Tape Tear Out

[John Reid]

Almost ready to glue binding (i.e., binding and purfling). I’ve routed the channels on the back and that went well. For the top, I’m worried about tear out when both routing the top for the binding and using tape for gluing the binding.

In after some research, I think I know what I want to try and was hoping I could get some feedback to see if I’m on the right track.

Being new to all this, I wanted to do a simple finish for the whole guitar, so I was planning on using Tru Oil. So, I’m thinking that I could apply some Tru Oil to the top (Engelmann spruce) now. The goal is to 1) help reduce tear out from routing the channels and 2) help prevent tear out when taping the binding for gluing.

If I do apply Tru Oil now, will this be an issue later on with the bridge and fingerboard?

The picture shows a little test with tear out and 3 kinds of tape applied to bare wood (left) and wood with a coat of Tru Oil (right). The blue painter’s tape is awful. There is still some tear out with the green tapes, but not nearly as much.

Appreciate any feedback. Thanks!

[RHayes]

There are many varieties of "blue" tape. I always thought it was formulated for easy removal when doing traditional painting and doesn't have much holding power. How you remove it can greatly affect pulling up the fibers.

[carld05]

Pull the tape off at a 45 degree angle and/or heat it with a hair drier while removing. I wouldn't use tru-oil at this stage. It would be better to seal the edge of the top with shellac then sand it off before finishing.

[Skarsaune]

Pull the tape off at a 45 degree angle and/or heat it with a hair drier while removing. I wouldn't use tru-oil at this stage. It would be better to seal the edge of the top with shellac then sand it off before finishing.

+1. Pulling off at an angle is key. Did the binding on a 000 I'm building yesterday. I used the green tape but I've used blue before as well.

[tippie53]

I have learned that a spit coat of sealer or shellac will eliminate 99% of this
torrified is especially vulnerable to tear out. Seal coats also let the tape stick better.
Once done the sealer coat will sand off easily

[ruby@magpage.com]

#1 on the shellac and the removing tape at an angle. Just pad on a layer of shellac within a couple of inches of the edge, wait a minute, and put on a second coat. Also looks like maybe your bit is not sharp - here and in binding channels you should have a sharp bit.

[John Reid]

A lot of good input. Thanks.

I had heard about heating the tape, too. The picture shows my little experiment. I put pieces in the same area where I knew there could be some tear out. Heating sure makes a big difference!

Thanks for the heads up on the bits being sharp. The picture I showed was of the rough edges from a bandsaw rough-cut on the top. I just got a set of bearings and bit from SM, and that cut pretty cleanly on the back binding channels.

Yesterday I applied a very thin coat of Tru Oil on the edges of the top. Next, I’ll bend the binding, and after that rout the channels and glue. I'll use green tape and remove with some heat. Excited and nervous.

[Danl8]

Interesting how the heat seems to really help. I've been doing the edge coat of shellac like John does and it works for blue, green and orange tapes for me. Torrified tops are especially friable -- I might even add heat on my next one.

[phavriluk]

Not knowing any better (different?) I give each soundboard a coat of shellac before any router comes near it. Keeps fingerprints off, too. From my vast well of experience building six guitars, five from scratch, one kit. Worked out well for me.

[Stray Feathers]

I've followed the old practice of spraying shellac where the routing is to be done. But I am working on a spruce top guitar with "ebano" binding - black like ebony - and when sanded it stains the spruce. I think ebony is somewhat the same. So I now I wish I had sprayed the whole spruce top to keep it cleaner. And I might use vinyl sealer, since (we had this discussion elsewhere) the spray shellac I can get in Canada is not unwaxed, so is not so good under lacquer.