Gamblin Conservation Colors

Ulrik Runeberg <rune-ulrik [at] gmx__de> writes

>My general impression is that certain colours work better than
>others: Burnt Sienna, for instance, represented an inpainting colour
>with similar characteristics to oil colour, and only after being
>diluted several times with pure gum spirits of turpentine, a glossy
>brilliance appeared which made further retouchings impossible due to
>the shininess of the retouching medium. On the other hand I observed
>that such pigments as Venetian Red possess that glossiness right
>from the beginning, before even being diluted. This brilliance even
>could not be reduced after stirring the colour well.

Several additional points regarding Gamblin Conservation Colors:

    1.  These paints are not stabilized and will therefore separate
        in the jar, with a layer of medium rich material on top. The
        colors can be remixed to restore the original pigment/binder
        proportions throughout.  But it is often more satisfactory
        to dig into the paint below to obtain less saturated
        pigment. This will form a less glossy film on the painted
        surface that can be glazed or varnished to effect the proper
        gloss.  In fact, it is my opinion based on the preparation
        of inpainting colors over many years that they should be
        made with a minimum of binder (less than might be used to
        produce artist's paints, for instance) with the intention of
        adding medium as needed during application to effect the
        desired gloss.

    2.  The use of turpentine is contraindicated if you want to
        reduce gloss. Turpentine's oiliness and slow evaporation
        promote flow and leveling during drying, resulting in
        maximum gloss.  A fast evaporating solvent like isopropanol
        will yield a matter surface with the same paint.  On the
        other hand, as with watercolors, the more polar the solvent
        you use, the greater the color change you will observe upon
        the drying of the paint.

    3.  The use of turpentine would seem to be contraindicated with
        Gamblin Conservation Colors as impurities and/or undesirable
        compounds that come over with the distillation may reduce
        the stability of the resin binder.  Unlike good petroleum
        distillates, turpentine, even highly rectified (i.e. Winsor
        and Newton), is not entirely volatile.  The materials left
        behind are known to contribute to the accelerated
        deterioration, especially discoloration, of other resins. It
        does not make sense to introduce these materials into an
        otherwise (relatively) stable material.


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                  Conservation DistList Instance 18:17
                 Distributed: Thursday, October 7, 2004
                       Message Id: cdl-18-17-007
                                  ***