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John Mosconi of Sting King Lutherie in Akron, Ohio takes us on his journey of refinishing this mandola.
Step 1: Prep and Sealing
The key to any successful refinish is prep. To prep the mandola, John sanded the bare wood with 320 grit paper, applied 3 to 4 coats of General Finishes Enduro Water Based Lacquer and sanded it level with 600 grit dry paper.
Step 2: Spraying the Body
The body of the mandola was refinished in a sunburst design. To achieve this look, John masked of the binding with 1/8 or masking tape and applied the light amber color first. The amber toner was made with 10 oz. of Enduro Lacquer, 8 oz. of water and 6-7 drops of Amber Transtint. The mixture was strained (very important!) then sprayed using light coats. The darker brown color was achieved with the same ratio of Enduro Lacquer and water and oz. or Dark Mission Brown Transtint and 2 drops of Black Transtint. John discloses that the key to producing the sunburst pattern is to set the spray gun to allow for higher airflow and less material. The spray gun tip should be adjusted for a round pattern and you should aim for only the outer edges. It's also best to clear coat the amber color to seal it before you spray the perimeter and sides. This mandola also received a coat of Tobacco Brown Transtint over the amber to give it a richer antiqued appearance.
Step 3: Apply Clear Coat
Applying a clear coat is imperative to the refinishing process as it brings out any blemishes or imperfections that may need blending. First John removed the masking tape and scraped away any over spray. John says, "I then applied about a dozen thin to medium coats of clear coat, using 600 grit dry paper, sanding every 3-4 coats to remove imperfections. This is normally done over 2-3 days."
Step 4: Leveling and Sanding
After the mandola cured for 4-5 days, John sanded for the final time in order to buff. He dry sanded by hand with 1500 grit sanding paper. John recommends the Mirka brand in a 5-inch disc, which can be found at auto body supply shops. If you're unable to find the 5-inch disc, John suggests using the Mirka Double Density sanding block and cutting it down to a 2x3x5/16 size. After dry sanding, he wet sanded with 1500 grit paper dipped in soapy water, followed with 2000 grit paper. An alternative to this sanding technique is to dry sand only with 1200 grit 3M Hookit Finishing Film (part #952) and go directly to the buffer. John recommends this high-end industrial sandpaper, if you can find it, because it eliminates the intermediate wet sanding step and it produces a scratch free glossy finish with minimal work.
Step 5: Rub Out and Polishing
During this final step John buffed with a pedestal buffer using a Menzerna medium and fine compound. If you don't own a pedestal buffer, John proposes substituting with Mezerna #1 and #2 paste compounds and applying them with a cloth or buffing pad.
John has also used Emtech 6000; a water based production lacquer to refinish instruments, but is now a bigger fan of GF Enduro Lacquer. John says, "I noticed that the GF Enduro seems to cure faster and you can leave water drops on it after only 48 hours and it doesn't eat into the lacquer. At this point the EmTech would still show marks. Also, I can polish the GF Enduro with a cream polish like Novus 2 and it buffs to gloss, whereas EmTech would get cloudy. This means that a customer can safely polish and clean their instrument with most quality polishes and be fine. The GF Enduro looks like most quality factory finishes, not too thick, not too thin. Lastly, it sands with the 3M finishing paper and buffs scratch free noticeably faster and easier than the EmTech, so of course the final steps are much faster."
The end result is truly outstanding! It's one beautiful mandola! String King has been a full service lutherie shop in Northeast Ohio repairing guitars, basses, mandolins, banjos and violins since 1989. They offer everything from minor repairs to refinishes and restorations and custom conversions. They also offer handmade acoustic guitars. Visit them at http://stringkinglutherie.com/ for more info.