Soundboard fibre tear out

[Bullet]

Hi all,

What's the best method of stopping soundboard fibre tear out when applying binding / purfling tape?

Shellac coat prior?

I want to avoid my experience when "protecting" the soundboard during binding routing, where I slapped standard making tape longitudinally down the soundboard. Beautiful clean binding / purfling channels with no marks where the router base had been ...... Then I lifted the tape

Cheers Jason

[colburge]

Hey

I think the guys would probably say to use a down cut router bit and shellac.

Cheers

Col

[Bullet]

Cheers Col, the routed binding / purfling cuts were fine

The drama was the soundboard fibres lifted when I unpeeled the tape (from the centre of the soundboard).

Maybe cheap masking tape but probably need that first coats of shellac so the fibres don't lift

[colburge]

Cheers Col, the routed binding / purfling cuts were fine

The drama was the soundboard fibres lifted when I unpeeled the tape (from the centre of the soundboard).

Maybe cheap masking tape but probably need that first coats of shellac so the fibres don't lift

Didn't read that right, sorry. What was the purpose of the tape? To stop the SB getting marked from the router base? I've only made the one guitar and didn't have that problem, I used an expensive 3M tape that was around $12 a roll, and no shellac, so maybe that was the difference.


Cheers

Col

[Bullet]

Yes just added the tape to stop the SB getting marks. I have some good lmi binding tape which seems to adhere better and then come away from the Sitka spruce easier also.

Will do some test tapes and see what happens. Think it's better too when the tape is 90 degrees to the grain.

Cheers jase

[auscab]

Hi Jason,
I have seen people peel the tape off the roll then stick it to their clothing , jeans or shirt.
The tape is then peeled of and used. it makes a big difference to its sticking ability.

If you don't have double sided tape in your stash yet ,get some and try sticking felt or paper to the under side of the trimmer
there are a lot of other good uses for the double sided tape as well.

I have used a heat gun to warm plain masking tape when it gives me problems coming off.
If it [ Masking tape] ever gets clamped down under cauls when holding veneer together it makes it very hard to get off the next day. heat and sometimes turps are needed. I don't think turps in a guitar top would be a good thing though

[Philstix]

I don't know what you have available there but here in the states we have a thing called blue painters tape. It is a lower adhesion masking tape meant to protect against lifting old paint when masking between walls or a wall and a ceiling. I have used it many times and never had a problem with it lifting splinters on either spruce or cedar. Just to be safe I always try to pull off the tape at an angle to its length, that is, if the tape were put on at right angles to this page like this line of script I would apply the pressure to remove it towards the bottom right of the page. I'm not sure that is really necessary but why take chances. It is a little more expensive than regular masking tape but very cheap as insurance against ruining a top.

[kiwigeo]

1. a coat of shellac on the top.
2. tape aligned so its not running directly across the grain (not the advice given above but its the way I was taught to do it and Ive never had tear out).
3. use quality tape. I use LMI binding tape and have never had problems.

Correction 2. should read neither across or with the grain. ie oblique to the grain.

[Trevor Gore]

Apply a couple of coats of shellac before cutting the binding channels. Generally, you'll need to use fairly high tack tape when you put the bindings on and shellac protects against tear-out even when using the glass filament packaging tape that I use for taping bindings on. Pull the tape off at a low oblique angle when the time comes, as Phil suggests.

Note: If shellac stops tear-out (as it does) with these aggressive tapes, it's obviously strengthening/stiffening the wood quite a lot.

[ozziebluesman]

Yep a few coats of shellac prior to binding dose the trick. I use the Stewmac binding tape because its nice and strong, sticks well and I can then put firm tension onto the binding for a nice tight fit in the binding channel while the glue dries. When dry take care taking the tape off and you should have a nice job with no gaps.

