Light Bridges

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Petecane
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Light Bridges

Post by Petecane » Thu Apr 25, 2019 7:21 am

I am always reading various blogs about fitting a light bridge.
Having lashed out on Koa for my Tenor Uke, I do not want to make a mistake.
What confuses me is that top grade classical guitars are fitted with ebony bridges which kinda makes a mockery out of the concept.
Can someone please enlighten me?
Even better to suggest a suitable wood for the Tenor bridge.
Many thanks in advance.
Petep

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kiwigeo
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Re: Light Bridges

Post by kiwigeo » Thu Apr 25, 2019 8:34 am

I avoid ebony bridges on my classicals. Rosewood is a better choice. I'm also building Gore style so the bridge is reinforced with carbon fibre which means you can use less dense woods with success.
Petecane wrote:
Thu Apr 25, 2019 7:21 am
I am always reading various blogs about fitting a light bridge.
Having lashed out on Koa for my Tenor Uke, I do not want to make a mistake.
What confuses me is that top grade classical guitars are fitted with ebony bridges which kinda makes a mockery out of the concept.
Can someone please enlighten me?
Even better to suggest a suitable wood for the Tenor bridge.
Many thanks in advance.
Petep
Martin

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Mark McLean
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Re: Light Bridges

Post by Mark McLean » Thu Apr 25, 2019 12:04 pm

Too much weight is generally thought to be a bad thing in a bridge. However, you need a wood that is really hard and resists splitting or denting. This is important around the saddle slot so that the forward tipping pressure of the saddle under string tension doesn’t snap out the front edge of the slot. Also important to have something tough enough to tie strings to, or to hold pins firmly. Although it is heavy, I think ebony has been a traditional choice because of its other attributes such as strength, stiffness, dimensional stability - and because black looks good. But lots of people have tried making lighter bridges from other hard woods and ebonizing them if you want them to look black. In North America a lot of people seem to be using pear or cherry or walnut. Here in Australia there are lots of hardwoods that have the right characteristics, and also look great. Things like mulga, gidgee, ironwood, tiger myrtle, blackwood can all do the job. As Martin said - making a wood and carbon fibre sandwich is a method proposed by Trevor Gore to make lighter, stiffer bridges. I would imagine in a uke the physical demands on the bridge timber are not as great as in a steel-string guitar, so you could probably get away with lots of different things. It mainly depends on how you want it to look. Check out some of Allen’s uke porn photos in the gallery for inspiration.

Petecane
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Re: Light Bridges

Post by Petecane » Thu Apr 25, 2019 12:36 pm

I will be using ebony fingerboard, nut, bridge saddle and tuning pegs so I think an ebony bridge is a must.
Either that or I dye some Gidgee which I have.
But I dont think I will be gaining much by doing that.
As t you say, a Uke bridge is a lot smaller.
I was just starting to get paranoid about lightness.
Thanks for the tips chums.
Pete

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kiwigeo
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Re: Light Bridges

Post by kiwigeo » Thu Apr 25, 2019 12:57 pm

Petecane wrote:
Thu Apr 25, 2019 12:36 pm

I was just starting to get paranoid about lightness.
A perfect bridge would weigh nothing....it's there to anchor the strings and transmit string energy to the soundboard.
Martin

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56nortondomy
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Re: Light Bridges

Post by 56nortondomy » Thu Apr 25, 2019 5:02 pm

Gidgee is pretty heavy too Pete, you might as well use ebony. I don't use ebony anymore, I use EIRW or blackwood now
Wayne

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lamanoditrento
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Re: Light Bridges

Post by lamanoditrento » Fri Apr 26, 2019 9:32 am

Gidgee doesn't take to ebonising well (I think Pete Curly has posted several times about it). Blackwood on the other hand with steeped tea (just Liptons) and iron acetate solution turns jet black and is much less dense. The below bridge came in at around 12 grams:
IMG_2050.JPG
IMG_0071.JPG
Trent

Petecane
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Re: Light Bridges

Post by Petecane » Sat Apr 27, 2019 7:39 am

Trent

Nice bridge!
Now some questions if I may?
Is your bridge made up or one piece?
Is that a Ukulele?
May I see the whole picture as I like what I have seen, your outline.
The Rosette is beautiful.
I will have to source some blackwood and also iron a acetate.
Do you mean Liptons Tea?
Please excuse my ignorance.
Pete

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Mark McLean
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Re: Light Bridges

