Posted on March 4, 2024March 5, 2024 by Dale Phillips Seedlac Seedlac by Nicholas Von Robison Originally published in Guild of American Luthiers Data Sheet #150, 1980 and Big Red Book of American Lutherie Volume One, 2000 Seedlac resin, when combined with alcohol, gives a magnificent spirit varnish suitable for spraying or French polishing with qualities far superior to its better known cousin shellac. It’s more transparent, faster drying, harder, and more resistant to scuffing and moisture. The latter quality is of particular value as sweaty hands can play havoc on a shellac-based finish on a musical instrument. With all this going for it, it is not well known or used by luthiers to a great extent. The primary reason is that the major paint and varnish manufacturers buy most of the crop for their own needs, leaving little for the small-scale importers. About 60% of the resin is collected from an area between Calcutta and Central India with lesser amounts coming from Myanmar, Thailand, and Laos. There is a distinct difference in the resin color from different areas. The lac west of Calcutta is yellow or orange, east and south of Calcutta it is red, a pale red in Assam, and a dark red in Thailand. The resin comes from various indigenous trees, primarily kusam (Scheichera trijuga) which has the best color (pale yellow) and quality, but others such as pala (Wrightia tomentosa), ber (Berrya amomilla), and ghont (Bursera serrata). Two crops occur each year, summer and winter, and they revolve around the life cycle of a scale-like insect (Laccifer lacca) which infests the host trees. This small (about the size of an apple seed) red critter was cultivated as early as 80 A.D. for the purplish dye it contains. But not until 1580, in the records of Akbar the Great, do we find any mention of seedlac resin for varnish making. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on March 4, 2024March 5, 2024 by Dale Phillips Chemical Stains Chemical Stains by Michael Darnton Originally published in American Lutherie #32, 1992 and Big Red Book of American Lutherie Volume Three, 2004 One of the biggest problems for the violin maker trying to replicate the effects of time is the imitation of the color of ancient wood. Even unantiqued instruments benefit from the rich appearance of old, time-darkened wood under a coat of fine varnish. Chemical stains have the greatest promise for replicating the look of old wood. Unlike aniline and pigment dyes which insert foreign colors into the wood, either in the form of a soluble dye or of a solid pigment, chemical stains cause a color change in the wood itself. The change is both permanent and clean-looking when compared to that of aniline and pigment colors. Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on March 4, 2024March 5, 2024 by Dale Phillips Honest Ron’s Lacquer Finishing Technique Honest Ron’s Lacquer Finishing Technique by Ron Lira Originally published in Guild of American Luthiers Data Sheets #262, 1983 and Big Red Book of American Lutherie, Volume One, 2000 Tools and Materials: High quality spray gun — Binks 69 Respirator and rubber gloves 1/2 h.p. or larger compressor 2 water traps in air line — Amflo 1060 Air regulator for 40 lbs.–50 lbs. static — Binks Hot plate with water tub Clean place to spray Air or electric buffer and pads Rodac 717 and Schlegel 875C pads 120-, 220-, 320-, 600-grit sandpaper 3M Tri-M-ite Fre-cut and wet or dry Behlen Pore-o-Pac paste wood filler Sherwin Williams T75C40 Finish lacquer Sherwin Williams T67F3 Vinyl sanding sealer Sherwin Williams R7K120 Thinner Sherwin Williams R7K27 Retarder Sherwin Williams D1T271 Rubbing compound Sherwin Williams D1T13 Polishing compound 3-M-05990 Imperial Hand glaze Become A Member to Continue Reading This Article This article is part of our premium web content offered to Guild members. To view this and other web articles, join the Guild of American Luthiers. Members also receive 4 annual issues of American Lutherie and get discounts on products. For details, visit the membership page. If you are already a member, login for access or contact us to setup your account.
Posted on March 3, 2024March 6, 2024 by Dale Phillips Miter Slot Sled Miter Slot Sled by John Calkin Published online by Guild of American Luthiers, March 2024 This jig is more fallout from the week I spent in the last century in a class taught by Charles Fox. Jigs with clamps such as these have been all over my shop since then. On top, the jig is nothing more than a panel of MDF, two lengths of 1/2" threaded rod, a pair of knobs, and two “jaws” cut from steel flat stock. The jaws were placed in a vise and one end was bent into a slight hook with a hammer. As you will see, aluminum might have been a better choice. The underside of the jig is nothing more than randomly placed, recessed tee nuts and a wooden runner that fits nicely into the miter slot of the table saw. The runner left the panel overhanging the blade slightly so that a zero-tolerance saw cut could be made. All layout is done on the object to be cut. Lines are placed on the edge of the jig, clamped down, and gently run through the blade. Rough lumber can be given a clean edge as long as the dimension is within reach of the saw blade. BEWARE OF THE BLADE TOUCHING THE STEEL JAWS. THE RESULTS COULD BE DISASTROUS! Aluminum jaws make much more sense in this context. Note that helper blocks are needed to cut tall stock, in this case a pair of ukulele neck blanks. Make the cut slowly to prevent moving the stock, especially if the blade is less than newly sharpened. Since this is the maximum depth that the saw can cut on this jig, the threaded rods were marked for length with a piece of masking tape, then cut back with a hack saw. ◆
Posted on March 3, 2024March 6, 2024 by Dale Phillips Mask for Belt Sanding Mask for Belt Sanding by John Calkin Published online by Guild of American Luthiers, March 2024 My 6×48 belt sander is my favorite and most used machines, though getting the most out of it didn’t come easy. It takes a knack to use one accurately, and that took years to develop. Perhaps most importantly, I learned to join plates and sculpt necks, saving myself scads of time over the years. This tip is about sanding parts on nearly completed instruments. It can be dangerous because the plates are already as thin as desired. In this case I needed to take down the end blocks of a dulcimer to the level of the plates. I had already shaped the sides of the blocks using a disk sander and sanding blocks. I used a scrap of poster board to mask the plates as I took down blocks to meet the plates. The end blocks weren’t that much oversize. A hand plane might have done this job as fast as my belt sander, But I never use handtools if a machine will do the job. Whew! I cut it close on this one, but it’s OK. The back of this dulcimer was already thinner than I liked. The block on the bridge end has to be larger to make room for some sort of string fixtures. There are also blocks inside the dulcimer to support the end blocks. The mask doesn’t have to be fancy or cover the entire plate. Sanding the block is done in quick steps with visual checking at every step. No sweat this time. All of the hand pressure on the sanding belt is applied to the block. I usually keep 80 grit belts on my sander. Sixty-grit would last longer and cut faster but the scratches require more work to remove. The abrasive barely touched the mahogany on this end. Most belt sanders of this size come with a 9" disk sander attached, but right from the factory mine wobbled badly. It was also frequently in the way, so I dismantled it. I considered returning the machine to Woodworker’s Supply, but repacking it would have been a lot of work. They still sell this machine. If they haven’t improved I wouldn’t buy it again. Standing the belt 90 degrees to the supplied work table turned out not to be a big deal, so I didn’t miss the disk sander very much. ◆
