Speaker Repairs Part 1: Sanding veneer

Old speaker cabinets are frequently covered with Walnut veneer. This creates some limits to what can be restored, as the veneer measures usually only a few mm. If your speaker cabinet is built from real wood, you can sand the cabinet until stains or scratches are gone, which might destroy a veneer cover.
Our test speaker, a pair of Ohm C2 speakers, has cabinets made from plywood at the sides, bottom and top, all covered with walnut veneer. The front of the cabinet is real walnut. If you like to see more pictures about the original condition of the speaker, have a look here: C2 Ohm Speaker

Cabinet veneer before sanding

The veneer of the cabinets has threemajor problems. In the left picture it shows the extent of dust and dirt that has been accumulated on the top of the cabinet. After many years this dirt is sticking on the veneer and became very persistant. The middle picture shows the bottom of one of the cabinets. Many scratches and stains are on it, probably from pushing the speaker over the floor at some point in time. The third picture shows the side of one cabinet. White paint is all over the side of the cabinet and sticks deep in the rills of the veneer.

1. Cleaning
It is crucial that the speaker cabinets are completely clean, before you use any varnishes or coatings. To clean the speakers we used some soft brushes to get rid of the all the nonpersistant dust and dirt. Don´t start cleaning dirty speakers by wiping off dust or dirt with towel, as you might scratch the veneer! After removing the first layers of dirt and dust, a wet towel can be used to carefully wipe the veneer clean.
The color at the sides of one of the cabinets turned out to be not water-based. This can be a problem, as chemical cleaners can be aggressive to veneer. We recommend to use a wood cleaner, such as the one on the right (click it). Also, as many cleaners are potentially agressive to the old veneer, we recommend to dilute cleaners with water.

2. Sanding
After the veneer is cleaned, use a 200 grit then a 400/600 grit sandpaper to sand it carefully down. Be aware that veneer is a very thin slice of real wood, not fake wood. On the one hand you can work with it like real wood, on the other hand you need to be careful to sand only a very thin layer of the veneer. After each sanding, wipe the veneer off.

3. Results
After cleaning and sanding the Ohm C2 speaker cabinets, the veneer looks already much better than before. The cleaner (we used a cleaner for latex paint) was able to remove most of the paint. Ideally, the surface of the cabinets should now be nearly evenly colored, indicating even sanding. However, after applying oil or other finishes on the cabinet, you will hardly see small differences. For our little project it is sufficient to remove the white paint and sand the worst spots. Being careful with the alredy damaged veneer, we rather avoided too much sanding. The sanding process helped to flatten or remove many of the scratches and pepared the cabinets for the next step: Now it is the right time to protect the wood from future damages. Check out part 2 to read about appliance of oils and danishes

LEFT: Nearly all paint has been removed.                                        RIGHT: Condition of the veneer after sanding

 Some more sanding tips for veneer Link to forum discussion about sanding veneer