Renewing Shellac Top

[Doug Hobkirk]

My first post on this forum - Hello all - a "Restoration" forum - great!

I do volunteer refinishing for Household Goods Recycling Ministry near Boston, USA. I refinish pieces that are sold (rather than recycled to clients) to defray the operational costs. This piece is on the borderline - we will sell it if the top refinish is successful. It's a perfect chance for me to do my first shellac refinish - next time I will have a much better idea what I'm doing. I am a novice refinisher - I have usually tackled jobs like this by sanding the top to bare wood, staining, and wiping on a satin poly. That works well as long as the piece isn't an antique or the wood doesn't splotch. But I need to learn other methods and I don't have a mentor.

I assume the finish is shellac because it dissolved using DNA (denatured alcohol) and the wipe off was tan and gummy. I wiped it using DNA and paper towels and then 0000 steel wool soaked w/ DNA. I think I've removed all or most of the original shellac. After doing this, the top still shows scratches, spots where the original dye or stain had lightened, a slightly crinkled surface near the front edge (my post-DNA pictures don't show the crinkle but it's still there slightly), and some white residue in some of the pores.

I plan to stain the light spots and maybe the scratches with a red mahogoney pigment stain. I had thought that after that I would just brush on some shellac, but then the questions start popping up -


Should I sand? 320 using a short-stroke ROS?
Do I need do something about the white residue?
Should I pre-seal (I use a product by Zinzer called SealCoat that's 1# or 2# [I forget which] shellac)?
Is there anything else I should do before I brush on some shellac? (I plan on using a canned shellac from Zinzer, which is a heavier cut than the SealCoat - the Zinzer shellacs are very blonde)

Note: The other areas needing touch-up will be dealt with after I do the top.

The pictures show the original chest and then the top after the DNA & 0000 treatment.

[lpg_falcon]

Doug,
Looks like a nice project.

Shellac,
Well, no need to seal, just put a THIN shellac coat on.
Shellac is often used as a sealer anyhow.


I have a suspicion that the "white" patches are simply Raw timber. (No shellac on it, rubbed through maybe).

Now, as for prep work.
Few of ways to go about it.
1 - Strip of shellac as best you can with DNA so it all looks Raw. (Leaving the scratches in it, some call this character).
2 - Sand back Hard till a level that the scratches disappear.
3 - Sand back lightly and then start applying shellac, put extra coats on Raw timber t try to equalize the color.

For best appearance with shellac, I use a cotton rag to apply it.
Rub it on fairly wet to start with.
As you get more and more coats on, rub it on till it gets almost dry.
This will thicken up the coat and tends to remove any streaks.

Good thing about shellac, if it doesn't go well, simply light sand and apply another coat.

Between coats I give a light sand with OLD worn out sandpaper.
If you use NEW sandpaper between coats you will introduce scratches into the finish.

Experiment on a piece of timber first to get your technique worked out.
You should find that Shellac can be a worthwhile finish to apply.

Here is a link to a project I have done recently.
http://picasaweb.google.com.au/vmuddle/RockingChair?feat=directlink
(http://picasaweb.google.com.au/vmuddle/RockingChair?feat=directlink)
Cheers.

Vern.

[Doug Hobkirk]

...Here is a link to a project I have done recently. http://picasaweb.google.com.au/vmuddle/RockingChair?feat=directlink
...
Vern.
Thanks for the suggestions - I checked out your rocking chair project - I was most impressed by the extension you grafted onto the broken back slat!

Doug

[hap97]

To obtain a true french polish, a polishing rubber is used. I tried to obtain a photo on the Internet, but ended up scanning this page from a text book.
It is attached as a pdf file. It will print out OK, if difficult to read on the screen.
Hilton

[astrid]

the whiter patches are not just raw timber, the timber will have faded where it was no longer covered with shellac,it is possibly water stained as well.
give those areas a wipe with oxalic acid before you refinish or youll have patches under the new finish.

you may aslo be able to steam light scraches out.
just put a damp cloth on the scratch and run a reasonably warm iron over it.
this works if the fibres are dented not broken

[Doug Hobkirk]

the whiter patches are not just raw timber, the timber will have faded where it was no longer covered with shellac,it is possibly water stained as well.
give those areas a wipe with oxalic acid before you refinish or youll have patches under the new finish...
Apply the oxalic acid with a rag to the area or be very focused on only wetting the exact area that is discolored? Leave it on for a few minutes and then wipe off? I've never done this, but I assume that my local hardware store will carry oxalic acid.


