Sanding between coats dust nibs or uniform scratch pattern?

[Tetsuaiga]

I was wondering what people's thoughts are about this.

Should I sand so there is no sheen left anywhere and the whole surface is regulsr or just till its smooth to the touch and removed any dust nibs?

I'm using polyurethane at the moment but also use regular oil varnishes.

 

[ED65]

Nibs and other imperfections only, there's no need to get a uniform scratch pattern. I suppose the most enduring myth is that it's necessary to ensure a good bond but as long as you're within the recoat window it isn't.

BTW technically polyurethane is a 'regular oil varnish' as they're just alkyd with a little polyurethane mixed in. In terms of bonding (to itself) there's no difference.

 

[Tetsuaiga]

The only thing I was thinking if that if there are imperfections due to application, I wipe mine on, so there might be minor streak marks or uneven deposit won't they show through after the next coat is laid down.

 

[ED65]

You shouldn't see the difference between sanded areas and unsanded after the next coat has dried, not unless it was very thin (thinner than it probably should be).

The grit you use to denib obviously matters because if the scratches are a little too big wiping varnish won't be able to obscure them on the next coat. So you shouldn't use the same grit you last sanded the wood at, anything from 150 to 240 is a little coarse. I can't remember offhand what Bob Flexner recommends but if memory serves it's 320, which is approximately the same as P400, although others go even finer.

Best plan is to try some tests and see what you get with what you're using.

 

[Tetsuaiga]

Well interestingly it does seem that the minor variances in appearance I mentioned do seem to have disappeared after the next coat. Seems its okay to just do the denibbing and any other really obvious problems.

Thanks for your replies.