Bespoke musical instruments from the North West of England

French Polishing in practice

The articles by Milburn are a really good introduction and I can recommend the book by Philippa Barstow and Alan Waterhouse, for the definitive instruction course.

The man who taught me, was luthier Tony Johnson. So from personal experience I suggest the following-

Make sure the instrument has as perfect a sanded or scraped finish as possible. All imperfections should be dealt with before you start to apply the French polish. This finish will highlight any scratches or dings, it does not hide them, so be warned.

You need a good sable hair brush about 1 to 2cms wide that will form a knife point edge when wetted with polish, and a rubber made from 6 inch squares of well worn T shirt material or cotton bedding sheets. The filler for the centre of the rubber can be cotton wool or similar. A fresh bottle of Special Pale Polish (SPB), as small a volume as you can buy. A little goes a long way and a 500ml bottle will easily do two or three guitars. Once the French polish is made, by dissolving the dried resin in alcohol, it has a shelf life of about 6 to 9 months. But in the dried form the resin will last for years.

Cup one or two sheets of material in your hand and place a small, golf ball sized piece of cotton wool in the centre. Pour on enough SPB to wet the cotton wool. Fold up the corners of the cloth and bring together then twist and form the round rubber. For edges and corners a more pointed rubber is needed and this is formed by folding over and over the edges of the cloth and with none or very little cotton wool padding.

You are now ready to try this out on a scrap piece of timber. If you like Chinese meals and have an empty soy sauce container then these prove to be great dropping bottles for the SPB. Otherwise place the pad of the rubber over the open neck of the polish bottle and tip gently to wet the outer surface of the rubber. Press flat the face of the rubber with your fingers and it should feel damp but not wet. Reapply polish until this damp feeling is achieved. You can now start to apply the polish onto the wood; using a random circular motion. Eventually you will cover all the wood surface with these random movements. Do not stop the circular motion with the pad in contact with the wood. This will leave  a thicker deposit of polish where you stopped and lead to an unevenness of the finish in the later stages. There should be some resistance to the motion but not a great deal. If in doubt add more polish to the rubber and try again. The first few coats readily soak into the bare timber and dry quickly. All the more reason to keep the circular motion going and do not stop. Allow 10 to 15 minutes between coats. A coat is when you have covered all the surface. It's easy to tell where you have applied the polish on the first few coats but it  progressively more difficult as the finish thickens and starts to leave a shine. Do not apply more than three coats in any one day. Again the drying time will depend upon the amount of polish applied and the room temperature. The drying is just the evaporation of ethanol from the layers of polish. After four or five coats, the finish can be knocked back with a fine, at least 320grit, wet and dry paper, used dry. This will matt the finish and allow you to see where the next coats are applied or not as is the case. Be careful sanding near the edges of your work piece as it is very easy to cut right through the polish back to the bare wood. You should be able to tell at this stage which areas your technique is missing or leaving very thin layers. So amend your random circles to compensate.

Easy isn't it, on flat pieces of timber. But now the tricky bits, the edges and the corners.

Edges can be missed or worse, over applied and polish runs down the side, leaving a raised lump. Take care with this, wipe away drips and runes as soon as possible. But failing this the problem can be rectified by more elbow grease or in bad cases sanding off the offending area and starting again.

The second case, i.e. corners is where the sable brush comes in. Dip the brush in the polish, dry off any excess and then with care introduce the knife edge of the brush into the corner. Then with a swift, light stroke, pull away from the corner to feather off to nothing across the flat area of the workpiece. Repeat this action along all of the corner to be coated; on both faces of the corner. Then make a smaller rubber this time pointed and use this to blend the brushed area with the main flat area where the large round rubber has been used.

The polish is very thin and watery so take great care not to apply too much polish with the brush, or you will get runs which will give dry to an uneven finish.

So in general any flat areas can be treated with rubbers. Any corners can be fill by brush and then by small pointed rubbers. Curved areas such as the back of the neck or a slotted head stock are better coated using just a brush.

Apply little and often, allowing more drying time with each subsequent coat. When a few layers have been built up you can then make the application easier by lubricating the rubbers with a drop of oil, vegetable or mineral. I use "3in1" and it works fine. Some use only the finest virgin olive oil, I suppose it smells nicer. Here the oil forms a lubricating layer between the polish already applied and the polish in the rubber. When you apply the polish it should be seen to flash off from the swirls, indicating that you are doing it correctly.

Here is where lots of elbow grease is required to go over and over the finish until you are satisfied. This bodying up stage continues until you have filled all the grain or are too tired to continue.

The finish will appear quite dry but it takes several weeks to gain full hardness. Even then this finish is not robust, but it is easily repairable.

You can at this stage Spirit off the finish to give a smoother shinier surface. Here you make a new rubber with just alcohol or methylated spirits, plus a drop of oil. Take care if you do this as you can apply too much alcohol which will soften the existing French Polish.

I found I did not need this stage as I went on to use micromesh and T-cut  as follows-

What finish do you want, matt, gloss, high gloss or mirror? For matt knock it back with coarser grades of micromesh. But if you want a mirror finish then use sparing amounts of T-Cut to bring up that shine. Be careful though, if you have not filled all the grain with polish then the T-Cut will fill the crevices and dry out white!!! Not good on your Indian Rosewood back and sides. This latter stage also takes an inordinately long time and lots of elbow grease.

So there you have it a short potted history of how I did it and look in the Gallery for the bowl backed octave mandolin to see the results. Note the fingerboard was left bare wood and the soundboard was just an oil finish, it was the rest that was French polished.

Points to be aware of-

1. you may need to slightly dampen the timber to raise any grain, the first coat of French polish may do this for you. But remember to sand smooth before applying any further coats.
2. certain woods can leak pigment, so take care, do the sound board first with a fresh clean rubber. Purfling, binding and inlay materials may also be a problem. Use a brush application for the first two coats. Once sealed there is much less chance of bleeding of from one timber to another.
3. you can add colour to French polish. Use artists pigments, see Cornelisson in the suppliers index. For most uses, especially repair work, a combination of Prussian Blue, Indian Yellow and Alizarin Crimson will suffice. Note these pigments in French polish do not produce opaque colours; but subtle translucent shades.