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RE: Several things I am curious about the guitar.   You are logged in as Guest
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Piwin

Posts: 2087
Joined: Feb. 9 2016
 

RE: Several things I am curious abou... (in reply to estebanana

Vodka? Clear spirits are for pussies who need a saddle to play flamenco.

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"When I'm dead, I'm going to forget everything – and I advise you to do the same."
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 24 2018 15:51:21
 
estebanana

 

Posts: 7497
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RE: Several things I am curious abou... (in reply to Piwin

I don't know about that- but if this entitlement to back talk the practicing guitar makers while asking for free information about guitars continues, I'm going see that as a sign that it's time to do another fund drive for Simon. You know the' free service' administrator who so graciously runs the site.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 25 2018 1:09:59
 
Tom Blackshear

 

Posts: 1794
Joined: Apr. 15 2008
 

RE: Several things I am curious abou... (in reply to estebanana

Stephen,

Everybody has an opinion and it's a legal, justified demonstration of back talk that makes things move forward. In other words, no one on any chat list can manage certain talk to their liking. It never works with an unchained chat list, with different opinions.

But I agree that we builders are giving our information freely, only it's not us that can demand we be treated with respect unless we find ways to lead with information that creates enough interest to cause valid questions.

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Tom Blackshear Guitar maker
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 25 2018 3:33:54
 
estebanana

 

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RE: Several things I am curious abou... (in reply to Piwin

You should run the Foro and answer everyone's questions then.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 25 2018 4:56:49
 
Piwin

Posts: 2087
Joined: Feb. 9 2016
 

RE: Several things I am curious abou... (in reply to estebanana

I've come a long ways since that day when I didn't realize the saddle was gone (I'm not really interested in building a guitar myself, so I'm talking strictly about my own knowledge of the instrument and how I interact with it as a guitarist). And that's in no small part due to reading through the conversations of all you professional builders on here. So for what it's worth, thanks guys!

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"When I'm dead, I'm going to forget everything – and I advise you to do the same."
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 25 2018 16:47:01
 
Flamingrae

 

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RE: Several things I am curious abou... (in reply to Goldwinghai

Hmmmmm.........Just what was the original question again???
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 27 2018 1:32:20
 
Echi

 

Posts: 513
Joined: Jan. 11 2013
 

RE: Several things I am curious abou... (in reply to Piwin

quote:

It seems to me the moisture absorbed into the wood mostly from the uncoated side. If so, that would cause uneven wood expansion, no?

An answer came out later on, with different strokes: somehow it seems true that the moisture is absorbed more easily from the uncoated side of the wood (as the makers of humidifiers for guitars know well) but conversely some coats of varnish on the inside are not enough to effectively seal the Wood.

Different topic; Some qualified people said that to varnish the inside has a certain effect in the long term wood aging. The thing came out by studying some guitars made by Francisco Simplicio ( who used to do so) and comparing the spruce tops of these guitars with other guitars of the same age.
The Association of the violin makers of Cremona used to publish little booklets for luthiers called “quaderni di liuteria”. In one of them there is an interesting discussion about varnish and wood aging which seems to confirm a positive effect in the long term.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 27 2018 7:16:48
 
Richard Jernigan

Posts: 2501
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: Several things I am curious abou... (in reply to Echi

quote:

ORIGINAL: Echi

Some qualified people said that to varnish the inside has a certain effect in the long term wood aging. The thing came out by studying some guitars made by Francisco Simplicio ( who used to do so) and comparing the spruce tops of these guitars with other guitars of the same age.


What differences did they observe? I would be interested to read more if you might provide a reference.

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 27 2018 7:48:16
 
SEden

 

Posts: 832
Joined: Apr. 12 2008
From: UK

RE: Several things I am curious abou... (in reply to Piwin

I don't know if varnishing the inside of the guitar will be good for it or not.

