How to recover from a poor shellac finish

[Dengue]

For the past 3 weeks I have been trying to finish a box with shellac, without any good results.

I have tried various mixtures of white dewaxed shellac and IMS without success. I have tried cotton rags, flanellette rags, and very fine camel hair brushes used for water painting.

I have tried thick coats, thing coats and just smears.

There are several layers of shellac, but I cannot get a good final layer - it either has brush marks, runs on the corner, or blisters.

in the interest of finishing this box by the required deadline, I think it is now time to give the shellac away, and apply some other finish over it.

Can anyone please advise a suitable finish that will go over shellac, preferably one that gives a nice satin or glossy finish e.g., Scandanavian Teak Oil, Tung Oil, Kunos Oil Sealer etc?. I doubt if any oil finish could be absorbed with all the shellac layers, although I notice on the can instructions that Wattyl Scandinavian Teak Oil is meant to be applied after a coat of polyurethane.

I would appreciate any ideas and suggestions

[AlexS]

Not sure why you're not getting a good result with the shellac, but if you're giving up on it, you should be able to sand it back (not completely off) and apply most sorts of oil.
I'd probably start with 240 or 320 grit, work up to 800 then clean off with white spirits or turps, than apply your oil. Kunos is my preference, but there are many which should be suitable.

[Dengue]

Thanks for this advice, Alex. How do you apply the Kunos?

I have just purchased the Kunos #244 finishing oil for my next project, so that is available now.

[surfdabbler]

Shellac will dissolve back off with spirits. I've given it a go a few times and had plenty of failures. I've also had some good success with sanding it smooth, and hitting it with steel wool and carnauba wax for a really nice satin-shellac finish, so you could give that a go too if you are happy with a satin finish.

[Xanthorrhoeas]

Its hard to beat a good shellac fininsh imho. Traditional shellac finish with very dilute button shellac applied in many fine layers with a rubber gives an excellent and long lasting, proven finish. The common problems are caused by not letting the layers dry enough before applying the next and having too wet a rubber (or brush) which leaves a pool or puddle of lquid and disolves all or most o the layers already laid down. Happily, the solution is simple -- wipe it off with metho and start again, with more patience.

If you have run out of time there are lots of instant finishes to try. Good luck but please don't abandon shellac for future projects. It may take patience but does give a wonderful and long-lasting finish that really enhances the fine figure of timber. Button shellac is a more natual product than orange flake shellac, which I do not like, personally. The so-called clear versions of shelac have been chemically modified so are not time proven like the traditional buttons.

[dr4g0nfly]

Possibly too late to try another shellac but how old is the stuff you've got.

It can have a remarkably short shelf life (6 months).

Also is it warm enough for the 'spirit' to evaporate off fully before you're trying the next coat?

[Dengue]

My bottle of dewaxed white shellac is about 6 months old, kept cool in a dark cupboard. I have allowed about 2 hours between coats, but here in the tropics it is not cold, daily temps 15 - 25 degC, except it will drop to 10degC tomorrow morning...brrrrr....

Suspect my problem is technique with the rag or brush.

With the rag, I pour thinned shellac ( 50% industrial metho) on to the flannelette rag , which eventually becomes wet all over, squeeze it in my fist to get it uniformly wet but not dripping, more like a wrung out damp dishcloth, then fold it into a 2 inch wide square and then wipe it firmly across the workpiece, starting just in from each edge like Neil shows at the end of the 4th video he posted (he used a brush). This results in a very thin smear.

The problem comes with the subsequent coats.

[Horsecroft88]

I read your post the other night and was somewhat puzzled but wasn't sure I could really add much that might help, but having read the further posts, including your last one, perhaps I might be able to give you some ideas to see if it works.

First off, I will admit I am a shellac-aholic, that being I won't use any other finish on antique furniture or joinery. Check out my post (albeit somewhat lengthy over on the restoration section). In this thread I give my take on the use of shellac, how to mix, how to apply and some of the problems you can encounter. There are plenty of pictures there.

