Sanding between coats of shellac

[barri]

I googled this and got so many different opinions. Some say sand after the first coat but not the next three, some say don't sand until the 4th or 5th coat, some say not at all until the rub down phase, some say between every coat. Most agree, however, on 220 or 320 grit if you do have to sand. I guess this is like a cooking recipe, everybody does it differently. I experimented with 7 light coats and no sanding. Rubbed out with 0000 steel wool and wax. Looked great. I tried sanding between every second coat and then rubbed out. Also looked good but was a little smoother on the touch. I've come to the conclusion that sanding between coats of shellac makes little difference provided you rub out with 0000 steel wool and polish with wax or burnishing cream or even automotive products. I've tried the zinsser spray shellac, dewaxed, and also buying the feast weston flakes and making my own with metho. Not sure if this is dewaxed or not.

Anyway what do others do? How many coats? Sand between coats? Rub out? Clear or amber?

I'd like to hear what your favorite recipe is for finishing with shellac

[Xanthorrhoeas]

Hi Barri,

As you say, everyone will have their own technique, just as everyone has their favourite shellac type. It really depends on what you are polishing and why. Different timbers respond differently to being polished and you sometimes need a super-smooth finish and sometimes not. The more often that you rub back the smoother, higher sheen finish that you achieve. I only ever use the 0000 steel wool after a final finish. Small fragments can break off the steel and then can rust with time giving ugly brown spots in your finish. I use a range of wet and dry papers to rub back between coats. Nothing coarser than 400 grit and, for final layers usually 1000 to 1200 grit. Others decry such fine grits because they clog easily - but they suit what I do. (Of course I start off with using much coarser grits and gradually get finer as I finish the timber for new items, and I usually go much finer - to about 600 grit - than others here too, which is not generally recommended - but it works for me).

It also depends on how the shellac is applied. If you want the most transparent, lustrous finish the shellac needs to be well diluted and needs to be applied with a good French polishing rubber. Then sanding back with grit wet and dry between every two coats keeps the layers fine and gives the smoothest finish. If you are applying more concentrated shellac with a brush - even a really good squirrel or badger hair Leonhardy (or similar) brush then you will not achieve the most lustrous transparent finish and you also need to rub back more and with coarser grits (400 in my case).

When I am restoring an antique I only ever re-polish if the original finish has been removed before I get the piece, or is so damaged that an attempted patch-up fails. So, when I do re-polish an antique I am attempting to create a finish that looks aged and appropriate for the piece and I vary my technique to suit. For example, most (probably all) pre-1850's Australian cedar furniture was not grain-filled prior to polishing so it still has open pores, often partly filled with wax. In that case I use a raw shellac (brown button shellac) that I crush and make into solution myself. It is very waxy, which is good for the compatibility with the black wax final finish. For such a finish I only rub back (with 1000 grit wet and dry) after I have bodied in and then every five coats or so. It depends on how smooth the finish stays (if the grain raises etc.)

However, if I am polishing a new Huon Pine, Blackwood or Musk piece those timbers have no or far fewer open pores and readily take a finer finish. For a jewellery box I probably rub back every couple of coats. Then again, my wife prefers a satin finish so for her I rub back less and apply fewer coats.

Speciality shellacs like hard shellac and dewaxed shellac all respond differently. I use hard shellac on items like coasters that will have hot cups on them or tea caddies that will be near boiling kettles. I find it gives a good medium sheen finish (not super-high polish) with either no rubbing back or perhaps just a little depending on how the timber responds.

The great thing about shellac is that it is so easy to reverse with metho if you aren't happy with the result, then you can try again.

[barri]

I think what you mean by hard shellac is what Americans call a "pound cut". This in itself is another variable to take into account. A one pound cut is one pound of flakes to one gallon of metho or in our language 1gm to 8mls. A two pound cut is 2lbs to 1 gallon etc. A 2lb heavier cut rubs out beautifully after waxing. A 1lb cut gives a thinner layer allowing you to add more layers. No wonder people get confused with this. The bottom line is, I have never had a poor finish using shellac, its just the degree of sheen and smoothness.

Xanthorrhoeas, when you say use wet and dry between coats what lubricant, if any, do you use?

[Yanis]

I think it is good to keep in mind that shellac does not change its chemical composition on drying. Most finishes actually change chemically and "sets" typically by forming cross linked chains which is irreversible. Shellac however simply dries and can be re-activated with alcohol (meths). Keeping this in mind helps to understand its application.

However if the shellac is mixed then the other chemicals may change on drying so this will change how it is applied and its re-activation properties.

John

[Simon.T]

I think what you mean by hard shellac is what Americans call a "pound cut"

Hard shellac is this stuff from our forum overlords: HARD SHELLAC - New improved formula finish. (http://www.ubeaut.com.au/hardshell.htm)

[Yanis]

Hard shellac is this stuff from our forum overlords: HARD SHELLAC - New improved formula finish. (http://www.ubeaut.com.au/hardshell.htm)

Which means of course that it cannot be re-activated. Swings and roundabouts.

"After shellac has been dissolved in ethanol* it is possible to introduce additives that cause the shellac to cross link after it has dried. This cross linking takes about 20 days to completely cure, less in hot weather."

This should fix the age old "white ring" issue too.

John

[barri]

Using the spray shellac is an easy but not an efficient way to go. I'm interested in the stuff that Masters sell. https://www.masters.com.au/product/900022876/zinsser-bulls-eye-shellac-traditional-finish-sealer-clear-3-78l

Can anyway tell me if this is waxed or dewaxed and what pound cut it is?

[Christos]

in regards to your original question I don't sand the first coat of shellac. I normally use a brush and very light application of the brush stroke.

Sorry I am not able to comment on the shellac from Masters.

[stewart59]

Did you find the Zinsser spray shellac worked well? If so, where did you buy it?
Thanks

[barri]

Works very well. About 7 light coats looks great.

Got in on line at .....

https://www.paintaccess.com.au/collections/zinsser-products/products/zinsser-bulls-eye-clear-shellac-spray-340g


(https://www.paintaccess.com.au/collections/zinsser-products/products/zinsser-bulls-eye-clear-shellac-spray-340g)

[stewart59]

Thanks. I also found it at Crescent Hardware at Annandale. Still practising to get an even coat.