...a polishing rubber is used...
Thanks, Hilton - I just made myself two shellac pads last night out of lint free linen tied into a ball around some cotton from a T-shirt. I pre-charged them with denatured alcohol and have them stored in two air-tight containers. But I will confess than I am just planning to pad the shellac, not "French polish" (I think that FP implies more work than simply padding).

Thanks.

[Horsecroft88]

Hi guys while I am over here in Aus rather than the US, the process of stripping and re-finishing a shellaced (french polish) surface is the same. And while based on my 19 years of restoring both antiques and antique wooden joinery in my homes, I would like to de-mystify the process of this if I can. Essentially, the process of french polishing is really simple, and rather only a little time consuming and requires some effort.

Ok, in stripping off old shellac you can do this via two ways, either using a caustic based paint stripper and coarse grade steel wool, or using Methalyted Spirits (DNA ??) and steel wool. Neutralising using either oxalic acid or alternatively as I have always done, using warm water and detergent and coarse grade steel wool. If necessary you can also rub the surface once again with Metho.

Once the surface is clean and dry I always use a coarse grade sandpaper (around 180) grade but never sand too hard since marks, scratches, bumps, burns etc are all considered patina in the antique trade and add value to the piece. Basically you do not want to loose them and so would never recommend trying to steam/ironing them out. If you do this you will loose the history of the piece making it look fresh and new. I then resand using fine grade paper (340), always following the grain, until I am satisfied I have the desired smoothness.

Clean off all dust. Then using a mixture of shellac flakes dissolved in Metho to a consistency a little thicker than say water, I either rub on using a lint free pad in a figure of 8 motion or alternatively brush on. For the first layer I usually would add around 3-4 coats allowing to flash dry off in between each coat. I then cutback using fine grade sandpaper and repeat the french polish process. If I am after a high gloss surface I would normally do this say 3-4 times (and sometimes even diluting the shellac mixture with a little more metho between the coats) with after the final coating, cutting back using the finest grade steel wool and then bees wax polish. This process will give you precisely the correct finish for antiques. Its that easy. Dave

[jerryc]

the method of making a rubber and using it is quite simple. The rubber I use is one that was traditionally used by refinishers. It's one I use myself with great success.

First take a square of lint free cloth about the size of a man's handkerchief., linen or cotton are best.
Then take a ball of unmedicated cotton wool abou the size of a cricket ball.

Place the cotton wool on the cloth and begin folding.

First folds are at the top aiming to create a point.

The fold sides and bottom in.

The pointed front makes control into restricted space much easier.

I use a squeeze bottle to charge the rubber and it should always be charged from the back, Never dip the rubber in shellac, The reason is obvious. Charging from the back acts as a natural filter for the shellac.

Do make suree when using it the rubber base is flat and true, that is it has no wrinkles

I always have three rubbers on hand. One for shellac, the other for straight meth and a third smaller one for fine cover.

As It is easy to store the rubber in airtight jars, they are always on hand when needed.

Hope the explanation and photos will help


jerry

[Doug Hobkirk]

...The pointed front makes control into restricted space much easier.
...it should always be charged from the back, Never dip the rubber in shellac, The reason is obvious. Charging from the back acts as a natural filter for the shellac.
...I always have three rubbers on hand. One for shellac, the other for straight meth and a third smaller one for fine cover.

jerry
Jerry -

Yes, it does help quite a bit. I've been using a cotton T-shirt sleeve in the center - the cotton wool seems like it would be better for the job. But I always have questions!

"Pointed front"? I can see tweaking the ball into a point by the way I hold it, but your ball doesn't look pointed, and wouldn't that get in the way of keeping the ball surface free of wrinkles?

I have been dipping the pad into the shellac mixture - your idea seems better. It should keep the pad from being sopping wet.

What do you mean by a third pad "for the cover"?

