Repairing the Lacquer of a Qin (琴漆修補記)

By Charles Tsua 14^th August, 2006, updated 3 November, 2008

Preface

About a year or two ago, I discovered a dent on the surface of my qin located on the path of the fifth string at the 11^th hui. I ignored it at first, but it later became deeper and began to hinder play; when I played the 10.8 position on the fifth string, my fingernail would dig into the dent. So, I needed to mend it before it got any worse. I also wanted to mend the crack that developed at the back of my qin; a crack formed due to climate change on a natural fault in the wood that ran from top to the bottom of my qin. The crack was not too wide or long. After a few months of trial and error, I more or less have finished learning what there is to know about the process of repairing the lacquer.

On the internet, I haven’t found an account which fully discusses the process of repairing lacquer cracks in detail; about the exact amount of each ingredient to use, the drying times, etc. So here, I will write down my experiments and findings of my experience in using lacquer and hopefully, it would be of use to those who wish to make their own repairs. Since we do not have access to qin makers here in the west, it would be appropriate for players to do at least minor repairs. Of course, we cannot deal with structural problems.

After more discoveries regarding the whole process of repairing lacquer on the qin from Professor Zeng Chengwei, I have now made additions and corrections to this paper. Corrections and deletions will be highlighted.

Abstract

We shall discuss the following:

Obtaining the appropriate materials — Assessing what repairs need to be done — Preparing the qin — Preparing the lacquer mixture — Applying the lacquer — Polishing — Notes on lacquer

Obtaining the appropriate materials

It is necessary to obtain the appropriate materials and ingredients for the repairs, otherwise, the result would not be good. The first important ingredient we must obtain is lacquer. There are two types, natural lacquer 天然漆 and cashew lacquer カシュー漆. We can use either for minor repairs. However, natural lacquer is toxic and can give some people allergic reactions, plus it cures very slowly. Cashew artificial lacquer is not toxic and dries fast, but according to some accounts, doesn’t last as long as natural lacquer, and is its fumes are a potential health hazard, so a mask is required. (I owe this point to Jim Binkley.) So, which lacquer to use? One should always aim for the best, and if they cannot obtain the best, then we can use the alternative. We will discuss the use of natural lacquer here.

We can obtain lacquer from various on-line merchants, particularly Japanese sword repair shops, which sell small amounts of lacquer. Note that the name for lacquer in Japanese is “urushi” うるし. Some merchants give you a choice of lacquer: raw, black, clear, coloured and gloss or matt type. I personally have used a clear gloss type which works. It gives a glossy finish, though this may not be desirable. Apparently, the ‘raw lacquer’ sold is not really ‘raw’ but already processed. The clear and other varieties may have undergone additional processing. I have yet to see if this is the case.

The next important ingredient is deer horn powder 鹿角霜. This is easier to obtain. From the Japanese stores, it is called tsunoko 角粉 powder and can be purchased in large amounts. Deer horn powder is necessary for the base repairs. The powder should be very fine and white, like flour, meaning it has gone past the ‘flying-white’ stage. One could of course get a piece of deer antler and pound the powder oneself but this is really much more suited for putting the base coat on a qin in the making than for repairs as it would be too coarse.

Other minor items we need are turpentine 松節油 or similar solvent and application tools, like brushes and containers. It would be best to use a good quality turpentine, like those used for oil paintings. Normal turps can be used to wash brushes etc. You also need a large, flat palette knife with a straight edge.

For polishing, we need a fairly smooth stone for base lacquer and an ultra fine sandpaper for the finishing off (in particular, a P2500 grit sandpaper would be appropriate for an exceptional finish).

Assessing what repairs are needed to be done

The next stage is to assess the symptoms of damage on the qin. Structural damage, such as joints splitting, large cracks, etc cannot be repaired by oneself and needs expert attention.

Cracks less than half a millimetre wide can be repaired easily. Dents can be also mended, but deeper or wider dents can be difficult. Damage caused by wear and tear, such as xingyun wen 行雲紋 or “running-cloud markings” (caused by continuous sliding on the strings, rubbing the lacquer until it becomes thinner) can be repaired easily enough. You can spot these markings as they are lighter in colour and you can feel them as depressions on the surface of the qin. Lacquer that has flaked off due to bumps or small cracks on the joints of the peg protectors can be dealt with.

