shellac rubbing out slightly cloudy

[kay gree]

hey millers.

been lurking here a short while, was hoping not to post and just learn by reading, but I think I've finally ran into a problem I haven't seen anyone bring up before.

this is a walnut slab being finished in shellac, but as always a picture is worth a thousand words so:
IMG_0646.jpg

there is a 'finished' (meaning flat, rubbed out to gloss) section in the middle that looks slightly opaque/cloudy. It's surrounded by fresh, unflattened/rubbed shellac which looks much more vibrant in color.

my schedule: flatten after shellac application with 220, 320, 400, 600; then polish with 1000, 2000, 4000. This is using mirka abranet and abralon with a festool ro150. Otherwise, this is bt&c super blonde shellac dissolved in pure ethanol on oregon black walnut from goby walnut in temperate, non humid san francisco bay area weather. The slab was sanded though to 320, then oiled with tried and true danish oil, followed by a pore filling using the same oil and sawdust from 320 and 500 to make the 'slurry'.


any thoughts? all insight appreciated.

[Kent A Bathurst]

Are you all the way though the shellac rubout schedule?

When in that schedule did this problem first catch your attention?

I am going to guess that there is a layer of something down there that did not reach full cure before the shellac started being applied. Did you wipe everything down with, say, MS after the filling but before the shellac? Did sand and/or wipe down for dust between shellac coats? With what?

[kay gree]

Kent, I would say I'm done with the rubout schedule at 4000 grit. I could take it one more step with rottenstone, but that gets messy and the cleanup of the mineral oil with naphtha makes me feel slightly uneasy (I feel naphtha is just another solvent for shellac, albeit a poor one).

I would say the problem didn't catch my eye until I put down the fresh shellac right next to it. I wasn't entirely happy with the look I was getting, but nothing was obviously wrong as the opaqueness is uniform across the slab.

I didn't wipe with spirits or anything else after pore filling. I did let it rest for a few days. Just dry dusting between coats, no sanding as shellac appears to adhere to itself just fine, no need for a tooth.


the niggling thought I'm entertaining is that it's cloudy simply because 4000 grit abralon is still optically 'rough'---maybe I do need to use a polishing compound or suck it up and get dirty with rottenstone.