Using shellac varnish on oiled wood

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escuta
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Using shellac varnish on oiled wood

Post by escuta » Thu Jun 18, 2020 4:43 pm

Hello forum,

I'm a very occasional woodworker, having made two simple pieces of furniture only once before. For that first attempt (supports for two loudspeakers), I used a shellac varnish after having oiled the wood with linseed oil. While it worked out quite well, the varnish to this day (about 4 years later), remains a little sticky in places, especially in hot weather (30-38ºC).

I'd like to achieve the same look for the current project which is another support for a piece of equipment. I'd like though to get the varnish right.

I don't remember now how I went about doing the varnish. I would have left the oil soak into to the wood for a day, I imagine, and used scales to correctly measure the shellac flakes, which I mixed with a 96% ethanol.

What might have made it gone wrong? The oil? Besides using a synthetic varnish (which I don't want to do), what can I do to ensure that the varnish sets hard?

My plan is to again use linseed oil to darken the wood a little (a Brazilian hardwood called jequitibá) and then varnish with a 96% alcohol and shellac solution (100g shellac flakes per litre of alcohol).

I've posted a sketchup image of the project in the woodworking forum here, as I have a structural question too.

https://www.woodworkuk.co.uk/forum/view ... =4&t=14088

Thanks a lot, all the best,

Iain

woodsmith
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Re: Using shellac varnish on oiled wood

Post by woodsmith » Thu Jun 18, 2020 11:43 pm

I wouldn’t oil wood before using shellac but if you want to you will need to make sure the oil is completely dry before applying shellac. That means not applying the oil too thickly and leaving it a week or more to dry.
Keith

escuta
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Re: Using shellac varnish on oiled wood

Post by escuta » Fri Jun 19, 2020 11:18 am

woodsmith wrote:
Thu Jun 18, 2020 11:43 pm
I wouldn’t oil wood before using shellac but if you want to you will need to make sure the oil is completely dry before applying shellac. That means not applying the oil too thickly and leaving it a week or more to dry.
Thanks for the advice. I see, so the linseed oil was the probable cause. I try this project without oil then.

Re. my old project. If I remove the old varnish with alcohol and let it dry for a couple of days (or more time?), will a new coat of shellac set hard?

All the best,

Iain

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Re: Using shellac varnish on oiled wood

Post by 9fingers » Fri Jun 19, 2020 12:36 pm

Just leave it oiled and maybe just maybe try some wax if you must.

Bob
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woodsmith
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Re: Using shellac varnish on oiled wood

Post by woodsmith » Fri Jun 19, 2020 5:32 pm

escuta wrote:
Fri Jun 19, 2020 11:18 am
woodsmith wrote:
Thu Jun 18, 2020 11:43 pm
I wouldn’t oil wood before using shellac but if you want to you will need to make sure the oil is completely dry before applying shellac. That means not applying the oil too thickly and leaving it a week or more to dry.
Thanks for the advice. I see, so the linseed oil was the probable cause. I try this project without oil then.

Re. my old project. If I remove the old varnish with alcohol and let it dry for a couple of days (or more time?), will a new coat of shellac set hard?

All the best,

Iain
Yes it should be ok if you remove all the unset shellac. For the stand, shellac is going to be a difficult finish to work with. I would either use Finishing oil or Osmo Polyx. Linseed oil isn’t a particularly good finish for furniture and I wouldn’t use for your project
Keith

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Re: Using shellac varnish on oiled wood

Post by escuta » Fri Jun 19, 2020 6:04 pm

[/quote]
Yes it should be ok if you remove all the unset shellac. For the stand, shellac is going to be a difficult finish to work with. I would either use Finishing oil or Osmo Polyx. Linseed oil isn’t a particularly good finish for furniture and I wouldn’t use for your project
[/quote]

Thanks again Keith, I'll look these up.

Edit: would these products be applied in place of shellac or varnish, or before?

I thought I'd post photos of the wood I'm using for the stand and also the wood of the switchboard (oak?). I'd like to get the wood to a similar tone but it certainly doesn't have to be identical, though perhaps no darker or not too much so.

jequitibá.jpeg
oak.jpeg

thatsnotafestool
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Re: Using shellac varnish on oiled wood

Post by thatsnotafestool » Fri Jun 19, 2020 10:06 pm

Why would you ever want to put shellac over linseed oil ?

However, if you do want to carry on using linseed oil in future then just load your brush once and use it to cover the whole thing. Linseed oil HAS to be put on thinly. And even that is too thick. You also probably didn't let it dry enough before putting the shellac on. And use a rag ...not a brush..otherwise if you leave brush marks then two years later when you go back and rub the ridges, you'll find that it's still not dried underneath.

Other than that, it's great stuff. Especially outside. And on cricket bats.
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Re: Using shellac varnish on oiled wood

Post by woodsmith » Sat Jun 20, 2020 7:23 am

Finishing oil and Polyx are stand alone finishes that do not need any other product to be used with them. Now I see you are in Brazil I’m not sure what finishes are going to be available to you but it’s generally never a good idea to mix finishes. If you are trying to match a finish then use bits of scrap timber and try different ones until you find one you like.
Keith

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