I've decided to write up the course notes from the Marquetry course in October. The course was taught by Marc Adams. He covered many aspects of veneering, parquetry, and marquetry. First some definitions: veneer is a thin covering over a core, parquetry is any medium arranged in geometric fashion, marquetry is any medium creating an image. While inlay is a different process, much more difficult as there is access to only one side of the workpiece.
Marquetry was perfected by French craftsmen in the seventeenth century. In this country wood was always cheap and plentiful. Veneer wasn't used until the invention of plywood. This early veneer furniture failed, not because of the veneer, but due to the glue in the underlaying plywood. But veneered furniture took the rap. Veneer has regained popularity over the last twenty years and the best furniture makers now use veneer. Glues have improved and veneer is readily available.
The grain are the rings on the end of a board. The figure is the design produced by the grain on the board's face. Logs are cut into flitches and leaves of veneer are sliced off of the flitch. When shopping for a large quantity of veneer, ask for sequential veneer from the same flitch. All of the wood should match. Each flitch will have the first, middle and last sheets pulled for display. Both faces of the veneer can be glued or displayed. One face does have most of the splits leading to curling when wet. This can be used to bend pieces the correct way for gluing on curved surfaces.
Veneer should be stored flat with a weight on top. Alternatively it can be clamped between boards. It should be kept in the dark. It should be stored in a trash bag with moisture kept at 8-9%. If the veneer is too dry it will shatter when cutting. If it is too wet it will mold and must be pitched. A good place to purchase veneer is Veneer Supplies.
Veneer can be cut with scissors or an eXacto knife. When using the latter a kevlar glove should be worn on the hand holding the work. (A veneer saw can also be used.) Alternatively, a veneer splitter can be used to cut the veneer along marked lines. (This is a chisel-like device.) Small shapes can also be cut with punches. Crafting supply stores have many shapes available for scrapbooking. Veneer Systems has expensive punches for removing and replacing defects.
Veneer can be stacked between sheets of plywood and then cut to minimize splitting, breaking, and tearing. Painters' tape is great for holding pieces in place as they are cut. It is best to get the one hour blue tape as it has the least tack. The tape used for pressing is α-cellulose tape and is activated with water. Just enough water is put on a sponge so it puddles when the sponge is pressed. The ends of veneer sheets should be taped to minimize end grain tearing during use.
For parquetry the best cutting mats are eXacto or Advantage. The Fiskars mat will permanently curl if not stored properly. For parquetry use a straightedge with a sandpaper backing. Ideally something thicker than a ruler should be used. (The straightedges used at MASW were made from Corian.) Wood does not make a good straightedge. Cuts are made against the straightedge. A series of light passes are used to progressively cut through the veneer. Heavy cuts tend to follow the grain and not the straightedge. When cutting cross-grain the edge should be precut to avoid tearout.
To cut diamonds first cut two 1" strips of contrasting veneer. These are taped together long grain to long grain. Cut into pieces with the 30°-60°-90° triangle. A Lois cube is cut at a 60° angle. Six of these can be fashioned into a Jewish star. Alternatively three yield the cube, with unlimited stacking potential. A 30° angle produces long diamonds. These can be assembled into a long border or into a variety of stars. A nautical star uses four long points and four smaller. The template is used to make these points. The template is used to cut the long lines and for drawing the shorter lines, which are cut with a straightedge.
A four-way match with isosceles triangles are the most difficult. The 45° trap should be used. A stop cut should be made. The picture below shows some of the designs that can be made from these few shapes.
Marquetry is cut with conical cutting or the double bevel technique. For this process the table of the scroll saw is tilted with the left side down and the right side up at a 7-8° angle. A #2-0 blade is used. (I found these difficult to locate. I purchased six dozen Pegás blades from Lesley's Patterns.) The blades are installed teeth down as it cutting on the downstroke is critical. If the blade wanders increase the tension.
The double bevel requires that the following rule is strictly followed: whatever is on top is kept and is to the left of the blade. Drilled holes are put in turns or wherever is least obvious. Fingers should be close to the blade. When making sharp turns the workpiece should pivot around the back of the blade. That is, the workpiece should be tight against the back side of the blade through the turn.
When preparing an image for marquetry, the first thing is to trace the image outline. This primary tracing is used with carbon paper to put the designs on the veneer. Before proceeding two things need to be decided. Where is the light coming from and what direction should the grain be going in each part. Then the background and colors of veneer are selected based on the number of different colors needed. Packets are then identified. Packets are entities representing some complete part of the picture with two or more joined pieces. Packets are not just parts of the picture that touch.
