Posted on June 6, 2024May 27, 2025 by Dale Phillips Questions: Post Buffing Finish Scratches Questions: Post Buffing Finish Scratches by Brian Boedigheimer Originally published in American Lutherie #86, 2006 See also, Questions: Power Buffer For Finish by Charles Fox Brian Boedigheimer of River Falls, WI responds to Mario’s question in AL#79 regarding what to do about tiny scratches in finish noticed after buffing: Charles Fox responded earlier to discuss lighting and I certainly agree lighting is key in so much of the work we do. Another thing to consider is the grading system of the abrasives one chooses to level the finish. There are three systems: CAMI, which is the U.S. standard grading system; FEPA, the European standard; and Micron grading. FEPA P800 is equivalent to CAMI 400. The P indicates the FEPA grading system, which is important because the grit particles are more uniform than in the CAMI system. Therefore there’s less chance of a stray large particle causing a scratch that we won’t see until buffing. So P800 gives you the cutting action of a 400 grit without the stray (larger) particles of the CAMI rating. Micron has the tightest tolerances for particle size, and if you have access to Micron-graded paper, that’s even better than FEPA. The equivalent Micron grade would be around 25 or 20. I recommend the FEPA grading system for abrading coatings until you’re into compounds; then you’re dealing with Micron. When sanding to level finish, the coarsest grit I would use is P400 grit, but typically I start with P600 or higher. I used to go through the process level-sanding with 320, 400, 600, and so on. The problem is, if you miss a 320-grit scratch working through the higher grits, you won’t know it until you buff out the guitar, and only in the right light will you see it. Now when I level-sand my finish before the final coats, I use P800 and spend just a little extra time with that one grit. It really doesn’t take me much longer, and I know those tiny scratches won’t suddenly appear. Then I spray the final two or three coats. Once that’s cured, I only have one grit of wet sanding to do before buffing. At that point I choose P1200. Don’t think that because each layer of nitrocellulose lacquer melts into the previous one, you won’t have stray 320 scratches show up. Even with that specific bond, a stray particle scratch from 320-grit CAMI-graded paper will show up when buffed out. I’ve experienced it. ◆
Posted on March 4, 2024May 8, 2025 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, 2024May 16, 2025 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, 2024May 15, 2025 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 August 1, 2022May 19, 2025 by Dale Phillips Potassium Dichromate, Oxalic Acid, and Carnauba Wax Potassium Dichromate, Oxalic Acid, and Carnauba Wax by Jeffrey R. Elliott Originally published in Guild of American Luthiers Data Sheet #52, and #55, 1977 and Big Red Book of American Lutherie, Volume One, 2000 Potassium dichromate. European luthiers commonly use potassium dichromate to give that nice, brown “aged” look to lighter, newer woods. It can be used by itself or mixed with aniline dyes for additional color tints. Primarily it has been used to darken the interiors of violin-family instruments, although I know of many who have used it on the exterior to darken spruce and maple. I have used it both inside and out to create a “naturally aged” looking wood on guitars. Potassium dichromate is a chemical activated by light from the sun, sunlamp, or infrared lamp, but direct, natural, full-spectrum sunlight is best. Beware: Indirect light will not activate it, and the solution will tend to color the wood a murky green. The solution is rather weak — two tablespoons to one gallon of water. It can be applied by brushing or by wiping it on with a cloth (wear gloves). Although I have never tried it, I imagine a spray method would work as well. Whichever method is used, a light, even coat is recommended. 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.
