CONGA MAKEOVERS

[Joseph]

Last photo shows top of shell. You can see where glass cloth is “starved” of resin, and shows up as whitish. This is of no great concern as it is not visible under rim.

Top of shell is uniform in profile, and top surface in “plane”, that is, flat across top of rim.

My questions for the restoration experts, or those who have learned from bitter experience:

1 – After getting over my initial surprise at finding GRP surface, I now like it. It’s probably why this old drum shell hasn’t split or cracked in its life. I’ve read numerous comments on the noted Mahogany (Luan) Gon Bops “dry” sound.
Does GRP have an effect on the sonic properties of a wood shell?
Was GRP lay up on natural finish shells a standard Gon Bops feature?

2 – For a final finish coat over GRP, which has wood surface well sealed, I’m now thinking Carnuba wax, instead of varnish. Carnuba wax would give a more “hand-rubbed” look, and wouldn’t be subject to the scratching / gouging that a top varnish coat would inevitably receive. Any thoughts?

3 – Top rim although “in plane” is very broad, putting a lot of surface area in contact with skin.
Any thoughts on rasping from inside of shell to make staves a bit less thick at top?
What effect would that have on sonic qualities of head?
If it ain't broke don't fix it?

This is not a gold plated refurb, just breathing new life into a classic old beater.
I had thought of using stain effects like those so beautifully displayed on the Matador thread, http://www.mycongaplace.com/forum/eng/viewtopic.php?f=14&t=4170 but after I discovered GRP layer, I wasn't about to sand through that to bare wood....so stain / patina remains the same.
The structural integrity of the shell would I think become less stable if I were to remove that GRP matrix.
After refinish, I’ll just polish original hardware, and mount a mule skin.

Any thoughts, suggestions welcomed.
I’ll send a pic of completed project.

~Joseph

[bongosnotbombs]

Hey Joseph,
The fiberglass coat is absolutely stock, there are certain series of GB's that have it, my friend has one.
Since fiberglass is non-porous I think any coat you put on it will just lie on the surface and easily come off.

I have spent a lot of time with fiberglass from surfing. I think it might be good for you to put a new resin coat on
there. Then you can sand and buff it up, but the drum looks fine without one too.

I think trying to sand and remove the fiberglass coat would be an incredible amount of work, and you would
lose all the structural benefits of having it. I don't think it's a good idea.

I don't know about the sound qualities of having a fiberglass coat, my friends quinto sounded really good with one,
but it just sounded like a quinto, know what I mean?

As far as the bearing edge, it's hard to get it right, if it ain't broke don't fix it. That edge makes for the Gon Bops sound.
My mahogany GB had a really thin edge put on it by a former owner, the soft mahogany was dented all over from playing because
the edge had been thinned and weakened. It took a lot of work to fix it.

You might want to think twice about using the mule on that old drum, the tension mule skin needs puts a lot of stress on the mahogany shells, everyone
I know only uses them on oak, Matt Smith the drum maker told a friend of mine as much as well one time. But maybe the fiberglass makes
the drum strong enough for that.

Very Cool project, good luck with it..

[Chupacabra]

Joseph, nice work on the makeover!
You were wondering if you should alter the bearing edge and wall thickness to alter the sound of the drum. As you said "if it ain't broke don't fix it"...that's right! Altering these features would have a significant impact on the sound of the drum. If you like it already it wouldn't serve any purpose to meddle with it unless you know what the results would be, unless you see obvious flaws such as uneven thickness or other manufacturing defects. It would be a shame to turn a nice sounding drum into something that rings like a church bell or is susceptible to cracking around the edges.
With these shells that have the glass cloth exterior it's difficult or impossible to predict what could happen once the surface is removed. It would be a HELL of a lot of work to get that stuff off! I just learned of this process being used on drums for the first time about a week ago myself and I can't help but wonder - if someone wants fibreglass then just buy a fibreglass drum! For my ears, having a wood shelled drum sounds distinctly different that a fibreglass one; just my $CDN 0.02 worth on that. It's been used for a log time for marine applications for obvious reasons but I just don't get why it would be used on wood constructed musical instruments for anything other that aesthetics. I haven't worked with carnauba wax, other than pressing the "hot carnauba wax" button at the car wash but I hear it's pretty good.

[Joseph]

Gentlemen...thanks for input

The fiberglass coat is absolutely stock, there are certain series of GB's that have it,

Must be the marine grade "Enduro" series.
Interesting that they would have both GRP and naked natural shells.

Since fiberglass is non-porous I think any coat you put on it will just lie on the surface and easily come off.... I think it might be good for you to put a new resin coat on there.

Yes thats what I think was happening on old finish coat: it just had poor adhesion to non porous resin surface. There were several areas where surface varnish just fell off in big flakes.

To make a finish coat stick to non-porous surface, one must rough it up, give it some "tooth", so to speak, so that finish coat has something to grab onto, otherwise the finish coat relies mostly on "film strength": the overall strength of the thin film of varnish (or whatever) encapsulating the shell.

The challenge of of putting on another coat of resin is similar. In boats & surf boards,ideally all resin / fiberglass should be layed up in one process so that in the thickness of the layer(s) is a molecular bond.

Curing one layer (like what I have on shell), then adding on another layer of resin, would depend on a mechanical bond between the two layers (which are 2 separate molecularly cured layers), which relies on having some "tooth" as described above.
I've already wet sanded it baby butt bottom smooth with steel wool / mineral spirits method.
I really don't want to rough it up and risk biting into the glass matrix.
Resin is fairly thick, I don't want thicken coating layers already over wood.
Hence the carnuba wax idea. Easy to apply...just smear it on...then buff. Carnuba dries hard, but is really just a coating of wax over surface, not trying to adhere, or relying on film strength. No heavy build up required. Easy to re-apply

As far as top rim goes, I concur BnB & Chupacabra: If it ain't broke don't fix it!