I do know the fixing a crack or a split on a guitar that has been varnished is a P.I.T.A.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 27 2018 9:12:49
 
estebanana

 

Posts: 7497
Joined: Oct. 16 2009
 

RE: Several things I am curious abou... (in reply to SEden

Be careful Stephen, you know women today are ready to call out ' mansplainin'- take heed of feminists awareness and be vigilant for amateurs' opinions and ' guitarsplaining' .

Since you build for a living you're in their sights.

Be ready to have the not based on experience rebuttal to your opinion go like this- "Well actually the guitar..
..blah blah blah blah.....


Have a nice day everyone.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 27 2018 12:48:26
 
estebanana

 

Posts: 7497
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RE: Several things I am curious abou... (in reply to Piwin

Varnishing the inside will not change the sound I any way that is significant to the playing of flamenco or any other music.

It will not keep a guitar built in high humidity from cracking apart.

Worries about humidity and dryness? Get the best case you can afford that is air tight and keep the atmosphere in the case at an optimum level for guitars. I hear Brune' carries the Visesnut cases. The conversation should be about cases when you're concerns are about humidity.

Can we leave the table now ? We ate all our vegetables.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 28 2018 6:04:39
 
Echi

 

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RE: Several things I am curious abou... (in reply to Piwin

quote:

it will not keep a guitar built in high humidity from cracking apart

For what it’s worth I agree and never said the opposite. My point was that Fleta tried many things to sort this problem out (big problem in his case), and among them he used to varnish the inside. Fleta also layered the upper bout of the top for the same purpose.

@ Richard.
I may provide precise references in a month time, when I will be home. By heart I remember a couple of Cremona booklets about the studies done by Sacconi on the varnishing of the Stradivari violins. In one of them there where plenty if infos about the process of aging of the cells of spruce.
When I mentioned Simplicio I was instead referring to an (amazing) exhibition of guitars made by Simplicio held in Italy many years ago. Few time after that it appeared a nice review in the newspaper “Il Fronimo”.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 28 2018 9:14:12
 
Tom Blackshear

 

Posts: 1794
Joined: Apr. 15 2008
 

RE: Several things I am curious abou... (in reply to Echi

quote:

My point was that Fleta tried many things to sort this problem out (big problem in his case), and among them he used to varnish the inside. Fleta also layered the upper bout of the top for the same purpose.


True science tells us that sealing or partially sealing wood inhibits moisture from going into and coming out of wood, as it happens at a slower rate. I think that Fleta knew this and tried to accommodate certain entry and egress to avoid stress in the wood.

So, this doesn't mean that no cracking would appear in certain climate conditions but that the sealing would slow down the cracking process quite a bit. And building at or near 45% humidity definitely helps.

I think a couple of light coats of shellac is the best barrier for this. It doesn't hinder repair work or cause a cold effect to sound. And it definitely provides protection with slow absorption and release of moisture.

For example: I treat the top inside with a couple of very light coats of shellac before I glue the fan braces. This helps to avoid brace imprints on a thin top, to some extent.

It also helps to keep the wood pores sealed to some extent, which cause the wood chambers to keep from releasing the pectin, a starchy like substance, (due to vibration of the top), which actually allows for a better sensation of sound over a longer period of time.

Violins need to release pectin but guitars should retain it as long as possible. I'm sure you've heard of guitars going soft or flat in their sound over a period of time. Some of this is due to the release of pectin which supports a closed chamber, giving a more live vibration in a guitar top.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 28 2018 14:29:15
 
SEden

 

Posts: 832
Joined: Apr. 12 2008
From: UK

RE: Several things I am curious abou... (in reply to Piwin

I have the chance to wade in a little further today. A 1920 Simplicio just landed on my bench so I just had a quick look at it regarding this subject. It has some finish on the inside of the guitar on the Back and sides. There is no finish on the inside of the top. The are multiple splits in the back and the top. so it hasn't saved it in this case.

Perhaps, by Toms explanation, this is done to prevent the guitar from splitting under brief exposure to extreme low humidity. Still in the long term it hasn't helped

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 28 2018 15:14:26
 
Tom Blackshear

 

Posts: 1794
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RE: Several things I am curious abou... (in reply to SEden

quote:

Perhaps, by Toms explanation, this is done to prevent the guitar from splitting under brief exposure to extreme low humidity. Still in the long term it hasn't helped


I think the obvious reasoning is that we don't leave a valued instrument or any guitar outside by the swimming pool over night, or drop it in the pool to see what happens.

