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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

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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.

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Spray Gun Agitator

Spray Gun Agitator

by Jimmie Van

Originally published in Guild of American Luthiers Data Sheet #91, 1978

 

A new product that I found to be most helpful when spraying a finish or other things that had to be in complete suspension to assure uniform coverage, is a agitator siphon cup assemble sold by N.A.P.A. auto part stores. This cup will work on most major brand guns. The 1 quart cup provides constant agitation from air right off of the same line that your gun works off of, no extra line is needed. You can control the mixing speeds of the agitator, and does not require an extra cleaning. The part number you need to ask for is model 70-707. This may be of big help to those of you who do a lot of finishing work. ◆

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Glass Jars for Spray Guns

Glass Jars for Spray Guns

by Tim Olsen

Originally published in Guild of American Luthiers Data Sheet #91, 1978



Commercial spray guns, such as the DeVilbiss type MBC, typically use aluminum cans to hold the juice. Aluminum cans are lightweight and unbreakable. They are also expensive and inconvenient, in that they must be labeled; the contents can not be viewed without uncorking the cans.

By substituting glass jars for the aluminum cans, many advantages can be realized:

Jars are cheap.

Jars are clear, allowing one to observe the contents instantly, and to check for sediments, precipitates, jungjills, farfles, and other forms of grungus.

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Questions: Tru-Oil Finishes

Questions: Tru-Oil Finishes

by Jeff Jewitt

Originally published in American Lutherie #90, 2007

 

Eric Nicholson of Northern Ireland asks:

Woodworker magazine published an article on Stewart Adamson’s work regarding Tru-Oil finishes. His method involved a considerable amount of work with Micro-mesh during the process. I tried his method on my own guitars, both classical and steel string, with very satisfying results. Tru-Oil gives an attractive semigloss finish on all woods, but Adamson also goes on to say that for those that like a gloss finish, a gloss tung oil is now available only in the USA. Does anyone know of this gloss tung oil and where it is available in the States, or if it is now available in the UK?


Jeff Jewett of Homestead Finishing in Cleveland Ohio
responds:

Tru-Oil is not pure tung oil. It’s a mixture of linseed oil, mineral spirits, and, according to the manufacturer, “modified oil.” It’s arguable that no tung oil is even used in this stuff. When finish chemists talk about “modified oil” as an ingredient they typically mean either chemical modification or heat modification. Chemically modifying a drying oil involves reacting it with chemicals and heat to form what are known as alkyds, which are used in varnish manufacture. Heat-treated oils basically jump start the drying/curing process. Pure heat-treated oils are used all the time in making finishes, but they rarely show up as “finishes.” The only pure heat-treated linseed oil I know of is Tried and True “Varnish Oil.” Pure heat-treated tung oil is sold in this country under the Sutherland Welles brand (www.sutherlandwelles.com). So I would be tempted to say that Tru-Oil is a mix of linseed oil and some sort of modified linseed or tung oil. Because it has a high oil content, it is not possible to produce a very glossy finish. High oil (also known as long oil) products tend to form microscopic wrinkles at the surface as they cure.

There is one way to heat-modify pure tung oil so that it will form a glossy film. This involves careful and controlled heating of the oil to about 450°F. Very few people can cook tung oil properly nowadays, but you can buy it under the Sutherland Welles brand “Original Formula High Lustre.” I don’t know if they will ship overseas. It’s not an easy finish to do, and I’m not sure that it will match the gloss of a French polish, but at least you know it is real tung oil, along with solvent and some driers.