You might want to think twice about using the mule on that old drum, the tension mule skin needs puts a lot of stress on the mahogany shells, everyone I know only uses them on oak, Matt Smith the drum maker told a friend of mine as much as well one time. But maybe the fiberglass makes the drum strong enough for that.

Interesting observation BnB... I talked with Isaac about that and he said the Gon Bops hardware is not up to mule.
After further discussion it boiled down to: Luan is soft, mule requires tension, lug plate bolt holes thru soft Luan may get larger due to shear load of lug plate bolts under tension. Recommended a thinner skin as a compromise.
I'd be interested in any other thoughts on this subject, before I commit the mule....which I thought would be soon

Again thanks for thoughtful responses
~Joseph

[bongosnotbombs]

I guess if the skin is thin enough it should be okay, if a thinner mule
is going to give you the sound you want, I don't know. Then again a skin can
be changed more easily than fixing shells and hardware.

Yeah I understand now about how you sanded the drum,
doesn't sound like a resin coat is needed at all. I suppose the nice
thing about trying the canuba wax is if you end up not liking it it's easily removable.

You also have the riveted hardware which is the better GB hardware, stronger than
the welded stuff. The GB lugs are not especially strong.

[bongosnotbombs]

Gentlemen...thanks for input

The fiberglass coat is absolutely stock, there are certain series of GB's that have it,

Must be the marine grade "Enduro" series.
Interesting that they would have both GRP and naked natural shells.
[

Well Gon Bops was putting out several lines of drums at different price points; like LP
does today, more or less. They had oak and luan woods, at least three different hardware
styles,finished wood, fiberglass and paint.

The fiberglass with riveted hardware is one of the higher end models.

[Joseph]

You also have the "Voodoo" riveted hardware which is the better GB hardware, stronger than
the welded stuff. The GB lugs are not especially strong.

Ha-Ha!
I am envisoning my eventual eBay ad copy:
'...High end Gon Bops marine grade Mahogany "Enduro" Series conga!
Includes upgraded "VooDoo" riveted hardware to accommodate custom chosen mule skin!'

Seriously though, those lugs are steel! It's hard to believe they would lose the pulling battle with a piece of skin!
I can see holes wallowing out first, or skin ripping.

I want to address other issues of skin / hardware , but don't want to clutter up this thread /subject by going off on a tangent, so I will start another thread, but not now, as I don't have time.

~Joseph

[Joseph]

I guess if the skin is thin enough it should be okay, if a thinner mule
is going to give you the sound you want, I don't know.

That I don't know either.
I just know it's gotta sound better than dried up old skin.
What sound should I want in a drum this size? (conga)
Any suggestions?
Again, that might be fodder for soon to be thread.

~Joseph

[bongosnotbombs]

Seriously though, those lugs are steel! It's hard to believe they would lose the pulling battle with a piece of skin!
I can see holes wallowing out first, or skin ripping.


~Joseph

You'd be surprised, if you go into my Vintage Gon Bops thread you can see the lugs on my
GB with the same hardware as yours were bent all ways, still usable though.

viewtopic.php?f=14&t=3320

I've had to stop placing new skins on drums because the rim was starting to bend and stuff.

btw, I can't remember if that was the Voodoo or International hardware.

[Chupacabra]

The congas that I put together a couple of years ago were done with Moperc hardware that I bought from Michel. Pricey? Yup! Strong? Hell yeah! Worth it?

[SalseroBoricua71]

*

[Joseph]

Thats some serious hardware on that shell Chupa...looks like stainless.
Shell is beautiful also.
I like the "hand tooled' texture of it
What type of wood?
Heavy?

you can see the lugs on my
GB with the same hardware as yours were bent all ways, still usable though.

With all due respect Bongo, those lugs look like a Frankenstein collection.
Frankenstein: functioning entity, assembled from parts of other live and dead entities.

The two lugs on right of picture seem to match, although one is longer.
The other 3 on left side seem to match.
Yes they might have worked to hold down a rim, but would be pulling on it at different angles of attack.
Probably not good for a rim.
All of the bending of them seems to be in area of threads, where a careless wrench wielder could have gotten carried away.
Anecdotal evidence at best.

Another issue best left for other soon to be thread

Regards,
~Joseph

[bongosnotbombs]

With all due respect Bongo, those lugs look like a Frankenstein collection.

Yeah I know I almost didn't reuse them, but they work well enough now with care.
The bends at the threads I think came from bumping against things,
You can see where some of the lugs have been straightened out more than others,
thats from the skin.
The rims on these old GB's are pretty heavy gauge, that kept mine from bending, but the lugs have seen
better days for sure.

[Chupacabra]

Hi Joseph,
That's one thing about these hand carved shells (I have quinto, conga and tumba), they're pretty heavy. The stainless steel hardware adds even more weight but these drums will probably last a long, long time. Even if the shells crack beyond repair, which I doubt they will at this point, the hardware will be useable probably for a few lifetimes. The wood is dugara from West Africa, I'm not sure what region but they were carved in Mali, which is the same wood that some of the djembes are carved from. I like using African cowhide for the skins because of it's rich sound and it's durability.
The next addition I'll be putting on them is some 1/4" rubber cushion around the bottom to protect the floors and edges of the drums.

[vinnieL]

Beautiful drum brother.