B72 Retouching Gels
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Please send your questions regarding the use and properties of B72 Retouching Gels.
 

Q: Are the B72 Retouching Gels compatible with resins used for  retouching/inpainting other than Paraloid B72 (Acryloid B72)?

Q: I use Paraloid B72 (Acryloid B72) solutions in xylene and Shellsol 100, can they be used together with B72 Retouching Gels?

Q: What solvents can I use with B72 Retouching Gels and where can I buy them?

Q: Can the drying of the retouching/inpainting carried out with B72 Retouching Gels be speeded up by blowing hot air with a hair drier?

Q: Retouching carried out with B72 Retouching Gels cracks upon drying.

Q: Dry paint has a rough, gritty surface.

Q: Are the B72 Retouching Gels stable and reversible?

Q: Glazes made with B72 Retouching Gels are not visible in UV light.

Q: What is the shelf life of B72 Retouching Gels?


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Q: Are the B72 Retouching Gels compatible with solutions of resins, other than Paraloid B72 (Acryloid B72), used for retouching/inpainting?

A:
B72 Retouching Gels can be used and mixed together with solutions of polyvinyl acetate in Industrial Methylated Spirit or propylene glycol ethers. The use of other resins commonly used in retouching media is not recommended.

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Q: I use Paraloid B72 (Acryloid B72) solutions in xylene and Shellsol 100, can they be used together with B72 Retouching Gels?

A:
The use of xylene, Shellsol 100 and other aromatic hydrocarbons is not recommended with B72 Retouching Gels. Nonpolar solvents interfere with the liquid crystal phase of the Gels.

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Q: What solvents can I use with B72 Retouching Gels and where can I buy them?

A:
Three solvents originally used in the Gels are recommended. One can limit the range of solvents to Dowanol PM (1-methoxy-2-Propanol) but then after repetitive diluting the Slow Gels will become Fast Gels. Industrial Methylated Spirit can be used with the Gels in order to increase the fluidity of paint. Isopropanol (propanol-2-ol) cannot be used.
The solvents can be purchased from Sigma-Aldrich Company

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Q: Can the drying of the retouching/inpainting carried out with B72 Retouching Gels be speeded up by blowing hot air with a hair drier?

A:
The paint applied in a thin layer can be dried by blowing hot air with a hair drier. Drying by heat is not recommended in the case of freshly applied, very high impastos. See Palette Knife painting.

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Q: Retouching carried out with B72 Retouching Gels cracks upon drying.

A:
Paint made with Light and Very Light gels will crack if it is applied in thick layers. If a thick layer of paint is required, or texture, or impastos, the use of Heavy gels is recommended. See Cracks.
Paint also may crack if the first layer is painted with Slow or Very Slow gel and then overpainted, before it is completely, dry with Fast drying gel. This does not apply to thinly painted layers and to painting glazes wet-in-wet.

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Q: Dry paint has a rough, gritty surface.

A:
Because of the high viscosity of the gels special attention has to be paid to the proper dispersion of pigments in the medium. Paint containing agglomerates of pigment particles will dry with a rough surface. Such a result can be avoided by grinding pigment with gel for longer and more vigorously or by premixing pigments with a standard solution of Paraloid B72 or solvent.

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Q: Are the B72 Retouching Gels stable and reversible?

A:
B72 Retouching Gels are made of Paraloid B72, one of the most stable modern polymers which has been extensively tested for use in conservation and restoration. They also contain HALS (hindered amine light stabiliser). Gels with a large proportion of fumed silica are more difficult to redissolve because of the silica content.

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Q: Glazes made with B72 Retouching Gels are not visible in UV light.

A:
The visibility of the glaze in ultraviolet light depends on the concentration of pigment. Glazes with low pigment concentration may not be visible. Particles of pigment applied with gel are separated by liquid crystal. This leaves gaps between them in the dry glaze. The gaps allow the UV light to penetrate to the original paint layer and its fluorescence to be visible.

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Q: What is the shelf life of B72 Retouching Gels?
A:
The shelf life of B72 Retouching Gels is practically infinite so long as the jar lids are tightly replaced.

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