Sunshine and Shellac don't mix

Fnished a hall table over the long weekend out of recycled Oregan. Used the Shellac/Wax finish. Being extremely impatient, I had the bright idea that if I put the item out into the hot Sydney sunshine (Monday) the Shellac (3 coats) would harden quicker, so I could finish with 0000 steel wool and wax, rather than wait till the morrow.

Bad idea, Shellac started to bubble up, in tiny pinpricks. Took out of sun, and it stopped. Made for more sanding and shellac.

Just a warning in the unlikely event there is anyone else out there as impatiently stupid as myself.

Bodgy,

Thanks for the update, however I have a reciprocal question. Does shellac bubble only in extreme heat whilst its going off or can I expect any furniture that I finish to bubble up on a hot day ? I'd hate to finish a whole blanket box (see previous posts) and have the bastard bubble up once its got blankets in it!!!

Some advice is appreciated here - my intention on the blanket box was to piant on some ubeaut dewaxed white shellac with a brush, let it set for 10 mins or so then cut back with some ubeaut eee ultrashine .. is that the correct technique ?

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Originally Posted by Bodgy

Fnished a hall table over the long weekend out of recycled Oregan. Used the Shellac/Wax finish. Being extremely impatient, I had the bright idea that if I put the item out into the hot Sydney sunshine (Monday) the Shellac (3 coats) would harden quicker, so I could finish with 0000 steel wool and wax, rather than wait till the morrow.

Bad idea, Shellac started to bubble up, in tiny pinpricks. Took out of sun, and it stopped. Made for more sanding and shellac.

Just a warning in the unlikely event there is anyone else out there as impatiently stupid as myself.

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One of the main reasons I use shellac is because I'm an impatient bugger too and it dries as fast as it goes on. Mate, you must be the most impatient person I've ever heard of ! :D :D

Oh well, a project stuffed up is a lesson learnt ;)

Shellac is unfortunately the worst thing to put on a surface if you intend to have heat around. It is the material that is used for french polishing so you may have noticed that grandma's table always had a plate glass top or she put down placemats when ever you had Christmas dinner. Any hot cup or plate will mark it.

Don't put any paint finish in direct sunlight or put it close to a heater as the timber acts as an insulator and all the heat is transfered to the coating, at the same time air in the paws of the timber expand and blow up the finish producing the bubbles.

You can use shellac for finishing as long as its inside and away from the sun. Often its used to seal off timber before applying other paint but the same rules apply, keep heat away from the wood.

As metho is used to dissolve it and it evaporates quick it will dry as long as the temperature of the air is not freezing.

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Originally Posted by Gumby

One of the main reasons I use shellac is because I'm an impatient bugger too and it dries as fast as it goes on. Mate, you must be the most impatient person I've ever heard of ! :D :D

Oh well, a project stuffed up is a lesson learnt ;)

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Gumby

Yea, one of the advantages is that it dries very quickly, but the Ubeaut URL says to leave it overnight before polishing.

I did manage to rescue things a bit, just went back with metho and sort of massaged the bubbles out - in the shed with a fan going!

Durwood seems to be on top of things, I seem to remember Great Aunts making a fuss about no tea cups etc on the French Polished table, and earning a lift under the ear for transgression.

In terms of impatience, yes I do get a little itchy. Can't wait. Too much to do. Wouldn't queue up for even a night with Naomi Campbell.......um, er, well, not if it was a long queue anyway.

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Originally Posted by Bodgy

Wouldn't queue up for even a night with Naomi Campbell........

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:confused: :confused: :confused: :confused: :confused:

why would you bother ????? I'll stick with me missus thanks....

back to topic,

so if I paint on dewaxed shellac with a brush, let it set then polish off with eee wax i'll be ok so long as I dont put a coffee cup on it ?

Or should I use a clear polyurethane or something else instead ???

Dont use polly.:eek:

I just brush on shellac, best finish ever, dries in no time flat.
Looks good too.

Al :)

Wow thanks for the advice!

I had just laid two side table tops coated in shellac in the sunshine to speed dry when I was reading your post. I had the same idea (speeding up drying so I could buff today and have finished by tonight). Needless to say I sprinted outside to find two warm shiny surfaces with no bubbles.


There is a God!

That air bubble thingy is a problem I've observed with a few different finishes .
With my limited shellac experience I've found a really thin (25/75) coat or 2 first to get in to the pores and displace the air helps (mostly) , before going on to a thicker (50/50) mix for the remaining coats . my only complaint is due to my lack of painting skills I always have to sand back the whole piece with wet and dry once hard (600 generally , does that sound too ruff ?). comes up a treat with a quick wax polish afterwards , great for someone with all my (lack of) painting skills !:)

I found 800 really good for sanding back u-beaut's white shellac. Note this was on Kwila which is a very open-grained timber. 1500 didn't work well at all - which was Very interesting to note.

Neil's Finishing Handbook is Fantastic - well worth the money.

cheers
RufflyRustic

OK... to clarify the issue: When shellac is plastered over earlier coats, the upper coat sort of partially melts into the layer below it; so we don't have "coats" we have "A" coat of shellac. And the effect is graduated meaning the dryest, thinnest coats of shellac at one end of the spectrum vs. the wettest, thickest and freshest coats of shellac at the other OK to the science. From the fresh porous timber filled with air, to the remaining alcohol in the bottom of the shellac layer, to the DRYING skin on the outside of the shellac layer..... When the shellac is especially fresh, and deep, meaning kind of gooey and fairly saturated with alcohol and quite plastic.... usually from painting on heaps of thick coats of thick shellac, with a big brush.... WHEN the timber is stuck into the HOT sun..... The outer shellac skins... The alcohol underneath - in the timber and shellac layer, and the air in the timber pores - all heat up, start gassing and up come a heap of gas bubbles - under the jolly skin; kind of like a balloon of cling wrap... I LOVE slapping on the shellac with a BIG thick brush... BUT the SLOW drying is the go. I assume that 50 thin coats, take the same time to apply and dry as one coat 50 thin layers thick..... Hmmmmmmmm much less rooting around tho. Oh well back to standing on my head and waxing my foo-foo.