Skin Sagging - How to correct Sagging Skin

[glj]

Two days ago I changed my first skin on my Meinl Conga. I installed a thick cow skin from Moperc.

I followed all instructions for mounting and it looked great when I was done. I noticed yesterday (after +/- 24 hrs of drying) that the skin was "sagging" over the bearing edge of the drum. Needless to say I'm quite dissapointed.

How can I correct this? and also avoid it next time?

Also, if I can't correct it, will it affect the sound or playability of the drum?

[ralph]

soak it again, and re-mount it...i don't know if it will affect the sound much...but its worth giving it a try...

[fed]

Read through the comments on his thread:
http://www.congaplace.com/cgi-bin....84;st=0

Let me know if you have any more questions.

[taikonoatama]

This issue has come up a lot for me when mounting new skins. My guess is that's it's a more common issue in drier climates like we have here in California. I put up a post about it some time back.

As for the cause, it has to do with the top of the skin (exposed to fresh dry air) drying much faster than the bottom, creating a tension differential resulting in the downward warping you're seeing.

Think about it. You got two surfaces, right? Top and bottom. As the top dries it shrinks, creating more tension. Tension looks for a release. If the bottom of the skin is wetter/looser/softer, it's not going to be able to balance/offset the tension from the top, and the result is that it bends in the direction of the release - downwards.

As for why this doesn't always happen with skin remounting, it probably has a lot to do with evaporation rate variables (temperature, humidity, air flow, etc.) from one place to another, a particular skin, and possibly the shape of the bearing edge and drum material. Could be other factors.

I tried different things suggested and have settled (thanks to the advice of "Diceman") on drying the drum upside down on a very flat, hard surface, like a good piece of plywood, covered with a sheet of plastic (garbage bag). I mean you put the garbage bag (smooth out any wrinkles) over the hard surface, then rest the drum upside down on that. This allows the bottom of the skin inside of the drum to get fresh air and better evaporation. You might think this method would cause reverse warping, bowing the skin upward, as the bottom might dry faster. Not an issue - the flat surface keeps things in check.

~james



Edited By taikonoatama on 1199904098

[Congadelica]

The upside down on a plastic bag method is the way to go. it allows the wrapped edge to dry first ans slowly lets the top of the head dry I left is upside down for 2 days then turned it back to let the head fully dry . Also its worth mentioning that you probibly did not have enough tension allowing the the head to sag .

I constanlty check the heads when they are drying evry 4 hours or so for the first few days .

marco

[No.2-1820]

Tension is a big point here, these thick conga skins can quite safely take just enough tension to avoid this happening and like Marco says, stay on it, adjust the tension as the skin drys. I've read many times on the net where 'finger tight' is recommended, in my opinion that not enough and leads to sagging issues, you have to be very careful for sure, but I've had no problems keeping the tension at a level high enough to keep the top nice and flat.


Barrie

[buckoh]

Introducing the newest members of the family:

Sorry, wrong thread!



Edited By buckoh on 1199920029

Attachment: http://mycongaplace.com/forum/eng/uploa ... quinto.JPG

[Thebreeze]

Tension is a big point here, these thick conga skins can quite safely take just enough tension to avoid this happening and like Marco says, stay on it, adjust the tension as the skin drys. I've read many times on the net where 'finger tight' is recommended, in my opinion that not enough and leads to sagging issues, you have to be very careful for sure, but I've had no problems keeping the tension at a level high enough to keep the top nice and flat.


Barrie

This is the way I have always done it and it has always turned out good for me. Not to say that the "upside down" method is not as good or better, I have never tried it but I will keep it in mind next time just for the experience of it.

[blango]

guys,

Its really easy.

when skinning, prep the rim with soap or candle wax lightly.

When drying, slowly tighten the drum and near the end, you can bang lightly on the skin with your fist to make sure the skin is not stuck on the rim - the cause of sagging, or dipping.

take care not to over tighten a wet skin, 1/4 turn on the lugs every 5 hrs or so.

