Finishing the insides of shells

Larry

"Uncle Larry"
It doesn't seem like the insides of drum shells gets much attention. I think it's a safe statement to say that finishing/not finishing the insides of a shell has a marked effect on the total resolved sound. I think you can "fine tune" the ringy characteristics of a drum by treating the insides. Perhaps, just for debates sake, that a "totally finished on the inside of the shell" treatment would be too ringy, and a "totally unfinished on the inside of the shell" is not ringy enough. Then one could put in alternating "stripes" of finish to arrive at the desired amount of ring from a drum, if desired.

Also, is lacquer harder than polyurethane? How about paint like Gretsch silver sealer or the white Benjamin Moore paint Ludwig used on their 60's drums. My first guess is I would think paint like that isn't all that hard compared to poly or lacquer, but I don't really know.

It just seems to me that there a number of different ways to treat the insides to arrive at a desired sonic goal. I mean you could even rough the insides up to lessen the ring if so desired. Instead of muffling, maybe that's another way to get rid of excessive ovetones, for those who prefer that sound.

I polyurethaned the insides of a very cheap snare drum recently, and it added much more ring, which was the reason I did it. I felt the drum was too dead before treatment. I liked the improvement, it gave the drum different sonic characteristics.

I think there are other threads dealing with this but I wanted to start a new one to get fresh opinions. How many have treated the insides of their shells?
 
Larry, put simply, finishing the inside of the shell is far more important than finishing the outside. Of course, the outside is what everyone concentrates on. After all, 90% of drummers buy with their eyes.

"Finishing" is a broad church. To some manufacturers it's adding a coating to mask inferior timber or seal the wood to prevent ingression of moisture. To others it's a point of pride to pay as much attention to the inside as they do the outside, but in very few cases is there a priority placed on sonic augmentation. Of course, there's some that have put such a marketing spin on something with much more humble initial purpose, but we'll leave that for another day.

I think it's necessary to provide some clarity to the affect a finish can have, as I've noticed some are concerned about adversely affecting shell resonance. The affect on shell resonance is directly proportional to the change of mass & additional stiffness that an internal coating can bring to the party. For example, a very thin coat of lacquer will have minimal affect, but a thick coating consisting of multiple layers will affect resonance, although with associated stiffness increase, not always adversely. I hate to keep cracking the same old nut, but internal finish is just another element that must be considered in the context of the whole design, not in isolation.

As a general guide, if you have to rely on applying an internal finish to fundamentally shape the drum's sound, you've already got it badly wrong, at least, aligned with your expectations of the instrument.

Some examples of valid approaches:

If you have a drum made of a softer wood species, & you want to brighten it, then lacquering the inside with a fairly thick coating will do the job, but it will also stiffen the shell. Depending on other factors, it's likely to slightly raise the fundamental too, & also stifle lower frequencies. Counter intuitively, it's also likely to lengthen the note of the drum.

If you have a drum made of a harder wood species, applying the lacquer as in the soft wood example is also likely to brighten the drum, but less obviously so. It's unlikely to raise the pitch, but it is likely to shorten the note. In this example, if all you wanted to do was brighten the drum slightly, then hand finishing the inside of the shell to a high standard, then finishing with a very thin lacquer coat, would be the most appropriate action. In some cases, just high quality hand finishing will yield a good result, especially when aligned with a high quality wax & a good buff.

To sum up, to decide the most appropriate course of action, you need to evaluate what you currently have, decide what you want to achieve, then plan a course of action having carefully considered the downsides as well as any potential benefits.

This is a very big subject, & there's lots more to it than I have time to put up here. Mr.s Simple has prepared a superb curry, it's ready to serve, & I'm getting "the look".
 
That's really too much to buy without some evidence. Show me the test results where you lacquered lumber and measured its "stiffness." Show me the double-blind tests describing the tone of a drum. Or better, if we can have spectral analysis cymbal reviews, why not the same for drum finishes?
 
It's funny, I've done the exact opposite. I sanded the inside Laqour out of a drum before to help get rid of its overly ringy overtones. It worked excellent. It's funny though, some people here thought I was lacking intelligence when I was considering performing the same task on a more expensive drum. I've also laquored the inside of a floor Tom to give it a bit more life. And it worked flawlessly. People paint the inside of shells all the time, and a lot of older drums came with painted finishes on the inside. I believe that modifying the inside of the shell can be very affective for achieving the desired results in the sound on which a person is trying to achieve out of the specific drum(s).
 
