Pianotech

Coburn,

I have used both yarn and key bushing cloth. Bolstering can help regain a more circular shape, but does little to nothing for the deep grooves in the working surface of knuckle as you mention. For that, we either resurface with a mini-sanding paddle (with 220 grit wet/dry paper attached) or a svelte, maneuverable electric shaver (thanks to Wayne Ferguson for that!), if you can find one properly dimensioned.

The best remedy for a grooved, deformed knuckle is, of course, replacement. (If knuckles and hammers are of the same vintage and the knuckles are that far down the road, so are the hammers.) One underestimates the importance of knuckle condition at one's own peril.

Alan

------------------------------
Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Alan, what is this svelte electric shaver you mention?

------------------------------
Cobrun Sells
cobrun94@yahoo.com
------------------------------

Original Message:
Sent: 11-06-2021 06:37
From: Alan Eder
Subject: Bolstering Knuckles/Wippen Cushions

Coburn,

I have used both yarn and key bushing cloth. Bolstering can help regain a more circular shape, but does little to nothing for the deep grooves in the working surface of knuckle as you mention. For that, we either resurface with a mini-sanding paddle (with 220 grit wet/dry paper attached) or a svelte, maneuverable electric shaver (thanks to Wayne Ferguson for that!), if you can find one properly dimensioned.

The best remedy for a grooved, deformed knuckle is, of course, replacement. (If knuckles and hammers are of the same vintage and the knuckles are that far down the road, so are the hammers.) One underestimates the importance of knuckle condition at one's own peril.

Alan

------------------------------
Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

If using yarn it absolutely must be 100% Wool.   Anything else will pack down quickly over time.

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

For whip cushions I use .033" (or so) bushing cloth about 1/8" - 3/16" wide. I form the "needle" in the same way I would if bushing a flange, but I harden with CA and then sand it thin so it will sneak more readily under the cloth without deforming it first (like with a big needle). 

Wool yarn is generally my MO on knuckles, though I have occaisionally used cloth (but if they're THAT bad, replacement is probably a better option). 

Peter Grey Piano Doctor

------------------------------
Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
------------------------------

Original Message:
Sent: 11-07-2021 10:55
From: Jon Page
Subject: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Hi Cindy,

The twisting of the yarns actually builds resiliency becasue the shape forces them to bend when compressed.   If all laid flat and straight the fibers aren't bending much at all when compressed.  The major force of wool is that fibers want to straighten out when bent - more than any other fiber known.   For one fiber it's a small force but with many fibers it becomes significant.      Resiliency and cushioning is what reduces noise and compaction over the long run.

Take a sheep to lunch~!    ;-)  David

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583
------------------------------

Original Message:
Sent: 11-09-2021 16:42
From: Lucinda Strehlow
Subject: Bolstering Knuckles/Wippen Cushions

A member of our chapter advocates unwinding the wool yard before you (or as you?) bolster the knuckles. It spreads out, no bumps. She has had great luck with this technique. If you want to know more I might be forced to identify her.

Cindy Strehlow RPT, Central Illinois Chapter

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

But don't take the sheep FOR lunch...😁

Peter Grey Piano Doctor

------------------------------
Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
------------------------------

Original Message:
Sent: 11-09-2021 18:49
From: David Stanwood
Subject: Bolstering Knuckles/Wippen Cushions

Hi Cindy,

The twisting of the yarns actually builds resiliency becasue the shape forces them to bend when compressed.   If all laid flat and straight the fibers aren't bending much at all when compressed.  The major force of wool is that fibers want to straighten out when bent - more than any other fiber known.   For one fiber it's a small force but with many fibers it becomes significant.      Resiliency and cushioning is what reduces noise and compaction over the long run.

Take a sheep to lunch~!    ;-)  David

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583

Original Message:
Sent: 11-09-2021 16:42
From: Lucinda Strehlow
Subject: Bolstering Knuckles/Wippen Cushions

A member of our chapter advocates unwinding the wool yard before you (or as you?) bolster the knuckles. It spreads out, no bumps. She has had great luck with this technique. If you want to know more I might be forced to identify her.

Cindy Strehlow RPT, Central Illinois Chapter

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

What do you mean by "Take a sheep to lunch?"

------------------------------
Cobrun Sells
cobrun94@yahoo.com
------------------------------

Original Message:
Sent: 11-09-2021 18:49
From: David Stanwood
Subject: Bolstering Knuckles/Wippen Cushions

Hi Cindy,

The twisting of the yarns actually builds resiliency becasue the shape forces them to bend when compressed.   If all laid flat and straight the fibers aren't bending much at all when compressed.  The major force of wool is that fibers want to straighten out when bent - more than any other fiber known.   For one fiber it's a small force but with many fibers it becomes significant.      Resiliency and cushioning is what reduces noise and compaction over the long run.