With cracks, it is best to see whether or not they have stabilised. Sometimes, cracks develop on the natural faults in the wood due to a climate change. One needs to stabilise the crack first to stop it from widening any more before attempting to fill it in, otherwise, the crack will still widen and the repair will have been redundant.

Whether or not one should repair depends on the situation and where the problems are. If there is minor cracking on the back that does not affect sound quality of play, then one need not repair it. If the cracks are on the surface and they impede play, then it would be a good idea. Generally, if one decides to make repairs, it would be best to do all necessary repairs on the qin in one go. If the qin has duanwen markings, it would be wise to repair only the problem parts, and try to avoid the rest.

Preparing the qin

First, we need to note where the repairs are needed. If the repairs are only to the back of the qin, and the strings do not impede the work, then we need not to do much, except make sure the tassels are tied out of the way. If you are making repairs to the surface of the qin, then it may be necessary to remove all the strings, tuning pegs, etc. or they will hinder the work. Once the accessories are removed, the entire lacquered surface will need to be cleaned and free of dust, especially the parts to be lacquered. A damp lint-free cloth should be wiped all over the qin, followed by a paper towel to remove the excess moisture.

If you are repairing an area where the lacquer is flaking off, it would be wise to flake off any loose lacquer in the surrounding area and lacquer those as well in case they flake off at a later date and affect the current repair work.

One would need to also have a clean work surface to work from. A qin table or side table would suffice. Also, newspapers to pad the qin as well as kitchen towels to mop up the mess and water should be at hand.

Preparing the lacquer mixture

Once the qin is ready to be repaired, the appropriate mixture is made. The two mixtures are the deer horn powder mix and the clear lacquer mix. Depending on what stage of the repairs or what kind of repair you are doing, you should make either one accordingly. Deer horn mix would be appropriate for a base coat; that is where wood is exposed, be it in cracks or dents that require filling in. The clear mix is the overcoat, for wear that is not as apparent as cracks, and for finishing off. The ingredients used and the amounts are important to the stability as well as curing time of each mixture.

Deer horn powder mix (large quantity)

This mixture would be used if the whole surface of the qin is severely damaged and requires a major re-lacquer. For dents and cracks, the smaller quantity is better.

Prepare a small bowl or dish and wash it clean. Then, add the deer horn powder to the dish. Add a small amount of water and stir it until the powder has more or less dissolved into the water. If you added too much water, you can discard some of it, then add more powder. Keep mixing it until it becomes slightly thick, like a corn-starch mixture, but not too thick. Once that is done, add the lacquer and stir it in until it blends together. The colour should be a very light brown. Stir until it turns thick and holds together like a thick pudding mixture. It should hold together and not run. Then, add a few drops of turpentine and mix in. When it is fully blended, it should be ready for application. When you stop mixing it, after a while, it should slowly darken into dark brown before turning dark grey.

The amount of each ingredient is as follows: 4 parts deer horn powder, 3 parts water, 3 parts lacquer and 1 part turpentine. If the damage is severe, you may wish to increase the quantities of deer horn powder and lacquer.

Deer horn powder mix (small quantity)

For smaller repairs such as dents, you only need a small amount. Use a piece of folded paper. Scoop a small amount of deer horn powder onto the paper and add a few drops of lacquer. Use a palette knife to knead and blend some of the powder into the lacquer. Keep kneading more and more until the mixture is similar to a thick paste. This method was learnt from Professor Zeng.

Clear lacquer mix

Prepare a small container and clean it. Add the lacquer into the container, followed by water. Stir until they bind together. Then add the turpentine and stir. The turpentine should separate the water into small drops. Keep mixing until these water drops are blended in fully. Afterwards, the colour should be a milk chocolate colour and turn dark brown if left alone. The mixture should be slightly thinner than the original lacquer, but not as thin as water. Then, you may adjust by adding a little more water, but not too much.