Thanks Andy for that great info. Most inside shell treatments that you hear about are DIY. What major advertises what they do inside the shell, other than Gretsch? None spring to mind. There's room for a LOT of tonal variations. Andy mentioned stiffness. I hadn't considered that. Is that a desirable thing? I can hear Andy say...it's part of a whole...nothing in isolation...blah blah...and I totally agree, but what does stiffness do?

I wish there were a standard of some sort. Like for ring... which finishes occupy the high end of the spectrum, which finishes occupy the low end. What else can you get besides ring and no ring? buzzes? A buzzing tom? That might sound interesting. What would sound absorbing finishes do to the tone? What would motorized pinwheels inside the drum do? Would they make a Leslie type sound from my drums?

I think there are many possibilities to alter a drums tone that have yet to be exploited it seems.
 
Another process that I used to hear about was Vibrafiying drum shells. Basically the shells were lined with a thin layer of fiberglass.
 
interesting thoughts larry, i always thought my pearls had some kind of finish inside, they smell like it when i take the heads off. My luddies have the granitone so they are finished inside without a doubt. im sure through a lot of R&d andy went through this and picked the best process for his specific shells.he probably uses a wind chime to test the timber of the shell to but thats another thread.
 
I built my own natural maple snare, 5x14, and sanded the inside lightly, sprayed with a coat of deft sanding sealer, and re-sanded lightly. it gives a nice moisture barrier for protection, and warms up the look. It is not thick enough to really "stiffen". but, the drum has a nice warm balanced sound.
 
That's really too much to buy without some evidence. Show me the test results where you lacquered lumber and measured its "stiffness." Show me the double-blind tests describing the tone of a drum. Or better, if we can have spectral analysis cymbal reviews, why not the same for drum finishes?
It makes sense to me, Soupy. I don't see a reason for Andy to embellish physics.
I have no issue describing both our work & the rationale behind the statements. It's fine for Soupy to be quizzical. I certainly don't believe sweeping statements, & often ask for further detail.

Soupy, we don't have spectral analysis results, nor do we have fully documented tests C/W control samples. We have neither the technical nor time resources at our disposal, but we have done the testing, & our ears are the instrumentation. We haven't tested every possible variable, but we have tested the extremes, then used existing knowledge to fill in the gaps. I'm not saying our work is definitive, nor is it exhaustive, but it's a damn sight more than most have worked through. Canopus have done some great work on external finishes. Probably one of the few that have. Their work on stiffness imparted by various finishes concurs with ours on internal finishes. On the balance of evidence to date, coupled with our general knowledge of the affects of stiffness, mass, & surface finish augmentation, I'd say we have a fairly clear picture of the implications associated with this subject.

TBH, even if we did have detailed results, we'd be most unlikely to release them on a public forum so other much more ably financed companies could ride on the back of our work. We already impart a lot of information here in the spirit of assisting others. Much of that information has nothing to do with our business, & certainly won't benefit us directly, so I think we give enough - probably too much already. I don't see any other drum companies coming on here to help members by applying their knowledge to the challenges faced by others.

It's funny, I've done the exact opposite. I sanded the inside Laqour out of a drum before to help get rid of its overly ringy overtones. It worked excellent. It's funny though, some people here thought I was lacking intelligence when I was considering performing the same task on a more expensive drum. I've also laquored the inside of a floor Tom to give it a bit more life. And it worked flawlessly. People paint the inside of shells all the time, and a lot of older drums came with painted finishes on the inside. I believe that modifying the inside of the shell can be very affective for achieving the desired results in the sound on which a person is trying to achieve out of the specific drum(s).
All good stuff. There's two distinct areas of interest here. Designing drums from the ground up, c/w internal finish considerations. That's what drum manufacturers do/should do. Then there's the customer customisation angle. Taking a drum you already have, & augmenting the internal finish to "fine tune" certain aspects of the sound. Really, outside of major reworking, the affects you can expect from doing so yourself are more tonal than characteristic changing. Brightening or darkening the tone, especially applied to tones after the initial voice, are well up for experimentation.

Andy mentioned stiffness. I hadn't considered that. Is that a desirable thing? I can hear Andy say...it's part of a whole...nothing in isolation...blah blah...and I totally agree, but what does stiffness do?
Yes, sorry Larry, but the blah blah blah is important, & that's why I mention it so much. Stiffness. It's not rocket science. If you have a thin shell made from a softer wood, then applying multiple layers of lacquer will add both mass & stiffness to the shell. Mass is an obvious one, because you're adding something. Stiffness is because layers of lacquer are stiffer than the soft wood, & adding thickness automatically adds stiffness, all other things being equal. Stiffness brings many things to the party in drum shell characteristics. Not least of all, typically brightness & volume, but also changes to the resonance properties of the shell. There's a million + one caveats to that, & too numerous to go into here, but it's a factor to consider if contemplating adding an appreciable number of lacquer layers to the inside of a shell, or indeed, lining with fiberglass.