Take a sheep to lunch~!    ;-)  David

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583

Original Message:
Sent: 11-09-2021 16:42
From: Lucinda Strehlow
Subject: Bolstering Knuckles/Wippen Cushions

A member of our chapter advocates unwinding the wool yard before you (or as you?) bolster the knuckles. It spreads out, no bumps. She has had great luck with this technique. If you want to know more I might be forced to identify her.

Cindy Strehlow RPT, Central Illinois Chapter

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

For those experienced "bolsterers" what is your preferred weight of yarn? I have a set I'd like to do, but, looking online, there is a LOT of options. Looking at a chart I see there is 7 different thicknesses from "super fine" to "jumbo". I'm guessing that "medum" or "bulky" may be the way to go. 

For those who bolster, do you generally pull just once through or do more than one? Where do you insert the needle? Directly under the leather or a little deeper in the knuckle?


------------------------------
Ryan Sowers
Olympia WA
360-705-4160
------------------------------

Original Message:
Sent: 11-09-2021 18:49
From: David Stanwood
Subject: Bolstering Knuckles/Wippen Cushions

Hi Cindy,

The twisting of the yarns actually builds resiliency becasue the shape forces them to bend when compressed.   If all laid flat and straight the fibers aren't bending much at all when compressed.  The major force of wool is that fibers want to straighten out when bent - more than any other fiber known.   For one fiber it's a small force but with many fibers it becomes significant.      Resiliency and cushioning is what reduces noise and compaction over the long run.

Take a sheep to lunch~!    ;-)  David

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583

Original Message:
Sent: 11-09-2021 16:42
From: Lucinda Strehlow
Subject: Bolstering Knuckles/Wippen Cushions

A member of our chapter advocates unwinding the wool yard before you (or as you?) bolster the knuckles. It spreads out, no bumps. She has had great luck with this technique. If you want to know more I might be forced to identify her.

Cindy Strehlow RPT, Central Illinois Chapter

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

So many questions: what needle do you use for yarn in knuckle? Or is there a different way you thread the yarn through? Do you pull two rows of yarn through with one insertion of the needle?

------------------------------
Cobrun Sells
cobrun94@yahoo.com
------------------------------

Original Message:
Sent: 11-09-2021 22:57
From: Ryan Sowers
Subject: Bolstering Knuckles/Wippen Cushions

For those experienced "bolsterers" what is your preferred weight of yarn? I have a set I'd like to do, but, looking online, there is a LOT of options. Looking at a chart I see there is 7 different thicknesses from "super fine" to "jumbo". I'm guessing that "medum" or "bulky" may be the way to go.

For those who bolster, do you generally pull just once through or do more than one? Where do you insert the needle? Directly under the leather or a little deeper in the knuckle?


------------------------------
Ryan Sowers
Olympia WA
360-705-4160

Original Message:
Sent: 11-09-2021 18:49
From: David Stanwood
Subject: Bolstering Knuckles/Wippen Cushions

Hi Cindy,

The twisting of the yarns actually builds resiliency becasue the shape forces them to bend when compressed.   If all laid flat and straight the fibers aren't bending much at all when compressed.  The major force of wool is that fibers want to straighten out when bent - more than any other fiber known.   For one fiber it's a small force but with many fibers it becomes significant.      Resiliency and cushioning is what reduces noise and compaction over the long run.

Take a sheep to lunch~!    ;-)  David

------------------------------
David Stanwood
Stanwood Piano Innovations Inc.
West Tisbury MA
508-693-1583

Original Message:
Sent: 11-09-2021 16:42
From: Lucinda Strehlow
Subject: Bolstering Knuckles/Wippen Cushions

A member of our chapter advocates unwinding the wool yard before you (or as you?) bolster the knuckles. It spreads out, no bumps. She has had great luck with this technique. If you want to know more I might be forced to identify her.

Cindy Strehlow RPT, Central Illinois Chapter

Original Message:
Sent: 11/7/2021 10:55:00 AM
From: Jon Page
Subject: RE: Bolstering Knuckles/Wippen Cushions

Bushing cloth for bolstering the wippen cushion. Wool yarn for the knuckles, I've read that you need all wool for the fibers to interlock with the felt. Otherwise, the synthetic stuff can drift out. A blend may be OK?

------------------------------
Regards,

Jon Page
mailto:jonpage@comcast.net
http://www.pianocapecod.com

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

So when does everyone here decide to bolster? On lightly worn knuckles and cushions? Medium worn? Heavily worn?

------------------------------
Cobrun Sells
cobrun94@yahoo.com
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

I am about to demonstrate gang bolstering to my chapter.  When tying to dial in the right amount of material, especially when knuckle deformation is slight, I prefer to use upholstery thread. Three threads through the eye of eye needle yields six strands of thread. Once I have put that much material in the knuckle, I take a look and decide whether or not to do more and how much more I might need to insert. That's just me and how I do it.