The amount for each ingredient is as follows: 3 parts lacquer, 2 parts water and 1 part turpentine. It is advised not to use lacquer straight out of the tube on its own without adding water or solvent, as it would be too thick and would take months to cure. You can add more water to the mixture to decrease the curing time.

One should not keep ‘overnight’ lacquer; fresh lacquer is better. Also, pigmentation is best used for full qin re-lacquer. The clear lacquer mix is suitable for use on larger repairs. For dents, etc, lacquer straight from the tube can be used.

Applying the lacquer

Once the lacquer mixture has been prepared, you must use it right away. Otherwise, it will form a hard skin in a matter of minutes. It should be constantly stirred or kneaded to avoid this. The method of application varies depending one the mixture you use and what you are repairing.

Repairing minor cracks

You can repair cracks that are less than half a millimetre wide. Use deer horn powder mixture with a little more powder in the mixture. You should use a small implement (like a flat toothpick) to scoop the lacquer mixture onto the crack, then push the mixture into the crack. Keep applying the mixture onto the crack to make sure you filled in the crack sufficiently. When that is done, you can use a flat-ended palette knife to smooth out the mixture evenly on the surface so that the lumps are gone and the crack is not visible. It is essential that the surface is even.

Repairing major cracks

Major cracks are cracks over a millimetre wide. If the crack is over two to two and a half millimetres wide, then it should be considered in need of expert attention and you should not attempt to repair it. The mixture is the same as that for repairing minor cracks, but you need to add an amount of paulownia sawdust/powder equal to the amount of deer horn powder used. It should be mixed with the overall mixture, then applied to the crack. One must make sure the crack is completely filled by using a flat implement to push the mixture into the crack. The finishing off is the same as minor crack repair.

Repairing a dent

If the dent is small, only one application of deer horn powder mixture (made using the small quantity method) is needed. You can apply it using a palette knife, pushing the mixture into the dent then evening it out so the surface is flat. You do not need to remove the strings in such a case, just part them with your other hand.

Repairing “running-cloud markings” and applying finishing overcoat

To remove the "running-cloud markings", you need to use the clear lacquer mixture. Use a brush, a traditional lacquerer’s brush if possible. If you have a fear of brushes, you can use a terry cloth (as suggested by Jim Binkley). Dip the brush into the lacquer, then apply it to the surface. Brush it on thinly, moving up and down the qin. The aim is to keep brushing until the start and end brush marks are gone. To do this, you must brush lightly at the end of the stroke. The brush should lift off the surface at the end of each stroke.

In my experience, a single layer is sufficient. It is a good idea to lacquer the whole top surface of the qin whilst you’re at it. This is to keep the surface consistent. You do not need to do so for the back of the qin, just on the area of repair.

Polishing

Once the lacquer has cured to a hardened state, we can start to polish it. Depending on what mixture was used, we either use a stone or sandpaper to polish it.

Stone

A stone is not really needed except for a full lacquer repair. However in such a case a course sandpaper would do just a well and much more smoothly.

Sandpaper

The sandpaper should be the finest grain you can procure, namely P2500 grit grain. This will create an exceptionally shiny finish. If you don’t want it to be too shiny, you can go for a less high grain, but it must be at least P1200. I ahve found that P1200 is still not high enough. It creates a matt finish which does not match the shine of a finished qin surface. I have forgotten what Prof Zeng used, but it was similar to my P1200. Maybe he polishes it further using another method. The sandpaper at the local hardware store may not be fine enough for the finishing polish. If in doubt, test it on the back of the qin.

The sandpaper is suitable for the final polishing of the surface board. When we use the paper, we will also use water with it and rub it in a linear fashion like with the stone, or circular for particular bits. Essentially, the finish must be very even and free of any depressions. Every time we make a rub, we use a kitchen towel to wipe off the excess water and lacquer residue off the qin. Particular attention should be paid to the sides of the qin. Do not rub too hard for fear of removing too much of the lacquer.

It is essential to get the evenness with the lacquer repair area with the surrounding area surface lacquer. Lumps and bumps will cause over-sanding of the surrounding area when you try to sand and even out the area of the repair.