A packet is selected. The full entity is drawn on the first piece of veneer (even the hidden parts). The mat is also used for storage of the background and completed packets. The ends of the background should be taped. The second piece of veneer is laid on the first with attention to grain direction. The pieces are taped with blue tape and the second part of the packet is drawn on this new piece of veneer. The junction between the two parts of the packet is cut. The top piece to be kept is always on the left side of the blade. The correct two parts are then separated and taped together. Veneer tape is used for producing packets. Tape the back side. Draw the second piece of the picture on the opposite side. This is repeated for each of the parts of a packet. To summarize the steps of marquetry are listed below.
When cutting thin pieces, the material needs to be supported. This is often done using the tip or back of the eXacto knife, but any thin strong device will work. Veneer tape can also be used on the back side for further support. Veneer tape needs to set for 15-20 minutes first. An alternative is using white glue on the back after it has dried. Finally, the veneer can be conditioned (see below). One should plan the cuts in advance. Cuts along the same line should be minimized.
To put things into the background, the ends of the background veneer should have been taped. Crosshairs should be drawn on the tracing. These crosshairs should then be transferred to the background veneer. The bottom of the tracing and the background should also be labelled. The packet that is the farthest back in the picture should be cut in first. The packet is aligned and blue taped down to the background. A hole should be made with a very sharp point at an intersection, at a point, or hidden if possible. The blade is run through the hole. The packets are on top and stay to the left of the blade. Cut just outside the packet. Tape this packet onto the background with veneer tape. Tape right over the old tape holding the packet together.
When a part of the picture is partially hidden, draw the entire part including the hidden part. Dotted lines can be used for the hidden areas. The entire part is cut into the background. The hidden areas will be taken care of when a higher part in the cascade is cut into the background. Alternatively, parts can be cut in from the back. When this is done the part is taped to the back of the background. The background is now on top so it stays to the left of the blade. Sometimes this is the easiest approach.
For broken pieces save the fragment. It can be taped in place with a drop of glue on the veneer tape. Offcuts of each color of veneer should be saved for later repairs.
The finished product needs to be symmetrical around the core material. A good cheap choice for the back side of the core is a layer of man-made veneer. This veneer can be sized on the guillotine. It is left proud 1/4" all around the core material. This excess is cut off with the knife prior to press gluing the marquetry onto the front face.
One of the parquetry patterns I did not get to is the "fish scale". This template has three curved edges, one convex and two concave. The knife is used to cut around this template. The cuts are made in small sections. The workpiece with templete is rotated, so one is always cutting in the same place. Slowly work your way around the template. The fish scale pattern is challenging to assemble the first half dozen scales.
Dyeing veneer requires the following process. RIT dye is the only dye found to work. It is used one packet per gallon of distilled water. Don't use yellow, just find yellow veneer. Red is the slowest dye to penetrate. The water temperature needs to maintained at 180° F. Every half hour the veneer should be flipped. This agitation is an important part of the process. A drop of soap helps the dye penetrate the veneer. Don't let the veneer sit on the bottom of the vessel. The dye can be mixed separately in a smaller portion of water (at the same temp as the bath) and then added. Be sure all is dissolved or spotting will result. The dyeing process is complete when a small piece broken off shows color completely through the veneer. Shock the veneer by dropping the temperature to 32°. Press the veneer between towels and change the towels until they remain dry.
Sand shading was also discussed. This is usually used to create shadows in the picture. Use silica sand, 220 grit, from sand blasting. The sand should be heated to 600°. The piece of veneer is moved through the sand for a controlled burn. Typically this is done to one piece in a packet after cutting the joint to be shaded. The burning removes all moisture, so the part is touched with a sponge on both sides and stored under the cutting mat for 5-10 minutes.
The blue tape should be removed perpendicularly to the grain in order to minimize pulling the wood fibers up.
Yellow or white glues should be used for non-industrial veneer application, especially marquetry. Plywood is not a good choice for backing veneer. The grain in plywood can telegraph through the veneer. Particle board is too chippy if joinery is required, but is fine for pictures. Solid wood is a good choice. If applying sheets of veneer the grains should go in the same direction. The best choice is using the same veneer as the wood underneath. This can look like inlay when done correctly. MDF and HDF are also a good choices. Sometimes MDF can have a waxy surface. This needs to be removed with 220 grit paper. Finally, veneer has to be balanced; veneer on one side needs to be balanced by veneer on the other side, unless the board is held mechanically from the other side. Veneer should go in the same direction on both sides or one side may crack. The same glue and veneer thickness should be used.