Thanks!

[jerryc]

Doug,

Perhaps my explanation was a litle lacking in clarity.

The front is folded over to contain the cotton wool and then the two wings create the point. I thought it was clear in the photos but I can see it is a step i should have described.

The front is pointed by the folds and just holding the balls with the pressure of the hand stops wrinkles. It has another advantage over trying to hold with elastic bands etc, If the reservoir is properly charged then a simple squeeze of grip releases more shellac

Hope it clarifies things a little.

As to the third pad I really meant to say that it is a small version of the main pad for use in restricted areas. Blame late night tiredness for the incomprehensible use of "cover"

Jerry

[jerryc]

Just a point of clarification on shellac finish and french polish. The two are often considered to be the same thing which they are not.

Shellac is just that. It can be brought to a high finish even without sanding. I rarely sand. Careful use with the rubber and thin coats can do wonders. Also I use a meth charged rubber as a last coat to vitually burnish the surface. It takes care and timing but the results are worth it.

French polish uses pumice as a grain filler and also because the pumice in the shellac reflects light.

I attach a photo of a vanity unit I built recently in solid blue gum. I wanted the grain to show so no filler was used. However the finish is "off the rubber", that is no sanding at all and no polish after

Jerry

[Doug Hobkirk]

Thanks, Jerry. I wondered if the points referred to your tying it up. I really like the vanity - both the finish and the way it's suspended above the floor.

[jerryc]

Doug,

The close up of the vanity did not come through for some reason. So hopefully here it is.
As I explained, I rarely sand the finish, it is "off the rubber", that is achieved with the rubber alone and does not need polish or any other treatment.
Shellac is a wondr finish and you should experiment.
For example, Often in the early coats I give a LIGHT sanding, just to remove the raised grain but I do not dust it off. The mixture of fine wood and shellac works into the grain with the next application.
In restoring an old piece and retaining the patina, I first try to reactivate the surface with straight meth. It's hard work, but the patina took years to develop. If that fails, I give a light sand and work the dust back in as I have indicated above. Patina is years of polish and dust driven into the surface and I do my best not to disturb it by being too enthusiastic with abrasives.
It's not possible to give a full treatise on restoring shellac but the guide lines and practice should help you improve your understanding.

Jerry

[Horsecroft88]

Thanks Jerry on the heads up on this matter for I too have learnt something from your advice, and there I have been always trying to keep the surface dust free between the coats to help in achieving a nice smooth final surface.

One thing I will say, and perhaps I too need to experiment a little more, though is that I to date have always finished off a piece I am working on by fine steel wool sanding and then bees wax polishing. I generally use two coats of polish if I am not satisfied by the level of sheen desired. I also like the smell of a decent wax :) Mostly have been using McDonalds antique clear or cedar waxes.

If I am after a duller finish rather than dry steel wool sanding, I use the steel wool with wax and this produces a softer/duller finish rather than full gloss.

I was not aware of the difference between using shellac/metho as opposed to the inclusion of pumice in French polish. Just a couple of questions is there that much of a difference in the final finished surface and secondly, where do you obtain pumice from ?? Dave

[jerryc]

Dave,

The main diffence between the two is that as I explained pumice relects the light better. However this is not apparent until the surface is super smooth. Also french polished surfaces because of the build up suffer damage easier and are more difficult to repair. They also require great attention to detail when preparing as the ultra fine gloss finish magnifies every tiny imperfection.

For those reasons I don't french polish.

I'm sorry I can't help with a pumice supplier as it is years since I have done that kind of work.

Jerry

[Horsecroft88]

Oh well not to worry Jerry and perhaps given that French polish is even more susceptible to damage and difficult to repair I at least should stick to what I know and am confident with. Still good to know about the difference, and if I do come across a supplier of pumice I can always experiment out of interest. Dave

[astrid]

just brush on 3-4 coats of shellac with a very soft brush,
i use a ladies powder brush with gaffa tape wrapped around 1/2 the brush bit to firm it up.
buff between coats with fine steel wool, and run a magnet across the surface to pick up all the steel nibs.

give it a wax and voila
you'll find lots of finishing advice on the finishing forum