After that is done, the sanded parts may be more matt than the surrounding area of lacquer. We must thus ‘bring out the shine’ and polish it with lacquer. Apply lacquer straight out the tube on the area (or use a thinned mixture for large lacquer work) then using a clean disposable cloth, rub the lacquer onto the surface to remove as much of the excess as possible. This process polishes the surface to greater shine after sandpapering. Do not rub too much so all the lacquer is removed. You want a very thin layer to remain that is invisible as it is blended with the surrounding area. After the final polishing, it should be left to dry.

This is the result of my own experimentation, and needs perfecting. I think one could use an oil, such as sesame oil, to make the surface smoother, or a special violin cloth as suggested by John Thompson.

Notes on lacquer

When using lacquer, you must be careful. If you are allergic to it, you must wear protective gloves. If you use Cashew, an organic fumes respirator will be needed. The work area would ideally be a shed or a garage. Lacquer is oil-based and if it gets on your hands or clothes, it will become sticky like oil paint and and won’t come off with water. To wash off lacquer, you must use turpentine. Use it to wash brushes and the container, then use normal soap to wash the turpentine off.

The curing time for lacquer varies. It depends on the water content of the lacquer. If the water content of the lacquer is low, then it will take a very long time to cure; if it is high, it will take a matter of days. After the initial water content of the lacquer has evaporated, the lacquer will begin to slowly polymerise and form a hard surface until it binds together. Even though the lacquer is not sticky any more when touched, it may still be soft and require more time to set. If you scratch it, cured lacquer should not leave a scar or feel limp as if it has not yet fully cured. Deer horn powder mix may dry in days, but requires some time to set and cure. You can test if it is finished by scratching parts of it; it should not flake off, as it will if if it has only dried on the surface but not bonded to the qin. Another good way to tell if the lacquer is fully cured is by smell. Lacquer which has fully cured and dried no longer has an odour.

The lacquer will cure best in a humid climate with a high temperature. The ideal climate for this would be a humidity of around 55-75%, with a temperature of around 22-25°C. If your climate is excessively dry (i.e. below 45% humidity), then it would be a good idea to purchase a humidifier to increase humidity. Too dry a climate will result in the lacquer taking extremely long to cure, if at all. Of course, if the humidity is constantly too high, the lacquer will cure too soon; it will be weak and will cling onto the qin rather than bond with it. A dehumidifier will be needed if that is the case. Also, an excessively high temperature is not good for lacquer or for the glue holding the qin together. This is according to the English climate. The summer I first lacquered my qin was exceptionally hot and dry, and the lacquer did not cure. Also, the excessive dryness caused my qin to make worrying creaking and cracking noises (maybe because I took all the strings off and the tension that caused my qin to be stable was removed). In later years, the climate has been more stable (i.e. wet) and the lacquer tends to cure in two to three days.

During the curing phase, it is best to hang the qin on a wall. It is best to monitor the climate using a barometer, hydrometer or similar device regularly.

Afterword

Making lacquer repairs to a qin is a time-consuming process that requires a lot of waiting. The key to success is experimentation and experience. Every qin player should know how to make minor repairs, including how to string the instrument in the traditional way. But I am not expert on these matters and these musings are gathered from my short attempts at repairing the lacquer on my qin, which wasn’t free from errors and mistakes. These instructions may be unrefined. This is just some knowledge I assembled from my studies about qin, my readings from various sources and qin making and from my own intuition on the subject. I hope it will be of use to those interested in attempting their own repairs.

Since my meetings with Professor Zeng, I have been enlightened by simpler methods of repairing dents. Had I known of these, my repairs to my old Ming Yu qin would have not been so messy. Indeed, the method of using a lesser quantity of lacquer and powder on a piece of paper and applying it with a flat-ended palette knife made for a cleaner, more even finish and was in itself less messy.

It is probably better to practice your repairs on a lesser qin than begin with a very good one. That way, if you make mistakes you won’t cry over it.

Created 14th August 2006

Updated 15th October 2008

Copyright © Charlie Huang/Charles Rupert Tsua 2006, 2008