Repairing marquetry and parquetry pieces can be done in multiple ways. Wood filler can be used for tiny holes. This should be sanded lightly with 150-grit paper before gluing. Background is the most difficult to repair without revealing the repair. Another way to repair is by making a window. Put matching scrap under the window and move until the best match is obtained. Cut the scrap through the window with a knife at an angle to make the new piece larger than the window: scribe, remove, cut through. Put tape behind the window. Put glue in the window and add the patch. Press fit this new piece into the hole and roll it into place. Sometimes it is best to remove a small piece and put the new wood on the back. (In this case the background is the keeper.) Cut on the scroll saw, tape and glue.
Flattening veneer can be done with commercial solutions, but these only last about four days. These solutions are tightly guarded secrets. Veneer Systems sells GF-20 or veneer softener. Don't use veneer glycerin from Rockler or Woodcraft. To use the GF-20 it should be mixed 50:50 with water. It is sprayed onto both sides of the veneer until it is dripping wet. The veneer can also be soaked for five minutes. After wetting the veneer press it between sheets of particle board for 1-2 hours. Veneer treated this way will cut well, eliminate chipping/tearing, feel wet, but can be glued.
Marc's method is permanent. Water, white glue, glycerin (Tractor Supply) and denatured alcohol are mixed in the ratios 1:0.5:0.25:0.5. It should look like milk. This mixture does not keep so any excess should be pitched. It doesn't like stain, but finishes fine. It can be brushed or sprayed onto the veneer. It is good for ornery woods. It should be applied thickly on both sides. The veneer should be hung for ten minutes. Marc uses fiberglass screen to separate the veneer sheets. The veneer is pressed between to layers of MDF. This can be done in a vacuum press. The layers are built up as follows: MDF->Scott towel->screen->veneer->screen->towel->screen->veneer->screen-> towel ... ->MDF. After one hour, three hours and five hours the towels need to be replaced and every two hours until the veneer is fairly dry. Before twelve hours is up the screens should be removed and the pieces should be separated with waxed paper followed by 1-2 days of continuous pressing. The wax paper is removed and the replaced with paper towels for an additional 3-4 days of pressing.
Water cannot be used to remove veneer tape if white glue was used to glue the veneer to the backing. Scraping is the best way to remove 80% of the tape. Use a big burr on the scraper to remove the tape and glue. Sand the entire surface while supporting the piece on carpet, minimizing scratches to the back. Start with 150 grit and keep sander moving. Sand the entire veneer, not just the places with glue or paper. When 90-95% of the paper is gone, switch to 220 grit. Sand back the same as the front. The best way to remove dust is by blowing.
Marquetry can be used in many places to provide decoration and value increase. Four to five 4" pieces are nice in a table top. The table top should be kiln dried to minimize warping. Resin glue should be used as yellow glue will allow the veneer to slip. The grain of the background veneer should be run perpendicular to the core wood grain. A slanted veneer edge is not desirable. The corners should be routed and covered. A step should be cut in the edge veener prior to routing to avoid tearout. Take care using white maple as MDF can be seen through it. Two layers of veneer should be used in this case. Apply veneer to the edges prior to the faces.
When making letters with marquetry flip the tracing so the letters come out correctly oriented.
Remove the damaged piece of marquetry with an exacto knife. Don't cut into the core. Scrape out any excess glue. With a clean hole do a rubbing with pencil on tracing paper to capture the desired shape. Put the tracing paper on the replacement veneer and score along the traced lines with the knife. The new piece should be slightly bigger. It can be used to carefully enlarge the hole. Paint the inside of the hole with glue using the knife and pop the piece into place. Use an acrylic sheet to clamp directly over the repair.
Clamp one face at a time. Press the face down. Consistent pressure is the key. Clamping cauls are a necessity. A center clamp should be applied first. Additional clamps are applied so the pressure works its way out from the center. A vacuum press avoids clamping challenges.
Finishing marquetry does not include stains. Marquetry should not be stained. It should be sanded to 220 grit. Poly is not recommended as it will yellow over time. Similarly, shellac is not used as it has color from the beginning. Clear water based finishes are acceptable, though care must be taken if white glue was used. The best finish is clear lacquer that contains a UV inhibitor. This will keep your piece the longest. Spray on three coats of semi-gloss (45 on a scale of 0 to 100) and don't display the piece in direct sunlight.