My technique seems to work with building in 45% and following a very light shellac sealing. And to review an old instrument with cracks, first hand appearance, has very little real evidence to secure just what kind of treatment it received over the years.

Years ago, in terms I seem to remember, I read an article that stated shellac was a better sealant than lacquer or varnish.

For example: For about a hundred years, from the 1820s to the 1920s, shellac was the primary finish used (for all coats) by all small shops and factories. In the 1920s shellac was replaced in factories by lacquer for two primary reasons: shellac resin (from bug secretions) is a commodity product that was going up in price as demand increased, while lacquer was going down in price; and lacquer thinner (a blend of solvents) makes lacquer much more versatile in different weather conditions.

Shellac continued to be used by painters and floor finishers working inside buildings and by amateurs until the 1960s. Then three things happened that almost totally ended shellac being thought of as a complete finish:........

Shellac is much more difficult to use (see below) than these three finishes, so it almost disappeared as a finish except in a few niche markets such as French polishing and handmade reproductions of antique furniture............even though this article doesn't address the problem with moisture absorption rates it does address durability.

https://www.woodshopnews.com/columns-blogs/shellac-as-a-sealer-its-all-just-hype

He also goes on to say that Shellac has wonderful blocking properties, better than any other finish. It blocks silicone contamination, which causes fish eye, odors (for example, from smoke or animal urine), and residual wax extremely well.

I think shellac actually has the ability to permeate the wood better, as far as sealing the inner structure of the wood cells, due to its thin quality mixed with alcohol.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 28 2018 16:06:09
 
estebanana

 

Posts: 7497
Joined: Oct. 16 2009
 

RE: Several things I am curious abou... (in reply to Piwin

Shellac is a good stain blocker, and traditional sap and pitch sealer. But not an air blocker.

Shellac is a material that is highly permeable by air at the molecular level. I can dish up the hard science if you all like

This is why anecdotal claim of shellac as a water or air barrier, pardon the pun, holds no water.

Resin oil varnishes are a different fish altogether.

Science says no shellac is not a good barrier. Do I need to break out the science ? Would you even believe it if I did?

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 1:59:34
 
Richard Jernigan

Posts: 2501
Joined: Jan. 20 2004
From: Austin, Texas USA

RE: Several things I am curious abou... (in reply to estebanana

Speaking of science, I googled around for maybe half an hour the other day, and didn't come up with anything immediately applicable to reasonable guitar environments. There were some formulas that could be worked out, but I didn't feel like it would be worthwhile. I did come across a comparison of untreated wood, shellac coated wood and polyurethane coated wood, in conditions that would be extreme for a guitar.

The charts show what happens if you start off with dry wood, untreated or coated, and expose it to 90% relative humidity for more than a month.

The top chart compares uncoated wood with shellacked wood. The x-axis is the number of days of exposure, the vertical axis is the percentage of water in the wood. That is, if you started off with a pound of dry wood, after x days the weight of the water in the wood is y% of one pound.

The different curves are for uncoated wood, the top curve, and for 50 microns, 54 microns and 57 microns of shellac coating. This is roughly one, two or three coats. A pound uncoated wood would end up weighing nearly 1.09 pounds at the end of 36 days.

The second chart is similar, but for polyurethane.


[image] Wood water absorption by rnjernigan, on Flickr[/image]

The data is from

https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-221X2016000300005

which contains some other stuff as well.

Both coatings inhibit water uptake. Polyurethane is better than shellac, especially in the first couple of days, but it's not a very big difference in the long run.

The 50-year old polyurethane on the Ramirez is both thinner and harder than it was when new. I don't know whether or how this would affect the results. I suspect that shellac changes significantly with time as well.

But as I said, this is an extreme environment, soaking at 90% relative humidity for more than a month. The expansion across the grain of a spruce top would be several millimeters.

