Restoration 2
Here is information about the restoration of polyester lacquered surfaces:
This article deals with the restoration of radios with damaged polyester polished surfaces that were made available from 1959. Up until 1959 the surfaces of our radio cabinets were sprayed with nitrocellulose lacquer. With this type of lacquer one must allow at least 24 hours drying time to prevent damage to the pores. To correct this inconvenience on the operation one tried to improve the spraying process with the help of dry chambers or dry cabinets. However the results demanded today are no longer satisfactory with this process. (that was 1959) There fore for some years now Polyester lacquer has been recommended as an improved surface product. Its advantages over nitrocellulose lacquer are as follows:A glass clear gloss to the surface which is resistant to scratches diluted acids and alcohol based liquids. Also the process is easier because of the better drying time of the polyester. With the introduction of polyester some reeducation of the workers as well as some modification to the equipment used was necessary. Everything from the spraying to the final polishing had to be unlearned and it took time for the workers to become familiar with the product. Also there was an increased number of products with polyester surfaces on the market. They had to be so confident with the product that even small amounts of damage in transport and when in situ could be avoided.
Enough of the preamble - now to work! Light scratches can be treated with 600 grade sandpaper and afterwards buffed with a small buffing machine first with a greasy buffing paste and then with a dry buffing compound. Rougher damage is somewhat harder to eliminate but basically all damage to cabinets can be treated. To explain better we have the following examples which show each stage in the operation to restore from a serious case of damage.
Picture 1
A cabinet had fallen on an edge and the coat of varnish was badly damaged. With a sharp knife the varnish coat is removed. The size of the damaged area is highlighted in the picture.
Picture 2
Here is shown the edge on the area and its surrounding area being treated with 500 grade sandpaper. This must be done very carefully to remove all greasy traces of the polish since good adhesion of the new lacquer will only be possible on clean surfaces.
Picture 3
When sanding the timber it will be seen that bright tones in the wood will be revealed. These can be treated with Indian ink or stain. As every woodworker knows pretend grain can be achieved with stain or ink. A most beautiful simulated grain can be achieved with ink and brush.
Picture 4
after the retouched area has dried, as moisture is unfavorable to good adhesion of the lacquer, a little of the lacquer is mixed up. Ten parts lacquer to 1 part hardener is mixed. if possible use porcelain or plastic containers to do the mixing. Mix quickly because after fifteen minutes it begins to harden. The experts say that it has a useable time of 15 minutes. As seen in picture 4 the lacquer is applied liberally with a brush. Apply with the surface horizontal so that the lacquer goes on well. Wash brushes and containers immediately after use with suitable solvent or else they will jot be useable again.
Picture 5
After about 4 hours the applied lacquer will have hardened and can be worked on further. With a scraper, not too big, as seen in the picture any excess lacquer can be removed from the damaged area which is now sanded smooth. An even scraping motion is required in order to avoid damage to the surrounding areas. Please follow the picture exactly - the person scrapes from the large area outwards. He also uses the index finger as support so that the scraper does not redamage or scratch the surface.
Picture 6
Shows further work on the damaged area. It shows further sanding of the area. it is with 400 grade sandpaper and sanding block. Some practice and caution is necessary here to erase all imperfections in the lacquer. In the picture you can still clearly see the seam in the adjoining lacquered area. In the lower left edge the seam is no longer visible. .
Picture 7
As in picture 6 when the lacquer seam is gone we go on to the last step in the process. This is the buffing. For this purpose in 1959 the Lowe Opta factory used a buffing machine type Flex DL 14 made by the company Ackermann and Schmidt of Stuttgart with the appropriate buffing wheel. The buffing wheel is coated with buffing compound and held against the surface. The lower edge of the disk will moisten itself by friction as shown in the picture. Plenty of pressure is needed here: the surface can easily warm up. After a short time the damaged area will be completely restored. The buffing wax is cleaned and degreased with one of the polishing agents available today and the set is as good as new.
I hope that you like this article from 1959 from the Loewe Opta Courier written by A. Franz and helps you restore damaged cabinets or even other things finished with Polyester lacquer. This method is after all still applicable today.
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Hans Stellmacher September 2001