Another process that I used to hear about was Vibrafiying drum shells. Basically the shells were lined with a thin layer of fiberglass.
i know of it, but I'm not a fan. That does't mean to say it's not a valid choice, it's just I'd rather rely on other constructional consideration to produce the desired sound.
 
mmm... I do love a good curry.

I had a my Stage Customs finished with Tung Oil on the inside when I had them wrapped. Between the new edges, the finished interior and the shortened bass drum I could hear difference but I'm not sure that I could attribute that to one thing.

As mentioned on THIS poor neglected thread, I want to finish the interior of these new Drumcraft toms I bought. What would some sanding and a layer of oil do to the sound of a birch drum? is there any preferable alternative to tung oil?

I also want to put Larry's experiment of polying the inside of a cheap drum to try and liven it up to the test.
 
What would some sanding and a layer of oil do to the sound of a birch drum? is there any preferable alternative to tung oil?
Tung oil, teak oil, all offer protection, but do little to change the surface finish (apart from possibly slightly raising the grain on first application). We use an oil that hardens. It not only feeds the wood, it also leaves a micro thin hard protective layer. Very expensive :(

As for the affect on a birch drum, that rather depends on the existing surface finish. If it's already smooth, then sanding & adding a proprietary oil won't alter the sound much. If the existing finish is poor, then it might brighten it up slightly. Difficult to say really without understanding the other constructional factors.
 
We already impart a lot of information here in the spirit of assisting others. Much of that information has nothing to do with our business, & certainly won't benefit us directly, so I think we give enough - probably too much already. I don't see any other drum companies coming on here to help members by applying their knowledge to the challenges faced by others.

... and you hit the nail with that remark Andy, I for one is delighted for you sharing your skills and experience as drum manufacturer and engineer, and I'd have to say that reading your technical posts is both a rewarding, enlightening and positive experience, you're right, no other companies individual chime in with such an inside, such a knowledge and worthwhile advice as you are Andy, we are ever so grateful to have someone with this kind of knowledge who is willing to share it among us, and I'm not the only one appreciating this kind of imput from you here at DW, that's for sure.

Sorry for the derail Uncle Larry, but I thought it was worthy of highlighting to have such knowledge and information at hands :)

On the topic of this thread, I can report that my Tama Artstar II is laquered both inside and out with no gloss finish on the inside, the inner shells (maple) are extremely smooth, and Tama at the time claimed the process as "creating an acoustically perfect resonance chamber within the drum itself", I have to admit that I've never had to complaint about how my drums sounded at the exception of my poor tuning skills, lol, the shells are not at fault, I am!!!
 
Yea, we really are lucky to have Andy here. Try and imagine this place without him...*shudders* *cold chill*...It's nice to appreciate someone while they're here.

Andy, on behalf of everyone here, I think it's safe to say that your input here is pure gold. Especially for the drum builder geeks and wannabes like me. The info you dispense here...it's so generous. Thank you.
 
I remember previously coming across this description on the DW Drums website regarding their Collector's Series snares:

A lacquered interior adds brightness to a snare with a full tonal spectrum and plenty of body.

IMO, a previous maple Collector's Series snare I had did not exhibit much brightness.
 
It's fine for Soupy to be quizzical. I certainly don't believe sweeping statements, & often ask for further detail.
Absolutely, please consider me well-intentioned.

TBH, even if we did have detailed results, we'd be most unlikely to release them on a public forum so other much more ably financed companies could ride on the back of our work.
I'll agree with you, there's a difficult line between describing your products well enough to convince the world that they're different, vs openly catering to copycats. Of course, more ably financed companies could just as easily and thoroughly perform their own testing and research. As an example, Pearl certainly looks like they were willing to perform testing in shell forumation and bearing edges for the design of the Reference series.

We already impart a lot of information here in the spirit of assisting others. Much of that information has nothing to do with our business, & certainly won't benefit us directly, so I think we give enough - probably too much already. I don't see any other drum companies coming on here to help members by applying their knowledge to the challenges faced by others.
The flip side is that you've created a successful quasi-grassroots marketing machine in this forum, with people who've never even seen nor played your product. It is a mutually beneficial relationship, and it is built upon the way you participate in the forum. And to be fair, there are other forums which discuss building far more detail that Drummerworld.

