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I've toyed around with the Tamiya Buff/dusting thing, but I'm having problems. Half the time I end up with a white residue splotched all over the model. I have not figured out what's causing it. It's just Tamiya Buff, Clear and thinner, right? Maybe water is getting into the mix?
Anthony, depending on how heavy you want the dusting will dictate how much you thin the Buff. I use either Tamiya thinner or isopropyl alcohol as a thinner. My SWMBO is a decorative artist and was the the one that developed and showed me the technique. She experimented on an older build of mine while developing the method. Here's an example of what can be achieved.
While the picture may not make it obvious, there is not only Tamiya Buff involved in the dusting but also XF-52 dark earth and several other artist acrylic colours from the Delta Ceramcoat range (Burnt Sienna, as well as various browns and ochre/beiges). The colours are diluted and applied with pieces of sponge from a decorative artist's stencil sponge.
The sponge on the right has been the donor for several weathering applications. You break off a piece of the sponge about 3/16 of an inch in size and use a reverse action tweezers to hold it and act as a handle. Depending on the intensity you desire you might blot the sponge on a paper towel before applying it to the model. BTW, a light touch/hand is a definite asset when using this technique.
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Hope this helps!
Cheers,
tread_geek