Finishing suggestions for punky rustic turned bowl

Hi All,
Helped a friend by cutting down some old dead wattles, grabbed a few pieces to mess about with.
I've made some rustic candleholders OK, and just used spray-on semigloss "conformal coating" (i get it cheap).

Not sure what kind of wattle, but fairly tall and thin tree, low density creamy timber, with nice spalting features, and a bit of punky timber as well.

I've just now done a rustic bowl from a piece of hollow log. It has internal "features" where the termites have eaten out the middle, and external features with the natural rought outer surface, and some "mini burls" . because of the "rustic nature" I can't apply any finish while on the lathe, I've sanded it back to ~400 grits, and the punky bits aren't too bad.
Problem is, I have tried my usual "conformal coating" (an alchohol based acrylic coating in a spray can ), but the end grain just sucks it up like a sponge (especially the punky end grain), while the denser burls create shiny puddles.

Is there some kind of sealer I should have used first ?
Is there some other kind of coating I could use? (maybe the Cabots crystal clear, or an estapol product)? I've use Cabots water based products on low density softwood on furniture, it seemed to form a skin, and it seemed to fill the grain so that the third coat was consistent.

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Originally Posted by salbay

Problem is, I have tried my usual "conformal coating" (an alchohol based acrylic coating in a spray can ), but the end grain just sucks it up like a sponge (especially the punky end grain), while the denser burls create shiny puddles.

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Have you tried giving it a second coat after the first had more than adequate time to properly dry? In principle, at least, once what has been 'sucked up' has set then subsequent coats should be OK. In practice, the next coat or two would probably also 'suck up...' but each to a lesser degree, until the later coats go on fine.

BTW, by properly dry I don't just mean touch-dry. I mean, a couple of days cure time so the finish polymerises. This'll minimise the degree with which the solvent from the next coat will dissolve the prior coat.

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Is there some kind of sealer I should have used first ?

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Dilute shellac works well for me. I lather it on, wait for it to dry off and then lightly sand all evidence of the shellac from the surface. Again, this may take me a couple of applications before the end grain stops soaking everything. But shellac is cheap and metho even more so. As a further bonus, it's quick to get multiple sealing coats on with. :)

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Is there some other kind of coating I could use? (maybe the Cabots crystal clear, or an estapol product)? I've use Cabots water based products on low density softwood on furniture, it seemed to form a skin, and it seemed to fill the grain so that the third coat was consistent.

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Having started with an alcohol based acrylic, you'll probably get best results by persisting with it.

Thanks for that, the product I am using is intended for printed circuit boards, typically with those, if you coat them outside in the sun (at 35C temp) very fast to get 3 thick coats on, and a couple of hours in the sun and the coating is very hard. The coating is easily soluble in alcohol, so in a decades time if the boards need rework, quite easy to dissolve and brush off the coating. The conformal coating behaves just like shellac. The product in the aerosol can is thinned for spraying so would behave like shellac thinned with metho. I also have the undiluted product in a can , it is quite thick, can be brushed or syringed on.
Yesterday was around 44C So I couldn't put the bowl out in the sun as it would have split, today I might have another go at getting some coating on, and I'll try to wipe off the shiny spots with a cotton cloth damped with alcohol. Then harden in sun, then sand off next day, and try a final coat.
The problem with this bowl is the jagged edge, so I can't use cloths while spinning on the lathe as it will grab them. I can use my bowl sander, with care, it tends to shred the edge of the disk a bit.

It won't help with applying the finish, but for sanding ragged edges on the lathe a worn-out thong (as in flip-flop!) as a rubber for cloth-backed sandpaper works wonders.

You do need to be careful not to round over the leading edges of the bowl, though.

Thanks for the thong tip! I've been wrapping sandpaper around foam sanding blocks, but they tear easily!
A great use for broken thongs.

Sprayed another coat today after waiting overnight, this coat doesn't seem to have sucked in !

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