It makes sense to me, Soupy. I don't see a reason for Andy to embellish physics.
Herein lies the rub. No science, and no physics have been presented. I don't doubt that the craftsman at Guru are highly skilled artisans. But without published data to back up their observations, there is no science. That's what science means: To create a hypothesis, test it, and then publish the results so that they may be validated by their peers. Why? Because sometimes scientists are wrong.

I guess what makes me grumpy comes down to a combination of semantics and ethics. Even when we're talking about anything as cosmically unimportant as how to build a drum, I don't believe it is proper to confuse experience with science, to confuse anecdote with fact. You may dismiss me for getting worked up about semantics, but there's a big difference between saying "Lacquer makes drum shells stiffer and changes in the sound! FACT! PHYSICS! SCIENCE!", as opposed to saying, "In our experience as craftsman, we have found that lacquered shells have slightly different characteristics than unlacquered. You may perform your own tests and develop your own conclusions." It is unethical to use a veil of pseudoscience to present information which has not been vigorously validated as fact.

And let me be clear, I have no doubt that Andy has done the testing he says, and have no doubt that he is confident in his results, and that he is sharing his experience with full honesty. The artisans at Guru appear to be top-notch at their trade. But that doesn't mean we can confuse an artist with a scientist. There's a lot of complete bullshit in the world posing as science. And that does a disservice to real science.

Sorry, end of rant. To go back to some nuts & bolts:

Stiffness. It's not rocket science. If you have a thin shell made from a softer wood, then applying multiple layers of lacquer will add both mass & stiffness to the shell. Mass is an obvious one, because you're adding something. Stiffness is because layers of lacquer are stiffer than the soft wood, & adding thickness automatically adds stiffness, all other things being equal.
A lacquer finish might be what, 10 mil or less thick? That's less than 3/256th of an inch. Compared to a shell that's 1/4" thick? I would suggest that the effect on stiffness and mass would be relatively negligible. If I can get off my fat arse, I should perform my own tests and report my results. But I guess until I do, my conjecture has no real value.
 
Absolutely, please consider me well-intentioned.
I do, & welcome scrutiny that comes from a positive & open standpoint.

I'll agree with you, there's a difficult line between describing your products well enough to convince the world that they're different, vs openly catering to copycats. Of course, more ably financed companies could just as easily and thoroughly perform their own testing and research.
I think we generally step well over that line. Partially through enthusiastic ignorance, & partly through desire to inform.

The flip side is that you've created a successful quasi-grassroots marketing machine in this forum, with people who've never even seen nor played your product. It is a mutually beneficial relationship, and it is built upon the way you participate in the forum. And to be fair, there are other forums which discuss building far more detail that Drummerworld.
I was an active contributing member here for some considerable time before I hooked up with Dean. When we started to develop principals of construction together, I fed some of that information into the forum. There was a strong interest in what we were doing, I think mainly because we were taking an obviously different path. There continues to be a strong interest. Many have told me privately that they find what we're doing to be fascinating, & enjoy sharing the journey. My primary objective is to participate, & if members become enthusiastic about what we're doing, then that's cool. Your use of the word "created" implies that the current situation is by design rather than evolution. I can assure you it's not. By far the greater portion of my posts here are nothing to do with our business. I put up my playing (FWIW), & regularly contribute to a host of threads completely devoid of drum business interest. I also regularly comment positively regarding all types, makes, & forms of drums by others, & try to help out with construction issues in a non partisan way. More often than not, it's others who raise Guru, not me.

You may not know this, but I feed very little Guru activity into this forum. I certainly keep commercial stuff right out of the way, despite requests to do so by DW forum members on other platforms. I only post stuff here that I genuinely believe is informative. The possible exception to that being magazine reviews, but TBH, I'm just so pleased about the reviews personally, that I feel inclined to share my good news, just like any other forum member here. I do put up things here that represent new thinking. Stuff that just hasn't been done before, as I believe that to be of strong interest to the forum. I do sometimes ask the membership for advice & opinion. Yes, we really get something from that. Those opinions are valuable to us, & in that regard, I admit using the forum as a resource. That said, members seem happy to help out. The moment I felt I was leaching of the forum in any regard, I'd walk away. Similarly, the moment I feel my presence is resented, I'll do the same. I completely concur on one point, balancing being Andy the forum member with Andy the drum company partner is a tough act. I'm not saying for one minute that I always get the balance right.

