Mixing a neutral 'black' glaze - quick tip

I recently discovered the use of an ND (neutral density) filter as reference when mixing a neutral transparent glaze.

I needed to make some minor adjustments in some shadow areas without affecting the hue, and found no pigment that was both neutral in colour as well as transparent enough for subtle glazing. Then I saw my ND Filter on my desk, which gave me an idea. ND Filters are made to reduce light in photography without affecting colour and are completely grey to almost black in appearance. Mine are pretty dark, because I use them for long exposure during day time. A somewhat lighter one would be better for this purpose. Seeing that a glaze works pretty much in the same way than most optical filters, the ND filter served as an excellent reference to mix a neutral transparent glaze. The pigments that worked the best were Ultramarine and Vandyke Brown. I tried Burnt Umber; that however shifted towards green and never really became neutral.

This mixture is only neutral when used as a glaze and will shift towards blue when mixed with white, unless yellow is added, in which case Burnt umber would be the better choice.

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Stellar idea Peter!!! Thank you so much for sharing. I will definitely try this. :smiley:

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Hmm… interesting. Perhaps one could construct a shading series with such a tool.

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Which brand of Van ■■■■ Brown do you use? Also Tony, what about this mixture for black sinking it per the topic today? I also wonder about Caput Mortem but that might have too much purple. I was wondering, because I have used the combo of Alizarin/UB/Viridian (I accidentally wrote TOR instead of alizarin but some don’t like the fugitive nature of alizarin) for black to avoid sinking in which might be better than this higher value option?

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I also like Ultramarine Blue and Raw Umber (Old Holland).

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I honestly avoid mixtures with Ultramarine and Alizarin just as they are super thin. My go-to mix has long been Lamp Black and Raw Umber. I love it.

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