Nick prefaced his talk by saying that Finishing was a big subject and today he was just covering Finishing for Beginners. A full talk on the subject would take about 3 hours.
There are a few basic premises.
Sharp tools = Less finishing problems. Poor care of the grain shows up when stain or polish is applied. Finishing takes as much time as carving.
There are various ways of smoothing the wood. Whatever method is used, the smoothing should be in the direction of the grain and not across it.
Dremels are quick but not easy to get into difficult corners.
Glass paper or emery paper can be shaped to the curve of the carving. You need to go down the grades from the harshest to the smoothest (that is smoother than toilet paper). Keep the worn out bits as they are soft and flexible and may come in handy one day. Emery paper lasts longer than glass paper
Scotsbrite make industrial abrasive pads that are strong and last a long time see Scotsbrite .
Wire wool is effective but careful cleaning of the wood is needed before oiling or polishing, as any bits of metal left on the wood will rust in time.
Powdered pumice can be applied with a cloth or Polystyrene. It comes in various grades.
Polish or oil
There are lots of different products on the market. Nick has experimented with Danish oil for a long time and knows how to get the best out of it. If members want to use other products, he advised that it is tested on scrap wood before using on a carving.
Before any finish is applied, the work should be washed. This removes the grease that has come from the carvers hands, and raises any fluffy bits of grain that the smoothing has pressed down. Apply danish oil with 2% turps thickly and when dry the fluffy bits will be standing proud of the work and stiff with the oil. They can then be easily sanded off.
The number of coats of danish oil depends on the finish required. Be careful to remove any excess from grooves and hollows with a dry brush.
Colour may be added to the danish by adding small amounts of oil paint. Test on scrap wood to see if the right effect is likely to be achieved.
Finally apply a coat of wax to the work
For Scandinavian style work which is usually painted, test a thin coat to newspaper. If you can still read the print, the thickness of the coat is about right.
For spoons that are going to be actually used with food, leave spoons in boiled whole milk for 2 days. The treatment is not effected by any washing up .
Below is a copy of Nick’s handout
Staining and Finishing Woodcarvings
Most convenient to use Wood Dyes (Rustins, Colron, Liberon). These are stains available in a range of shades which can be blended or thinned with white spirit.
Apply first to raw prepared wood as they will not penetrate a sealing coat. Remember that end grain takes stain much more readily, so use diluted stain or pre-treat end grain areas with thinned sealer to reduce absorption of dye.
If polyurethane varnish or oil is to follow, leave ample time (several days in a warm place) for stain to dry out. Otherwise, carving will remain sticky.
When staining a carving, areas which need to be unstained can be blocked first with cellulose sanding sealer (dries very quickly) and any stain in the wrong place can be wiped off with a rag dampened in white spirit. Alternatively, stain which has bled into the wrong area can be carefully chiselled away to expose unstained wood.
Sometimes, a deep knife cut along a stain boundary will stop the stain bleeding across.
Applying the Finish:
Cellulose Sanding Sealer (CSS) is a useful tool in the carver’s armoury.
As mentioned, it can be used as a stain-resist where differential staining is required.
Where carving problems arise with short grain or soft patches, the application of one or
more coats of CSS, thinned with cellulose thinners to increase penetration, will harden up the wood, making it much easier to carve. Always bear in mind however that wood treated this way will not subsequently take stain like untreated wood! (Superglue an also be used for this this purpose.
A primer coat of thinned CSS (+10%thinners) is a good start before waxing or PU varnish application and will speed up drying of the first coat of PU, especially on stained wood.
Polyurethane clear varnish is a good durable finish but should be thinned down (+10% white spirit) to avoid a treacly appearance. Satin and matt versions are available and often more suitable for carved work.
For exterior work, select a varnish with UV inhibitor and flexible build to minimise cracking (e.g. Rustins Flexterior varnish)
Oil finishes are easy to apply – wipe on, wipe off at increasing intervals, and give an attractive appearance. They often enhance the grain of the wood, so make sure that this will be acceptable in the finished carving.
Acrylic varnishes are increasingly popular for Health and Safety reasons and there are some good weather-resistant types available which are suitable for outdoor carvings.
Acrylic paints can be used, then over-varnished to give improved weather resistance.
French polish is not particularly suitable for carved work and does not seem to be used very often.
Cellulose Sanding Sealer. – Solvent – Cellulose thinners
Polyurethane varnish – Solvent – White Spirit or Turpentine
Shellac (French Polish) – Solvent – Methylated Spirit
Acrylic Varnish (gloss, satin, matt) – Solvent – Water
Oils (Danish, Tung, Linseed, etc – Solvent – White Spirit or Turpentine
Wax Polish can be applied on top of any of the above finishes or used alone.