Herein lies the rub. No science, and no physics have been presented. I don't doubt that the craftsman at Guru are highly skilled artisans. But without published data to back up their observations, there is no science. That's what science means: To create a hypothesis, test it, and then publish the results so that they may be validated by their peers. Why? Because sometimes scientists are wrong.
Agreed, but we'd never be in a position to publish such data for scrutiny by our peers. We don't have the vast sums of money necessary to patent every aspect of our designs, & without that protection, publishing all your R&D findings is just giving away your hard work for the benefit of others.

And let me be clear, I have no doubt that Andy has done the testing he says, and have no doubt that he is confident in his results, and that he is sharing his experience with full honesty. The artisans at Guru appear to be top-notch at their trade. But that doesn't mean we can confuse an artist with a scientist.
Thank you for the positive context, but I've never presented anything here as science, veiled or otherwise. I've often stated that we do our own research, so clearly anything we say regarding drum constructions is most likely based on our experiences. There shouldn't be the need to clarify & highlight that every time I make an observation.

A lacquer finish might be what, 10 mil or less thick? That's less than 3/256th of an inch. Compared to a shell that's 1/4" thick? I would suggest that the effect on stiffness and mass would be relatively negligible.
The lacquer treatment I'm referring to is more akin to thicknesses used for external finishes. Those lacquer coatings can be upwards of 1mm thick, so on a 6mm thick shell, it's an appreciable portion of the shell structure.


Soupy, thank you for your candor, I appreciate it.
 
Yea, we really are lucky to have Andy here. Try and imagine this place without him...*shudders* *cold chill*...It's nice to appreciate someone while they're here.

Andy, on behalf of everyone here, I think it's safe to say that your input here is pure gold. Especially for the drum builder geeks and wannabes like me. The info you dispense here...it's so generous. Thank you.



+1000.I agree 100% Larry.Andy gives very generously of his time and extensive knowledge concerning all that is drum building.

Aside from Ludwig,Slingerland,Rogers,Camco,Hayman and Gretsch who did finish the inside of their shells at one time on another,Tama was a big proponent of doing that at one time also.From Zola coat to same color stain interior and exterior finishing.

I believe Tama is returning to this concept with their new Star line of drums.Their interior is stained the same color as the exterior finish.

My 77 Superstars are also stained on both the interior and exterior.

Thanks again Andy, for the input,humor and generous sharing of your extensive knowledge.This forum would indeed NOT be the same without your presence.Cheers.

Steve B
 
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The flip side is that you've created a successful quasi-grassroots marketing machine in this forum, with people who've never even seen nor played your product. It is a mutually beneficial relationship, and it is built upon the way you participate in the forum. And to be fair, there are other forums which discuss building far more detail that Drummerworld.

I honestly think you're holding the wrong side of the stick here Soupy, and trust me, I'm not saying this because I'm openly friendly with Andy within this forum, if I felt the same way you did regarding your grassroots marketing assumption, I would be more than happy to agree with you, but it's genuinely not case.

Andy is an extremely popular member on the forum, even if you take the Guru topic and the knowledge aside, Andy's participation and input is very broad, and he participate actively within the daily life and events on the forum, he's an avid fan of the "Your Playing" section and comment almost daily upon the threads other members upload in this particular section.

Andy helped me on several occasions too, mostly secretly via PM, without me asking for anything in the first place, just to put a picture of the kind of man Andy is, a genuinely warm hearted and generous guy by nature.

Many of the much needed technical explanations Andy dare sharing with us here are totally denuded to any link or association with Guru drums and their solely purposes is to help those (like me) to understand the topic being discussed, no more no less.

But Andy (and Dean) is also the man behind Guru drums, and it is "normal" that he talks about it, present pictures before the forum and share his enjoyment when Guru receive a positive magazine review, the enthusiasm for Guru from many members here are not the fruit of plans made out by Andy, it's simply a recognition and an admiration for the product, the dedication involved and the craftsmanship.

As for the other comment you've made, I'm happy to say that I've seen, played and tested the new Guru Origin Serie last year. It's so good that if eventually I replace my current kit, it will be a Guru Origin Classic kit, and I've made that decision based upon my judgement, not on what Andy or whoever said about their product.

In resume, Andy is a well-intentioned member who's just enjoying the forum and happy to help other members, just like you or me would do within what we can offer.

There's no grassroots marketing machine in this forum.
 
Thanks Henri & Steve, but I'm completely cool with opinions expressed here. Points are made, & explanations given in return. I value your points of view & support, but I also value Soupy's points of view too. In fact, this is a perfect example of how differing perspectives can be discussed without malice or agenda. Nothing is absolute, it never is, & that mirrors how we perceive changes to drum sounds through augmentation of any kind. So in a funny sort of twist, this sidetrack brings us back to the topic in hand.
 
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