Cheers

Alan

[inoz]

I shellac the top, tape on & off obliquely but also use a hair dryer when removing the tape.
Tape off, ow, shit that burnt, tape off, shit, tape off, shit shit
But no tear out

[Bullet]

Thanks all for your advice

I've completed the purfling and bindings and removed all the lmi tape. Basically ok, using a hair dryer made a huge difference. Got a funny look from the wife when sneaking it out to the shed though..,,

Will definitely shellac prior to cutting binding channels in future

Cheers

Jason

[Taffy Evans]

If I get this right you are concerned about the router base leaving marks on the top. On some jobs, especially repairs, I put the tape on the router base.

[nnickusa]

I always put blue painter's tape on the base of my router, stew-mac circle cutters and micro base. easy insurance against scratches and al-coloured staining....

[Bullet]

Tape on the router base ! Great idea, not sure why I didn't think of that !!

Will do that on the next guitar and the shellac coat too?

Cheers

[Bullet]

All,

Any ideas for an easy way of filling the grooves left by the initial tape damage?

[Beau Hannam Guitars]

Sand to 120 or 180(ish)
wash coat of Shellac (helps with router tear out)
Use Down cut spiral router cutters
Pull tape off slowly across the grain or slightly in the opposite direction of any grain runout (helps with fiber lift)

[Beau Hannam Guitars]

Also,
I think quality of tape has little to do with fiber lift.
High tack/strong stickiness is not great, but is unrelated to tape cost/quality.

Low strength/thin tape is annoying as the tape breaks. Again, unrelated to cost.

There is only a few thousands of an inch between thin and thick and really nice perfect tape.

The brown stew mac stuff is nice non breaking but it has no stretch which is good for a few things, like extra pull. Try some local brands. You will use it all eventually. Don't pay $12 a roll though.

[Nick]

All,

Any ideas for an easy way of filling the grooves left by the initial tape damage?

Not sure I get what you mean exactly, tape alone shouldn't create "grooves", is it just lines inbetween where the tape was sitting (i.e. it hasn't lifted the grain?) or has it torn out grain fibres?
If they are genuine 'grooves' and they aren't too deep or the fibres broken, you could "steam" them out, just put a damp rag over the area and use either an iron or a soldering iron (if the grooves are small) to create steam which should lift the fibres.

[kiwigeo]

All,

Any ideas for an easy way of filling the grooves left by the initial tape damage?

Not sure I get what you mean exactly, tape alone shouldn't create "grooves", is it just lines inbetween where the tape was sitting (i.e. it hasn't lifted the grain?) or has it torn out grain fibres?
If they are genuine 'grooves' and they aren't too deep or the fibres broken, you could "steam" them out, just put a damp rag over the area and use either an iron or a soldering iron (if the grooves are small) to create steam which should lift the fibres.

Nick,

It sounds like the wood has torn out along the grain. I get it quite a bit with Engleman.

Steaming sometimes works. Some people make up a filler using dust from the top plus either superglue or epoxy....with variable success. Important to test the filler out on scrap before using on the top. Also watch out for staining of light coloured wood when using superglue.

If all the above doesnt work then I just tell the new owner of the instrument that the tear out is proof that the top is genuine Engleman

[Taffy Evans]

Another way could be to spray or finish the top as normal and where the finish sinks into the grooves, drop fill with the lacquer and sand /polish level. I had similar marks in a Cedar top recently and using th e above method I can't find them now.
Cheers

[auscab]

All,

Any ideas for an easy way of filling the grooves left by the initial tape damage?

I would be checking the floor or the bin for the tape that was pulled off the job.
With a bit of luck the missing pieces should still be stuck to it , they are the best solution for a blind fix.

If that does not work out , patch it with matching wood, matching the grain direction as best you can.

A picture of your problem would be interesting to see as well.

[Bullet]

Sorry guys I didn't explain the problem well - the tape was put down on the soundboard and when I lifted it, up came fibres of the Sitka spruce leaving horrible grooves in the soundboard.

Having now tested the shellac coat I will be definitely be finishing the top better and putting the shellacked coat on prior to cutting the binding channels next time ...

Guitar no. 3 is going to be a lot better ......

Jase