First off, I will admit I have never used pre-mixed shellac (apart from the very first thing I re-polished some 20+ years ago). Secondly I have never used dewaxed white shellac, nor button shellac (have never even heard of this product). I unlike Xanthorreas love orange shellac. For me it produces exactly the finish and colour I am seeking and again I have no issues in mixing shellac flakes with metho. I don't even use special metho, just the normal stuff bought from Mitre 10, Bunnings etc. I do intend getting hold of some hard shellac as I think I have a use for a project or two for this.

Likewise even though I havn't got a copy of the polishers handbook from Ubeaut, for a novice in using shellac etc, I would definitely suggest this could be a good investment.

In terms of your box, first off a few questions. Was the box previously polished or in a raw state. This can make a difference in that if previously coated perhaps you are getting a reaction with a previous finish.

Secondly, I will say that both brushing and padding on should work perfectly well. I am currently restoring an antique cedar box that was painted, stripped and then re-coated with a shellac finish (but it was done very poorly) by the previous owner. In tidying up this box, I have had to re-paint strip sections, thereafter clean it off (neutralise) the paint stripper, thereafter sand (medium and fine grade papers) and from there first off I have coated with shellac by paint brush and from there by padding. The one difference between brushing and padding, is that brushing will result in thicker coats (this can in theory cause some problems including shellac rings etc as it drys), whereas padding is excellent for flat surfaces and will give a thinner coat, which therefore takes multiple coats to build it up. The other thing is the density of the shellac mix, as this too can cause problems. Too thick will make it hard to work with, too thin will take too long to get a satisfactory finish.

You do need from my experience to cut back every 3-4 coats to get a really sound coating (depth of finish). True French Polish yet again takes this polishing to another level.

Problems in terms of finishing with shellac (over old coatings) is that it can cause bubbling of the old shellac, it can loosen off and result in an uneven finish which is unsightly (hence) if the shellac finish is tired in my view you are always best off stripping it off. The alternative if not too far gone would be to use a finish reviver (Ubeaut can provide this).

Temperatures, (hot or cold can also affect the polishing process). If too cold, then the shellac finish will go white/and is extremely hard to work with. If the temps are too hot and/or it is humid this equally can cause issues, including it drying too fast or becoming sticky. One trick French Polishers use is to put a drop of a mineral oil or similar on the shellac pad to help keep the surface workable. The other thing is, I don't think you really need to get the pad wet with metho first before using shellac. If padding the core should be wetted with shellac and the outer layer over this just needs to allow the shellac to soak through it, thereafter apply a few drops of oil onto it and it should pad smoothly.

The other thing I don't think the cloth you are using should be a problem (but only use lint free cloth). The only other thing is the padding strokes. Normally French Polishers apply in both a circular or figure of 8 motion, followed by parallel strokes following the grain of the timber.

Goodluck with the project and I do hope you can get the shellac to work for you.

[MrTwistie]

It's a bit late, however I'll add my 2bob.

i believe you need metho that is at least 90% spirits, preferably 99%. 50% is too low, the other 50% is likely water..

I would also recommend cheese cloth to wipe on, it's a nice and smooth material and holds the shellac better.

[shanesmith80]

[QUOTE=
like Neil shows at the end of the 4th video he posted [/QUOTE]

What videos? Where can I find them?

[jimbur]

I saw a video with Frank Klausz in which he used a padding lacquer instead of traditional French polish. It was applied by rubber in exactly the same way but is much more forgiving than shellac. I tried it (Qualasole was the brand I used) and was quite impressed. However, it does not fill the grain like shellac so you have to start with an absolutely flat, well-finished surface. It's an easy way to get into French polishing. On the plus side it is more robust in terms of alcohol and heat. I still prefer shellac french polish but then that is what I was brought up with.