------------------------------
Michael Evans
Mansfield TX
817-822-3591
------------------------------

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

I I searched Youtube for bolstering hammer knuckles and found a great little video by my friend and technician extraordinaire, Jim Busby: https://youtu.be/IfZYu5hna2Y

He has very specific recommendations on where to put the yarn - and it is *not* what I would have thought! It's worth watching and I'd be curious to hear other folks comments on this.

 

------------------------------
Ryan Sowers
Olympia WA
360-705-4160
------------------------------

Original Message:
Sent: 11-10-2021 02:28
From: Michael Evans
Subject: Bolstering Knuckles/Wippen Cushions

I am about to demonstrate gang bolstering to my chapter.  When tying to dial in the right amount of material, especially when knuckle deformation is slight, I prefer to use upholstery thread. Three threads through the eye of eye needle yields six strands of thread. Once I have put that much material in the knuckle, I take a look and decide whether or not to do more and how much more I might need to insert. That's just me and how I do it.

------------------------------
Michael Evans
Mansfield TX
817-822-3591

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Ryan,

I agree...I would not (never have thought) of bolstering the distal side. I have always put it in the "business" area. It certainly is something to think about. Hmmm...

Peter Grey Piano Doctor

------------------------------
Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
------------------------------

Original Message:
Sent: 11-11-2021 18:47
From: Ryan Sowers
Subject: Bolstering Knuckles/Wippen Cushions

I I searched Youtube for bolstering hammer knuckles and found a great little video by my friend and technician extraordinaire, Jim Busby: https://youtu.be/IfZYu5hna2Y

He has very specific recommendations on where to put the yarn - and it is *not* what I would have thought! It's worth watching and I'd be curious to hear other folks comments on this.

 

------------------------------
Ryan Sowers
Olympia WA
360-705-4160

Original Message:
Sent: 11-10-2021 02:28
From: Michael Evans
Subject: Bolstering Knuckles/Wippen Cushions

I am about to demonstrate gang bolstering to my chapter.  When tying to dial in the right amount of material, especially when knuckle deformation is slight, I prefer to use upholstery thread. Three threads through the eye of eye needle yields six strands of thread. Once I have put that much material in the knuckle, I take a look and decide whether or not to do more and how much more I might need to insert. That's just me and how I do it.

------------------------------
Michael Evans
Mansfield TX
817-822-3591

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android

Ryan, the video mentions "bolstering on the top changes action geometry." I thought that the compacting of the buckskin/core felt from years of use also changes the action geometry and by bolstering directly underneath the "business" area, as Peter Grey mentions, we return geometry closer to what it would have been when the knuckles and core weren't compacted. Also, I just saw another thread from 2017 on Bolstering Knuckles ( https://my.ptg.org/communities/community-home/digestviewer/viewthread?GroupId=43&MessageKey=d413d575-c668-44d1-8e04-1fcfe523a005&CommunityKey=6265a40b-9fd2-4152-a628-bd7c7d770cbf&tab=digestviewer ) that mentions "The core cloth doesn't wear out, it only compresses with time.  All of the original wool should still be in there!" However, wouldn't it also be true that if something has been compressed, it will have a "memory" of that impression and will quickly resort back to that memorized compaction? Thus why I'm in favor of bolstering, needling, and squeezing the knuckles rather than needling or squeezing knuckles alone without bolstering.

------------------------------
Cobrun Sells
cobrun94@yahoo.com
------------------------------

Original Message:
Sent: 11-11-2021 18:47
From: Ryan Sowers
Subject: Bolstering Knuckles/Wippen Cushions

I I searched Youtube for bolstering hammer knuckles and found a great little video by my friend and technician extraordinaire, Jim Busby: https://youtu.be/IfZYu5hna2Y

He has very specific recommendations on where to put the yarn - and it is *not* what I would have thought! It's worth watching and I'd be curious to hear other folks comments on this.

 

------------------------------
Ryan Sowers
Olympia WA
360-705-4160

Original Message:
Sent: 11-10-2021 02:28
From: Michael Evans
Subject: Bolstering Knuckles/Wippen Cushions

I am about to demonstrate gang bolstering to my chapter.  When tying to dial in the right amount of material, especially when knuckle deformation is slight, I prefer to use upholstery thread. Three threads through the eye of eye needle yields six strands of thread. Once I have put that much material in the knuckle, I take a look and decide whether or not to do more and how much more I might need to insert. That's just me and how I do it.

------------------------------
Michael Evans
Mansfield TX
817-822-3591

Original Message:
Sent: 11-06-2021 01:12
From: Cobrun Sells
Subject: Bolstering Knuckles/Wippen Cushions

Just seeing a recent thead mentioning bolstering I thought I'd ask as well.

What is everyone's bolstering policy? Do you? Do you never? When do you? How do you? With yarn? Key bushing strip? How do you thread through? Tell ALL your secrets. I want to start doing so on deeply grooved knuckles.

Sent from Yahoo Mail on Android