Post by Mark McLean » Sat Apr 27, 2019 9:02 am

For iron acetate you go to the supermarket and buy a 2 litre bottle of the cheapest white vinegar that you can find. And while you are there grab some Liptons teabags, or Twinings if you prefer. Put the vinegar in a container with a lid (it is going to get smelly) and add a good handful of steel wool. Don’t completely fill it - you need some air in there as well. You can also chuck in any old steel/iron pieces like nails. Give it 2 weeks and the steel wool will rust and disolve into the acetic acid and you will have produced a solution of iron acetate. Strain it to get the crap out, then just store it for use later. This solution will stain various timbers a jet black colour (a process known as ebonizing). Not all timbers respond - it depends on the tannin content of the wood. Where the tea comes into it is that it contains extra tannin. If you pre-soak the wood in super-strong black tea it can increase the tannin content and get a stronger ebonizing reaction. But high-tannin timbers like blackwood or oak don’t always need the tea treatment, they can go black very quickly just with the iron acetate. It is a fun magic trick. There are lots of tutorials online about how to do it.

Petecane
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Re: Light Bridges

Post by Petecane » Sat Apr 27, 2019 10:03 am

Mark.
Many many thanks for that tute.
I was oblivious to this.
It sounds like an A. Stradivari secret!.
I am very grateful to be let in on this.
I will now get very excited about being a chemist.
Smells are brilliant but so long as doesn't go " Bang" !
My father in law, now 92 was a very clever chemical scientist and he told me several stories of things going " Bang".
He worked for the military whereas eventually there was a " Bang" imminent. ( that's as far as I will go before contravening the official secrets act)

You could see the boy in him with his cheeky smile.
Anyway Mark.....
BRILLIANT .....and thanks.
Pete

Petecane
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Re: Light Bridges

Post by Petecane » Sat Apr 27, 2019 11:23 am

Just noticed the six strings Mark.
Sorry!.....Aghhhh
Pete

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lamanoditrento
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Re: Light Bridges

Post by lamanoditrento » Mon Apr 29, 2019 7:40 am

Petecane wrote:
Sat Apr 27, 2019 7:39 am
Trent

Nice bridge!
Now some questions if I may?
Is your bridge made up or one piece?
Is that a Ukulele?
May I see the whole picture as I like what I have seen, your outline.
The Rosette is beautiful.
I will have to source some blackwood and also iron a acetate.
Do you mean Liptons Tea?
Please excuse my ignorance.
Pete
Thanks Pete. Yes it is one piece. It is a small parlour guitar based on the Torres 2 plans in Roy Courtnell's book Making Master Guitars. Lots of pics on this tread viewtopic.php?f=25&t=7912&p=85651&hilit=silky#p85615

Yes, just normal tea. Someone here once posted this link, which I found very useful https://www.popularwoodworking.com/tech ... zing_wood/

Mark is right, tea might not have been needed on blackwood but I am sure it doesn't hurt.

Also, I recommend you don't put a lid on too tight on the steel wool mix as the reaction produces a bit of gas and you can end up with an exploding jar (bit like bottling homebrew too early :oops: )
Trent

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WJ Guitars
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Re: Light Bridges

Post by WJ Guitars » Mon Apr 29, 2019 8:42 am

I have never tried ebonizing timber. How deep does the colour change go into the timber?

Wayne
https://wjguitars.wixsite.com/mysite-1

Petecane
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Re: Light Bridges

Post by Petecane » Mon Apr 29, 2019 9:34 am

Wayne.
I haven't either yet but it sounds like good fun.
I read the link that Trent posted and it seems depending on how it is applied, the ebonising goes right into the wood fibres.
The guy makes a point in not burnishing the wood between coats as the solution will not then penetrate.
Trent can be more comprehensive as he has done it.
Trent.
Looked at your blog on your wife's parlour guitar.
The whole concept ,re wedding rings etc is very romantic and lovely.
I really like the shape.
I see you went for pegs as well.
I especially love pegged guitars.
But you should not have to push them too often.
I use Hills Peg Paste which helps enormously.
It gives them so much character and also keeps the neck light which makes for easier playing.
There is nothing worse than the neck dropping when you change positions.
With full size guitars not such a problem as the body sits okay to the human form but a heavy neck on a Uke is a pain.
Gorgeous guitar build.
Love it to bits.
Pete

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Re: Light Bridges

Post by blackalex1952 » Mon Apr 29, 2019 1:24 pm

I made this rosette using a few tricks...firstly ebonised pearwood, then I used gold MOP and Walnut. The Walnut is a lot softer than the MOP so I saturated the walnut with superglue to harden it up so that I could scrape the rosette flush.
Another good trick I have used for restoration work is to use potassium permanganate to age wood. (Condes crystals)
Here:https://www.youtube.com/watch?v=tViTWUL8Was
I restored a 1910 Gibson L-1 last year and used the potassium permanganate to give the aged look to some back braces and liners that I replaced, along with some veneers which stabilised cracks in the back of the instrument. The damage was caused because "someone" had left the guitar leaning on a couch in front of an electric radiator. Moral of story, don't lend a 1910 L-1 to a couch potato! Cheers! Ross
"Everything I say on the topic is based solely upon inexperience and assumption!"

