminary tests. Also in this case the release of the solvent in the underlying layers is limited.
The contact times, to be determined each time with evalutation tests, mainly depend on the type of substrate, the material to be removed, the environmental conditions, and how NEVEK has changed.
It is not necessary to rinse the surface, as the product does not leave residues.
Note: in case you add substances (solvents, chelating agents, etc.) the gel can no longer be heated.
Examples of application
Cleaning of plasters, stone surfaces and wall paintings:
The agar gels have long been used on plaster and stone material, also with the addition of additives such as surfactants and chelators.
The versatility of the cleaning system provides the instruments to develop the various methods able to adapt to the many problems encountered.
Removal of salts from stone material:
apply the product on the surface and remove after a few hours.You can enhance the effectiveness with the addition of complexing agents such as EDTA or ammonium citrate.
Preparation of a paint remover of low toxicity:
add to NEVEK an amount not more than 50% of the weight of solvents selected according to the type of paint to be removed, until you reach homogenity. Apply on the paint – time to be determined on a case-by-case basis, then remove mechanically the NEVEK film and the swollen paint.
Removal of old PVA layers from the back of a canvas:
add to NEVEK a 1: 1 mixture of acetone and ethyl alcohol, in an amount not exceeding 50%. Mix until you reach homogeneity. Apply on the Vinavil layer. After a few hours the swollen film lifts easily from the canvas, without that the solvents have entered into the underlying layers.
Storage
Packages must be carefully closed and stored at ambient temperature. Thanks to its composition NEVEK is not subject to microbiological degradation, in the original formulation.
Available per kilo
|
