I appreciate the mention! this one is on the way, just needs to fill out. did you use ink on the hollow, or burn it? either way, i would probably take a wire brush to it and dull it down at least so its not all one color. or just let time take its course. I never liked the look ink or fire gives to hollows tho, whenever i did apply ink i always ended up rubbing it out. the most convincing hollow are the deeper ones, where you dont need to apply anything, the depth already gives it that shadow if you know what i mean. but obviously we cant always go too deep on our trees, not all at once anyway.
see the depth on this one, you have one depth but then there are recessed walls, deeper areas and it appears to get darker as you look in. i did use some stain, then i burnt the stain and then i use a rotary brush to dull bits down so its more of a dark blemish, then i make the blemish darker as you go further in.
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using this on a dremel, allows you to dull down stain or burning, so you get more of a weathered looking grey