Thread: How to allow for panel movement with a varnish finish

I would do the same as you have been doing for oil finished panels; varnish first and then assemble. If you varnish the frame after assembly then completely mask off the panel so you don't get varnish drawn into the joints between them.

Thanks, Chief Tiff, but I am worried that, even with masking, the varnish would still creep into the join? But this may be my only option.

Originally Posted by 3 toed sloth

Thanks, Chief Tiff, but I am worried that, even with masking, the varnish would still creep into the join? But this may be my only option.

I'd pre-finish (varnish) the panel and the frame separately before assembly.

Roy

Thanks Roy, that's another possibility, I've never glued up prefinished components before, so if I do that how do you go with glue squeeze-out?

Also, does the glue (titebond) still work on a varnished surface as opposed to bare wood? Now I think about it, it may not be critical anyway as the joints between legs and rails are all dowelled anyway, and I read somewhere that the bond between the end grain of the rail and the side of the leg doesn't lend any real strength to a dowelled joint.

So maybe the only issue with prefinishing is squeeze-out.

Originally Posted by 3 toed sloth

Thanks Roy, that's another possibility, I've never glued up prefinished components before, so if I do that how do you go with glue squeeze-out?

Also, does the glue (titebond) still work on a varnished surface as opposed to bare wood? Now I think about it, it may not be critical anyway as the joints between legs and rails are all dowelled anyway, and I read somewhere that the bond between the end grain of the rail and the side of the leg doesn't lend any real strength to a dowelled joint.

So maybe the only issue with prefinishing is squeeze-out.

If you put the panel into a dado instead of a rebate, you'd only have to glue a little area in the middle of the end grain ends of the panel. If you glued the panel into the dado or rebate completely, you'll likely have a problem with the panel tearing the frame joints apart in the future when the moisture content of the panel changes. If you glued the panel in a dado (with a mm or two of clearance all round the panel to allow for expansion of the solid timber panel), with say 25mm of glue in the middle of the end grain ends of the panel, the panel would still be able to expand and contract across the panel without tearing the frame apart. The glue would only be necessary to stop the panel from rattling in the frame. (A bit like making a frame & panel door.)

Titebond or any other PVA won't like gluing to a prefinished surface. When prefinishing, mask off the areas of tenons, mortices, rebates, dados, etc (anything that will be glued), to prevent the finish contaminating the joints. You normally clean-up PVA glue squeeze-out (before it fully sets) using a damp rag. A Poly Varnish won't be adversely effected by water, so using a damp rag to clean off the fresh glue squeeze-out should not be a problem.

Regards,

Roy

OK, thanks Roy, that all makes sense. I should have said dado instead of rebate, I always get them mixed up. Anyway it's a groove 6mm wide by 8mm deep.

Looks like I'm going with pre-finishing, then Christmas eve glue-up, for hand over Christmas day...what could possibly go wrong?

Just read over my info. on varnishing, and realised I don't have time to do it properly before Christmas. So now i'm going with shellac which I really like as a finish anyway, and it dries a lot quicker. Still going with the pre-finishing.

Thanks for the interest and help.

Peter

Originally Posted by 3 toed sloth

Just read over my info. on varnishing, and realised I don't have time to do it properly before Christmas. So now i'm going with shellac which I really like as a finish anyway, and it dries a lot quicker. Still going with the pre-finishing.

Thanks for the interest and help.

Peter

Peter,

It's a pity you don't have enough time to finish the drinks trolley in a Poly varnish, as I'm fairly sure that Shellac will not be a very durable finish on a drinks trolley. The first time you get a bit tipsy and spill some whisky, vodka, rum (and probably most other alcohols) the shellac is going to lift. Maybe a good few coat of furniture wax regularly might help resist any alcohol spills.....as long as the spills are mopped up and dried promptly.

Alternatively, for a project like the drinks trolley a Lacquer finish would be more durable to alcohol spills (not as durable as a polyurethane varnish, but better). For a relatively small project like a drinks trolley, clear Lacquer in Pressure Pack Cans would probably not be too expensive (unless you've got the spray gear to be able to spray the liquid Lacquer), and it's even quicker than shellac to apply, and re-coat. I got some pressure pack cans of Clear Lacquer from a car finishing supplies place last time I needed some for a few presentation boxes - price was under $10.00 for a 300ml can - I think from memory it was Dulux brand. Unfortunately, as it's designed for the automotive market, it is only available in gloss. The stuff is meant for DIY touch-up of car paint jobs, but it does a beaut job on woodwork projects. Wear a suitable mask ! It is nasty stuff if you breath it. I sprayed it outdoors early one morning before the breeze got up, and the results were good, and because it dries so quickly, there was very little opportunity for dust or anything else to get on the wet surface.

Regards,

Roy

Originally Posted by 3 toed sloth

....Looks like I'm going with pre-finishing, then Christmas eve glue-up, for hand over Christmas day...what could possibly go wrong?

Not very tight schedule you set your self.

Originally Posted by 3 toed sloth

Just read over my info. on varnishing, and realised I don't have time to do it properly before Christmas. So now i'm going with shellac which I really like as a finish anyway, and it dries a lot quicker. Still going with the pre-finishing.......

I am not sure on the Shellac, unless you are thinking of Hard Shellac from our forum sponsor. I have used it once on a piece but not on a usable piece more just for show, I think it was a clock that I made.

Thanks for those comments gents, I understand your concerns.

It really comes down to the fact I've got shellac in the shed and no time to get anything else, and I can't experiment with something different at this stage.

Although it's a drinks trolley, it will probably spend 99% of it's life holding up a couple of ornaments as it's for the MIL, so it's for show as much as anything. At least, as it's staying "in the family", I can do an easy repair job on the shellac if needed.

Hi Christos, I have tried hard shellac, but I didn't do a very good job, again I think I'd need to practice a bit to get it right, so I'm just hoping everything will be okay, and at least it will be finished in time (hopefully) and it will look good on the day.

Just wondering if you got your Drinks Trolley finished in time - and how did the Shellac finish go ?

Regards,

Roy

Yes, Roy, just got there, finished waxing around 6:30pm Christmas eve. Mother in law was very happy with the result. Trolley was used on the day, mainly for the excess of soft drink bottles the kids bring along which won't fit in the fridge.

Later on it was put aside with a few nice ornaments on top and looked really good there. I've added a few photos of the finished product, timber is Tassie Blackwood.

I wonder whether this sort of thing would be better done with veneered panels, as you wouldn't need to allow for movement and the panels could be glued in place, giving the thing a lot more strength, although you would have to be very accurate to avoid gaps. Maybe the panels could be dropped in after the frame is glued up?

Cheers, and Merry Christmas, Peter

Peter,

Great job ! That drink's trolley looks really nice.

Congratulations........

Roy

At least you were not trying to finish this on the morning of Christmas Day.

I would have expected one other person working on Christmas Eve.