Works every time.

Hope that helps,

Tony

[glj]

Thanks everyone for the tips.

I ended up putting a wet towel over the drum head (while it was still mounted) for approximately 6 hours. I then re-tensioned the skin and put the drum upside down on a garbage bag for 2 days to slow down the drying. I slightly tightened the skin every 8 hours or so; and it seemed to do the trick. The head is now nice and flat and free of any sagging.

It was a time consuming repair as it added another couple of days to my drying time; but I think I will be able to avoid this problem next time.

[TONE74]

I did the opposite. After getting the skin on where I wanted it and got the lugs on evenly I pulled it really tight all around with a pair of pliers making sure I used the same amount of tension then gave the lugs about half a turn ( tighter )with a wrench. After that loosened the lugs 1/4 turn every once in a while while drying keeping the same skin tension through out the drying. After about 3 days it was ready to go.
I din't prep the rim or have anything ready not even a razor. I thought it was an easy procedure. Din't know what I was getting into. It was a bitch getting the skin on. I had to cut the skin with a pair of scissors ( no razor ) but everything came out perfect at the end. I'm not saying this was the correct way of doing it but it worked out for me. Peace

[No.2-1820]

I use a large animal scalpel (wifes a veterinarian!) for the cutting, backed with a thin flexy steel spatula, gets a great neat cut but you must be extra careful with this kind of blade, no room for mistakes !

http://www.amazon.com/dp....ode=asn

Barrie.

[buckoh]

I just removed the existing head on my Ritmo 13.5 to polish all the hardware, and reinstalled it in the exact same position and noticed that , as I tightened it, there was some sagging. I think this is due to the forces applied to the flesh hoop and the bearing edge and is a natural occurance. It has been that way on most conga skins I've mounted that I remember. I never noticed it in bongos.
As far as the scalpel goes, here's an unrelated story. 30 years ago in Wisconsin I was helping my buddies neuter male piglets, 6 weeks old. Russ picked up the piglets by the rear legs and tucked them between his legs, belly out. Stan used a scalpel to slit the scrotum and pop the oysters out. After about 30 of these, one piglet moved too much, the scalpel slipped and cut right through Russ's pants about 1/4 inch from his pair. We named that little piggy KARMA!

[No.2-1820]

I've just reskinned my Matthew Smith's and they turned out great, I used a mule from Isaac for the requinto and a thick steer from Ralph Flores on the tumba, it seems a great combination. I had to adjust upwards the tension on the tumba a number of times to head off sagging and I'm very pleased with the results. It got me thinking about this, a great deal of tension must have been used on the wet skin when they would re head the old tack heads, surely they must have been trying to apply as much tension as possible. Anyone have any knowledge of that process ?

Barrie.

[BMac]

I'm chiming in on two issues.

One issue is this. Is the skin sagging discussed here a problem? I've got that sagging on my only tumba. It has a mid/thick steer hide on it ... I recently mounted. The problem with pulling tension while mounting is that you risk pulling the hardware down and mounting the skin too deeply, depending on your taste. I've got a bad habit of mounting too deep. I finally beat that habit on this tumba. I wanted a shallow mount. I have tone theories about shallow mounts ... I go into all that in other threads. But for this thread, let's just say I wanted to be sure to have a shallow final mount. So I pulled only a little tension and (for a change) waited almost a week while it dried before tuning it. So now it has some sag when it's loose. The sag reduces when I tune it. I don't notice it when I play it. So what's the problem?

Another issue:
I like Barrie's question:
"It got me thinking about this, a great deal of tension must have been used on the wet skin when they would re head the old tack heads, surely they must have been trying to apply as much tension as possible. Anyone have any knowledge of that process ?"

I've got an old conga shell that I'm refinishing. It was a tacked head conga. I removed the old dried-out head. It will soon be time to stretch a new head. I've got a few ideas running around in my head ... but haven't tried anything yet.

Anyone have knowledge on that process?