The wood soaks up a lot of water, but it takes time. Over a day or two, with only 20% change in air relative humidity, the water uptake or loss would be a whole lot less. From the rough numbers I ran, I couldn't arrive at any conclusion one way or the other, whether a coating of shellac or polyurethane would significantly inhibit cracking under normal humidity swings.

Julian Bream eventually had Hauser II replace the back of the famous Romanillos #501, which kept cracking. The guitar was French polished on the outside, but untreated on the inside. He didn't ask Romanillos to do it because Hauser had a better stock of seasoned Brazilian rosewood. If I remember correctly, the original back came for a dining table Romanillos came across at an estate auction. It was hard to get guitar wood in England in the 1970s.

Bream never had any more trouble with the back, but he eventually had Romanillos replace the fan struts on the top, when he felt the guitar was losing some power and tone color after more than 15 years of world travel and hard playing.

Bream traveled a lot. When I picked him up from the airport in Austin for a concert, he had just an ordinary case, not a humidity controlled one. He complained about the swings of humidity, from centrally heated rooms in winter in Sweden to the humid day we met in Austin. I saw the guitar up close that day. It looked like it had been rode hard and put up wet.

My '73 Romanillos, the one just before Bream's, is Indian rosewood. Since 2000 when I bought it, it has lived in a Mark Leaf humidity controlled case, first in an apartment in the Marshall Islands, where the relative humidity often was in the high 50s%, then in Austin where it gets down around 35% in my house in the winter time. It has never cracked. I don't even see a change in the action between winter and summer, but the Mark Leaf case has the best humidity seal of any I have ever owned, judging from how long an Oasis soundhole humidifier lasts in it, compared to Karura and Visesnut cases, which have gaskets that are supposed to seal them.

RNJ

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 4:31:44
 
El Burdo

 

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RE: Several things I am curious abou... (in reply to Richard Jernigan

Very interesting Richard. Data used as info.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 9:27:27
 
Tom Blackshear

 

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RE: Several things I am curious abou... (in reply to estebanana

quote:

This is why anecdotal claim of shellac as a water or air barrier, pardon the pun, holds no water.


I think we all know by now that no finish is going to completely seal wood from moisture.

My reasoning, based on 50 years of experience working with this issue is that shellac is an adequate sealant to inhibit moisture from rapidly filling wood. It's the slow absorption and release rate that protects the wood from cracking, and this ideal comes from a long line of master builders who have tried the process, or subscribe to it.

Years ago I gave a written evaluation for a 1932 Santos classical guitar. The guitar was in perfect condition with an ample finish done inside; a little too much, IMHO.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 10:42:13
 
Flamingrae

 

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RE: Several things I am curious abou... (in reply to Echi

quote:

I may provide precise references in a month time, when I will be home. By heart I remember a couple of Cremona booklets about the studies done by Sacconi on the varnishing of the Stradivari violins. In one of them there where plenty if infos about the process of aging of the cells of spruce.


Another reference for information is the Josef and Reiner Hammerl book "Violin Varnishes" which has a lot more information than the title says. Lots of info on all types of shellac, copal, in fact any resin that you are likely to use including H+S on each. A few recipes for helping to seal "the inside" and other things........
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 13:51:27
 
etta

 

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RE: Several things I am curious abou... (in reply to Piwin

I have a Brazilian flamenco with cedar top which is 10 years old. It is light, loud, clear, and it sounds like a blanca. It is finished inside. I cannot say of course what it would sound like unfinished, and one must be careful with suppositions.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 15:38:29
 
estebanana

 

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RE: Several things I am curious abou... (in reply to Piwin

Ok whatever.. we should call it Hellac instead of shellac.

Shellac, who knew it was so difficult to understand!

I'm super busy with deadlines, but when I get the time I'm gonna go back to school and get an organic chemistry degree and show all you smarty pants guys.

I'll show you! * Raises fist in the air and pumps it *

Why I'll show you!

Come on Checkers, were going back to San Clemente and writing our memoir. They don't need us do they Checkers?

