Varnishing / lacquering is one of the oldest woodworking finishes available and can be applied to raw MDF as well as to a veneered finish.
Varnishing / lacquering is one of the oldest woodworking finishes available and can be applied to raw MDF as well as to afinish (we use the terms varnish in this document to include lacquer even though they are quite different materials). We recommend that you varnish or oil all finished real wood veneered kits for long life and to ensure adequate UV and surface protection. The finish you will achieve with a varnish depends, as with painting, on the preparation. Having said this, varnish over raw MDF is a little easier to apply than a paint and is much quicker.
For best results, we recommend only applying varnish with a spray applicator or a spray can. It is very difficult to achieve a satisfactory result using brushes, although with care it can be done. You should also follow all instructions provided with the varnish you purchase.
The range of varnishes available is almost as wide as paints, and each type will give a different result. Clear coat spray cans can be purchased from as little as $3.99 and these give a quite adequate result. Note that these may not be called varnish or lacquer but although the chemistry is different, the end result will be similar.
Some of the huge range of common varnishes, oils and stains suitable for our kits.
Choose a varnish that suits the look you want, either gloss or satin and with or without a stain in it. Note that applying a stain to raw MDF is a difficult process and it is very difficult to achieve a uniform result. Staining the real wood veneers, on the other hand, is easily done and produces an excellent result. Your local hardware or paint store should carry a range of varnishes and lacquers and can advise on the best one for your application. A very popular finish for raw MDF seems to be the all in one cans such as Wattyl's Estapol Satin since this gives a clean fresh finish, is simple to apply and the finished look matches most modern decor (see below).
Preparation is the single most important step in the varnishing process. If you want to achieve a superior result you need to plan this prior to assembling the cabinet. The use of multiple wood clamps to minimise any gaps on the seams of the panels is highly recommended. We do not usually recommend filling the seams as we do with painting since these gaps will not be especially noticeable through the varnish but the wood putty will be.
Sand with 240 or 320 grit paper and ensure there are no high spots or ridges showing. If you are using a gloss finish then you may wish to sand again with progressively finer grades of sandpapers to achieve a mirror type finish.
To varnish over a cabinet that has been veneered already you need to lightly sand with a 240/320 grit paper and then remove all traces of dust from the box. Be careful not to apply too much pressure when sanding as the veneer is quite thin and can be easily damaged by over enthusiastic sanding.
Using a tack-cloth (or a clean lint free rag) carefully remove all traces of dust from the cabinet, but do NOT use a "prep wash" or "wax and grease remover" solution as this will damage the MDF.
Place the cabinet onto a raised surface for spraying so as to avoid splashback when spraying the bottom edges, some small wooden blocks or even the lids from the spray cans do this job well.
MDF is very absorbent when painting or varnishing and as we are not using a primer coat with varnish it will require multiple coats to achieve a uniform look. The first coat should largely be absorbed by the MDF and will give a very uneven look to the MDF. Make this first coat very light and resist the temptation to apply more varnish as this will cause runs and ruin the result. It is normal for the end grain of MDF to be much darker than the side grain and so the seams in the box will be quite visible, and in fact become part of the attraction of the finish. If you are varnishing veneer then often 1 coat is sufficient.
Carefully spray the first of the top coats onto the box, working from the top down. Use multiple light coats rather than one heavy coat for best results. The number of coats you apply will also affect the appearance, spray only 2-3 light coats for a plain "natural" look as shown in the photo above or increase the number of coats to darken the finish to a honey colour, as shown below.
To spray all 6 sides at once, you can suspend the box from a bracket made from stiff wire such as a coat hanger. Place this through the cutouts in the front of the kit so that it does not contact the outside of the cabinet at all. Alternatively, you can simply spray 5 sides and then, once dried, mask them off and spray the remaining panel.
Allow the varnish to thoroughly dry before fitting the speaker drivers. Many of the solvents used in varnish are harmful to the glues used in driver voice coils so we recommend you leave the cabinets in a well ventilated place to air out for at least 24 hours before final assembly.
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