French polish, the classic method of applying shellac

I promised you when I wrote about shellacthat I'll pick up the subject to say more about French polish - special method of applying this natural varnish. I don't forget the promise, so here follows a series of details and tips that are sure to make you want to varnish at least one small wood using this method. At least that was the reaction with me.

The shellac application process is a time-consuming, repetitive, labor-intensive process. Application techniques are very much up to the individual specialist, with experience gained over time helping them to find the method that best suits the way they work. Whichever technique is used, there are some common elements: preparation of the varnish, the substrate, the pad to be applied and the mandatory principles during application.

The first operation is obtaining the lake flakes. As you've seen, shellac is mostly sold in solid form because it doesn't last very long ready-mixed. It is also available, but it contains a number of additives that prolong its life and can affect the final quality. It is therefore best that the lacquer is prepared by the person applying it. Shellac flakes or shellac buttons are dissolved in denatured spirit (industrial alcohol). There are several proportions in which dilution can be done, but the most commonly used are:

• 350-360 g/l of alcohol - for primer or primer coat applications or for painting applications for substrate preparation. In this case use only dewaxed shellac;
• 240-250 g/l of alcohol - the most commonly used proportion for application and sanding;
• 100-120 g/l of alcohol - the final coats which are applied without intermediate sanding and which give the mirror gloss.

Choose the flakes according to the desired color and grind them very finely in a grinder to dissolve them more easily.

It is best to use glass containers with lids so that you can stir the mixture. Do not use metal containers as they interact with the components. After weighing, measuring and mixing, put the lid on, shake the mixture well and leave for 1-2 days for complete dissolution. Finally filter through a fine cheesecloth to remove impurities. If it's a cold spell, for faster dissolution, you can put the varnish bowl in a bowl of warm water. Be careful, do not put the pot directly on the fire or in boiling water because the high temperature spoils the varnish.

The next step is buffer preparation with which the application is made, shfam as they call it experts. It can be made from cotton wool, pieces of old knitted or woollen bumbarc, which are placed in a piece of finet or cotton, tightly pressed and knotted so as not to come undone during application. Finally, the pad is tapped a few times against a flat surface to weave and settle. The underside should be well stretched and flat, with no wrinkles, seams or holes, which may cause the varnish to be applied unevenly.

Before applying the varnish the wood surface must be prepared and sanded very well. Repair scratches and holes. If the finish is to be satin-finished, sand large-pored hardwood (walnut, oak) with 400-grit sandpaper and finer-pored hardwood (walnut, oak) with 600-grit sandpaper. For mirror polish, use 600 and 800 grit paper respectively. Musical instruments are sanded with 1000.

Loading the tampon with varnish is done with great care and by pouring in the milk a little at a time. It is best to use a pipette. The pad should not be mushy, but it should not be dry either. You can test it on the back of the palm of your hand, where it should feel moist and the milk should not run. Finally put a few drops of mineral oilwalnut or olive oil. Linseed oil is not good because it is too viscous. The oil helps the pad to glide, and the varnish doesn't get trapped on the wood in large quantities. Loading the pad is where experience speaks for itself. You will only know the right amount of varnish or oil once you start working. If the pad sticks to the surface, too much varnish or too little oil has been applied.

With everything ready you can get started actual application of the varnishwith continuous circular or figure-8 movements. Never stop because a dent will appear. Even if the pad is dripping varnish, the movement must not stop. Continue moving towards the edge. Stopping should not be done abruptly but as a continuation of the movement. From the rotation of the hand, you practically come out to the edge of the piece.

Shellac dries quickly compared to other varnishes or oil, in 5-10 min. After each application the surface is sanded to remove any unevenness. Even if it dries in 5 min it is better to sand after 20-30 min. First sand with 800 grit, then continue with 1000, 1200 or fine steel wool. Even 30 coats or more are needed to get a nice surface. For mirror gloss, use thinner varnish for the last coats and do not sand between coats.

Applying shellac is no simple matter, and it's a good idea to call in specialized firms if the project involves old pieces of furniture that need to come out perfectly. Just like the article on recovering 100-year-old furniture.