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 15:53:31
 
Richard Jernigan

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Joined: Jan. 20 2004
From: Austin, Texas USA

RE: Several things I am curious abou... (in reply to estebanana

I’m not taking sides in the debate whether guitars ought to be finished on the inside. The only ones I have owned for several years have been unfinished inside. They have survived well, but they have mostly been kept at home in humidity controlled cases.

As I said, the data and formulas I turned up in a brief search didn’t settle the question for me. If I came across a guitar I would like to buy, it would make nearly no difference to me whether it was finished inside or not. The only one I have that is finished inside is loud, colorful and responsive. I’ve only had it for a year.

Which one is best? None of them. My opinion is that once a guitar rises to a certain level of quality, there is no more “better” or “worse”, there’s only “different.” One player may prefer certain qualities, a different player may prefer others.

The only reason I posted the data was to put some numbers into the discussion. Having spent a long career as engineer, physicist and mathematician I have a hard time thinking about questions like this with only qualitative statements to go on.

If I can’t arrive at a decision on my own, and experts disagree, the question remains open for me. Two of the main things a scientific career has taught me are how little I really know, and how many people “know” certain things that are wrong.

RNJ
  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 17:01:09
 
RobJe

 

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jun. 29 2018 17:56:21
 
SEden

 

Posts: 832
Joined: Apr. 12 2008
From: UK

RE: Several things I am curious abou... (in reply to Piwin

So from the graph shown, you can say that using a heavy cut can help the wood against sharp changes but over a prolonged period there is very minimal difference? So it would just be better to build a the correct RH to the environment that is is going into.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 2 2018 9:20:16
 
Goldwinghai

Posts: 106
Joined: Mar. 17 2015
From: Virginia USA

RE: Several things I am curious abou... (in reply to Piwin

I’ve learned a lot from the above posts. Thank you all. One of my guitars has been sitting on the couch for the past three years showing so sign of cracking. According to the hygrometer in the room, the relative humidity varies from approximately 25% to 50%. So now I wonder what extreme ranges of humidity would start causing serious harm to the guitar. For now, this is guitar will continue sitting on the couch, easy for me to grab and play anytime throughput the day. BTW, it’s a low end Camps Primera Negra.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 2 2018 14:00:21
 
Echi

 

Posts: 513
Joined: Jan. 11 2013
 

RE: Several things I am curious abou... (in reply to Piwin

Usually the top is at risk of cracking when it’s very dry.
I live in Ireland and never had problems with the local high moisture in the air.
It also depends how dry were the woods employed and the humidity level at the time of assembling of the instrument.
I know of a maker who write down on the label the relative humidity level of assembly.
  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 2 2018 16:49:04
 
Ricardo

Posts: 10856
Joined: Dec. 14 2004
From: Washington DC

RE: Several things I am curious abou... (in reply to Goldwinghai

quote:

ORIGINAL: Goldwinghai

I’ve learned a lot from the above posts. Thank you all. One of my guitars has been sitting on the couch for the past three years showing so sign of cracking. According to the hygrometer in the room, the relative humidity varies from approximately 25% to 50%. So now I wonder what extreme ranges of humidity would start causing serious harm to the guitar. For now, this is guitar will continue sitting on the couch, easy for me to grab and play anytime throughput the day. BTW, it’s a low end Camps Primera Negra.

As long as you are home and handling the guitar everyday it’s fine.... if you travel make sure to keep it in the case w a little humidity.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 2 2018 18:32:41
 
estebanana

 

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RE: Several things I am curious abou... (in reply to Piwin

I'm just happy Piwin figured out you need a saddle. TGFL

Thank God For Luthiers

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 3 2018 9:20:22
 
Piwin

Posts: 2087
Joined: Feb. 9 2016
 

RE: Several things I am curious abou... (in reply to estebanana

"Need" is such a strong word.
It's those pesky singers and dancers that insist I play with a saddle.

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  REPORT THIS POST AS INAPPROPRIATE |  Date Jul. 3 2018 14:20:34
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