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Re: Light Bridges

Post by blackalex1952 » Mon Apr 29, 2019 4:10 pm

blackalex1952 wrote:
Mon Apr 29, 2019 1:24 pm
I made this rosette using a few tricks...firstly ebonised pearwood, then I used gold MOP and Walnut. The Walnut is a lot softer than the MOP so I saturated the walnut with superglue to harden it up so that I could scrape the rosette flush.
Another good trick I have used for restoration work is to use potassium permanganate to age wood. (Condes crystals)
Here:https://www.youtube.com/watch?v=tViTWUL8Was
I restored a 1910 Gibson L-1 last year and used the potassium permanganate to give the aged look to some back braces and liners that I replaced, along with some veneers which stabilised cracks in the back of the instrument. The damage was caused because "someone" had left the guitar leaning on a couch in front of an electric radiator. Moral of story, don't lend a 1910 L-1 to a couch potato! Cheers! Ross
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"Everything I say on the topic is based solely upon inexperience and assumption!"

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Mark McLean
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Re: Light Bridges

Post by Mark McLean » Tue Apr 30, 2019 5:50 am

WJ Guitars wrote:
Mon Apr 29, 2019 8:42 am
I have never tried ebonizing timber. How deep does the colour change go into the timber?
Wayne
Not very deep. It probably depends on the porosity and thickness of the piece, but when I ebonized an entire neck (blackwood) I found it only penetrated about 1-2mm. This is basically a finishing step. You need to have your piece fully shaped and sanded before you apply the ebonizing solution, like Trent did with his bridge. Wetting it with the tea and iron acetate will probably raise some grain, and necesitate a further final sanding. If you happen to sand through the black layer into underlying natural wood you can just apply more ebonizing solution and make it uniform again.

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lamanoditrento
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Re: Light Bridges

Post by lamanoditrento » Tue Apr 30, 2019 7:57 am

That was very interesting. Straight to the bookmarks
Trent

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Mark McLean
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Re: Light Bridges

Post by Mark McLean » Tue Apr 30, 2019 8:01 pm

Yes, that is a really nice discussion of wood toning. Thanks for the link.

Petecane
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Re: Light Bridges

Post by Petecane » Sat May 04, 2019 4:42 pm

I am really impressed with this iron acetate thing.
My brew is only two days old and pretty black already so I thought I would just dip a piece of wood in it to see what happens.
Yep.....it went black!.
...well a really dark tone of grey with just one dip.
After two weeks the brew will be stronger and blacker.
This forum is brilliant.
I really enjoy being an industrial chemist.
Pete

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Dennis Leahy
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Re: Light Bridges

Post by Dennis Leahy » Thu May 09, 2019 5:12 am

Another option is to use Quebracho bark powder as the "tea" to add tannin to wood. Quebracho bark is very high in tannins. That powder is used in leather tanning, so check leather/tanning suppliers, or of course ebay.

The ferrous acetate will often make the wood a dark charcoal gray, maybe with a hint of blue, the first time. Let the first coat dry, then give a second coat of ferrous acetate, to get the wood closer to black.

The chemical change is only on the surface of the wood - depending on the wood's absorbancy and oils - I'd figure it to be no more than 1/64" (less than half a mm) deep, so you can only do light sanding after treatment.

There used to be a wood product on the market called "Ebonex", which was (American Black) walnut wood that had been (vacuum) pressure treated with ferrous acetate. It was black all the way through - even 3/4" (19mm) thick pieces. It looked exactly like high-quality Ebony in woodworking projects, with none of the Ebony problems or cost. "One of these days..." I'm going to vacuum/pressure treat some 1/4" thick Walnut pieces, (then sand to .200" and add contrasting veneers), and slice bindings out of it. Then I will laugh and rejoice when bending my faux-Ebony bindings into Venetian cutaways! (For bridges, I'd need 1/2" thick vacuum treated blanks.)
Another damn Yank!

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