Quantcast
  • We invite you to join UKWorkshop.
    Members can turn off viewing Ads!

shellac finish?

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

sunnybob

wysiwyg
Joined
11 Oct 2014
Messages
8,399
Reaction score
157
Location
cyprus
I'm getting quite adventursome now, I've just made a garden coffee table that actually has JOINTS in the base :shock: :shock:
(its a garden table because those joints would not be allowed inside, but hey, they're better than the last ones I made when I was 12))
But I am not getting a good finish with the (new to me) shellac.
The edge of the top is in maple. I sand it smooth to 320 grit, and brush on thin shellac. the first coat dries almost at once.
The second coat takes a little longer.
But once dry, the maple now feels like I sanded with 80 grit?
So I sand that surface down to 400 grit and apply another coat.
When its wet it gleams, but when it dries it STILL dries like 80 grit.
What am I doing wrong please?
 

CHJ

Established Member
Joined
31 Dec 2004
Messages
20,131
Reaction score
67
Location
Cotswolds UK
Are you wiping the sanded surface down with a tack cloth to remove dust debris?

(Or wet wipe with spirits if you don't have tack cloth)
 

profchris

Established Member
Joined
14 Jun 2015
Messages
777
Reaction score
52
Location
Suffolk
That's what I get with shellac too, though I wipe on thin coats. I think it raises the grain slightly, and because the coat is so thin it feels rough.

If you sand back thoroughly you expose more wood fibres, so you're nearly back to stage 1.

What I do is to sand back to smooth after coat 1, sand back less aggressively after coat 2, and thereafter I do little more than dust the surface with my fine abrasive, just enough to remove any roughness. After about coat 4 or 5 all is smooth.

Shellac goes on in really thin coats so you need lots of them - on a ukulele I might apply a dozen wiped on coats in total and get a film thickness that's maybe as thick as a sheet of copier paper, maybe even less. But they go on and dry really fast - on a UK summer's day I might apply 6 coats, in Cyprus you might apply all 12!

A thicker cut builds faster but dries a lot slower, and if you apply the next coat before the previous is fully dry you can get problems, with the finish producing sticky patches and distortions. Lots of thin coats is what works for me, and it's pretty much foolproof.

So it's both slow and quick, paradoxically. I'd guess brushing one thin coat onto a coffee table top takes 2 or 3 minutes, and then the same to dust it with abrasive once it's dry. So 72 minutes to apply 12 coats, but spread over 2 or 3 days.
 

Rorschach

Agent Provocateur
Joined
6 Jan 2016
Messages
3,906
Reaction score
159
Location
Devon
I tend to do a few coats and then knock it back with at least 320, usually higher. You don't want to sand through the shellac, just take off the roughness, it might take two or 3 light strokes at most, then add a couple more coats of shellac. You don't need to worry about providing a key for the shellac, just making it smooth.
 

sunnybob

wysiwyg
Joined
11 Oct 2014
Messages
8,399
Reaction score
157
Location
cyprus
I use a soft brush to remove dust before applying the shellac. Never actually seen a tack cloth.
When i start sanding again I start with 220, then 320, then 400.

I've gone up to 5 coats before and still dont get a really smooth finish. maybe i should try some 0000 wool?
 

sunnybob

wysiwyg
Joined
11 Oct 2014
Messages
8,399
Reaction score
157
Location
cyprus
No.
But I have sanded the shellac surface three times if that helps :roll: :roll:
 

profchris

Established Member
Joined
14 Jun 2015
Messages
777
Reaction score
52
Location
Suffolk
I reckon 5 coats is not even half way! If you scraped back to bare wood in one spot you'd see how thin the film is.
 

profchris

Established Member
Joined
14 Jun 2015
Messages
777
Reaction score
52
Location
Suffolk
This what a dozen coats looks like - you can get shinier with a few more and then buffing with rubbing compound.

Koa box.jpg
 

Attachments

sunnybob

wysiwyg
Joined
11 Oct 2014
Messages
8,399
Reaction score
157
Location
cyprus
Define rubbing compound?
I have metal polishing compound in three different grades.
 

profchris

Established Member
Joined
14 Jun 2015
Messages
777
Reaction score
52
Location
Suffolk
I use T-Cut automotive rubbing compound. I reckon metal polish would work well.

But leave it a couple of weeks to harden before you go down that route. I wet sand *very lightly* with P1,000 wet and dry, then the rubbing compound. Or sometimes I leave out the wet sanding. If you have no pores, or have pore filled, you can get a mirror finish by going increasingly fine with the rubbing compound. I stop when it's shiny enough for a musician :D

Don't forget it's a thin film, so don't go too wild!
 

profchris

Established Member
Joined
14 Jun 2015
Messages
777
Reaction score
52
Location
Suffolk
Oh, one more thing - an outside coffee table? Shellac is rather fragile for that - UK rain won't do it any good (but you're in Cyprus I think, maybe your rain is OK), and coffee mugs leave rings. And it's alcohol soluble, so wine and beer glasses are a danger. OTOH it's easy to repair.
 

sunnybob

wysiwyg
Joined
11 Oct 2014
Messages
8,399
Reaction score
157
Location
cyprus
I was concerned metal polishing compounds would blacken the wood, I'll have to try it on a scrap piece.
Its a one piece ceramic tile top, with maple edging, on a frame of ... emmm, construction timber :oops: :roll:
This is a learning exercise so I wasnt prepared to spend money on good quality hardwood that could so easily have gone straight to the scrap bin.
But it is under cover so rain should not be an issue (it will be raised off the floor for monsoon season)

I'll take all this under advisement for future projects where a gloss finish would be more appropriate.
Thanks all. =D> =D> =D>
 

xy mosian

Established Member
Joined
21 Feb 2009
Messages
2,805
Reaction score
2
Location
West Yorkshire
sunnybob":2qjeuxbm said:
No.
But I have sanded the shellac surface three times if that helps :roll: :roll:
I cannot answer that as I always raise the grain, with water, before applying a Shellac finish. That goes for many other finishes as well.
I suspect that raising the grain before hand might well have significantly reduced the snags you have come across.
xy
 

Latest posts

Top