epoxy application

[sir juice]

i've decided to use epoxy to finish my fretless neck because i use roundwounds and want to reduce damage to the neck as much as possible (i know about change of tone etc. and i don't want to go for standard fretless tone so thats not a problem to me)

but the actual application has got me stumped. i know you get epoxy in those 2 part sets of resin and hardener, which of these do i use? or both? or something completely different? and what is the actual process within the application itself.

[62bass]

I've used epoxy for this application a couple of times and it's worked well. I don't use any of the 2 part glues as they are too thick. I used a 2 part epoxy coating sold in hardware stores for coating bar tops. It costs about $40 around here and the smallest size is way more than you need so there will be some waste. The stuff has a shelf life of only about a year. It's thinner and penetrates the wood better before setting up. You must use both parts in the recommended ratio. The bar top stuff was a 50/50 mix of resin and hardener. Some of the 2 part epoxy coatings sold for marine applications will work well too. Brands such as WEST and System 3 are good. Check a store that sells sells materials for kayak and canoe builders. They always have it. System 3 also sold a test kit advertised in Wooden Boat magazine which is a smaller amount. They may still do so and that might be cheaper but you'd have to order by mail.

Luthier Michael Dolan has recommended using polyester boat laminating resin and says it gives a harder final finish. It's available from good marine supply stores. I've used it before for repairing fiberglass boats. It sets up quite quickly.

It's a lot of work to get a clean job. You must mask off the neck to prevent drips from sticking forever. Use a plastic tape. The stuff takes about 12 hours at 70 F to harden enough for a second coat. Sand with 400 grit paper on a level hardwood block before the second application. After the second coat had hardened for a couple days, I sanded again with 600 grit paper and water to get a perfect satin finish. Epoxy takes about a week or so to really harden up. Temperature plays a big part.

There is a recent thread somewhere here detailing the use of super glue to do the same thing. It looks easier and may give superior results but I haven't tried it.

If you go the epoxy route, do a test run on a piece of smoothly sanded scrap wood like a piece of birch or maple that you can buy in short pieces from Home Depot. Buy a few cheap natural bristle brushes to apply it. Don't use synthetic brushes or foam brushes as they will dissolve in the mixture and really give you a mess. Of course you should have the neck supported in a level position so you don't get runs or sags on the fingerboard. You only need a very small amount for each application, say 2 oz. or less. Don't get any of the epoxy in your eyes, wear gloves to keep it off your hands and discard the used brushes and leftover mixture in the trash after it sets up. Follow the manufacturer's directions for mixing.

[miguel2u]

I am in the process of epoxying a cheapo bass fretboard. Before I started, I measured the fretboard radius with a gauge and discovered that the fretboard had grooves and flatspots in it. I bought the corresponding radiused sanding block from Stewmac and sanded the board to a constant radius. The first coat of epoxy soaked in in some areas leaving an uneven surface. I sanded back to a constant radius, checking with a radius guage. I wait about 4-5 days of curing before sanding. I am using 100 -180 grit for rough shaping and will move to finer grits later. The low spots will remain shiny during the sanding process.

Pop bubbles with a pin while the epoxy is still liquid. Otherwise the big bubbles leave deep depressions that take forever to sand out. Guess how I know :-)

Do get a radius gauge and the corresponding radiused sanding block as it is very easy to sand flat spots, depressions etc.

[62bass]

Oh yes, the bubbles. One easy way to handle them is to use a hair dryer on low setting and play it over the fingerboard lightly as soon as the bubbles develop. They'll pop and level out easily.

A radius block is nice to have. I didn't need it because the fingerboard was in good shape and needed only light sanding with fine grit paper on a sanding block to get ready for the epoxy. I worked carefully so as to not alter the radius. It's not all that hard to do.

[miguel2u]

Hair dryer...good idea. I will try that next coat. Heating the resin container in very hot water also helps.