Hands Free Bellows Testing

[Terry McGee]

Nothing in the village in the way of "shoe cream" per se. But I did find some Waproo Zorbel Leather Conditioner, described as "a superior leather conditioner with a rich blend of natural waxes and Lanolin. Protects, cleans, polishes and preserves smooth leather. Waxes sounds like a good word, but lanolin is a grease, so might cause subsequent gluing issues. But let's see.

 

In the meantime, I've also come up with a new test. I made up a prick, using a short length of guitar top string set into a plastic handle. With this I can introduce leakage in otherwise good leather. (Sounds like those people who develop new viruses for military purposes, doesn't it! Imagine how popular I could be at a concertina convention!) The prick diameter is 0.33mm, but I imagine the holes it makes are much smaller.

 

Here's a record of its first outing:

 

I used the piece of leather I'd coated with KLIWS. You'll remember it started off with 0.275LPM leakage, but with the application of the KLIWS, that dropped to zero (or at least <0.05LPM).

One punch of the prick brought the leakage up to 0.1LPM, but subsequent punches produced varying results, probably because leather is not homogeneous.

Five punches brought it up to 0.2LPM

Another application of KLIWS reduced the leakage to zero again (or at least <0.05LPM).

 

So we can now fix leaky animals, make them bad and fix them again. That's starting to sound like the basis of a methodology.

 

Time to go try out the leather conditioner.

 

Terry

[Terry McGee]

OK, next exciting episode....

 

I've now made six samples, tested them fresh, treated them with various substances, pricked them to make them leak again and retreated them to prove we can.

 

But we have to be able to answer the question - can we glue a patch to this stuff later if needed? And will this patch leak? And come off too easily? So, to start answering those questions, I've added another harsh and unnatural punishment. Each sample has a 3mm (1/8") hole punched out of the middle. No need to test the leakage of that - it will be disastrous. And then an 8mm (5/16") leather disc glued over it, using PVA. Once the glue dries, we test again, but this time, with the patch on the other side from the pressure. Easier to blow a patch off from behind than in front.

 

 

As you can see, the Dubbin and the Zorbel drew the worst leather samples, but I left them in, as they seem to be able to deal with it. Indeed the second column indicates that all the treatments pretty much annihilate leakage. Only the plain old shoe polish had any leakage left, and I think that's probably a statement that the cake polish is harder to apply.

 

Edited to throw in some new samples - a "control", which will illustrate what happens with no treatment, and PVA glue. One of the good things about modelling is no concertinas need to be hurt in the conduct of this experiment. The control should be useful when we come to testing stickability.

 

When we come to the five pricks test, we again see that the Dubbin and Zorbel suffer most. I don't know if that is coincidence, but it's probably not important. In the Re-treated column, we see the new holes can all be fixed by all the treatments.

 

Finally, the punched and patch column indicates the leakage that remains after the 8mm patch is glued over the 3mm hole. All show a little leakage, which is interesting. I'd be confident that another dose of the relevant treatment will fix any remaining leakage. Note that the Control (which so far had escaped treatment) has improved dramatically in the Punch & Patch test. This is first because the 5 pricks have been patched, which should return it to original condition, around 0.3LPM. Further, it now has an 8mm patch glued in the middle of the 11.3mm diameter test area. So about 50% of the area has essentially become treated with PVA. One half of 0.3LPM is 0.15LPM, exactly what we got. Ain't science wonderful!

 

I think the real question is how well do the patches stand up to rough treatment? To be fair, I should leave them a day for the glue to settle down.

 

Terry

Edited July 11, 2014 by Terry McGee

[Rod]

Terry, I wonder if this will all culminate in you deciding that in this day and age leather is no longer the most appropriate material from which to construct Concertina bellows. ? Perish the thought ( pun intended ) !

[Terry McGee]

Curse you, Rod, for exposing my plans for world domination! But too late! McGee's Patented Impregnated Kevlar Bellows will sweep all resistance aside!

 

It is remarkable that after so much development in material science over the past century, we are still so reliant upon cutting down trees and hollowing out marsupials. But it is hard to get excited over plastics! I make polymer flutes, but I won't say I enjoy it to anything like the extent of making wooden flutes. Even though they are probably slightly more efficient.

 

Terry

[Rod]

Terry, I believe that the first false teeth were made of wood but that they eventually hit upon a material that was rather more appropriate. I rest my case !

[Terry McGee]

Many a true word spoken through false teeth.

 

I guess it's possible that a close examination of the weaknesses of traditional materials might prompt us to think of better modern replacements. It's hard to imagine getting excited about a concertina with 3D printed poly ends and vinyl bellows!

 

Terry

[Terry McGee]

Hmmm, another day and another experiment. We'd got to the point above where I'd punched 3mm holes in all the samples, and used PVA to glue 8mm discs over the holes. They've had the best part of a day to dry. The question I now faced is how to test the patches for adhesion. You'll remember some of the treatments, eg Dubbin, were likely to make the leather hard to glue to. I had several thoughts in mind:

• rig up an arrangement that supports the sample, attach a thread to the patch, and load weights on the end of the thread until it pulls away.
• apply loads of air pressure to the back of the sample until it blows the patch off, or
• just form a subjective view of how well the disc is attached.

To some extent, matters were taken out of my hands. I gently pulled on the Dubbin treated sample, and the patch came away easily. A little despondent, I pulled on the others, and the same thing happened - none of them seemed to be well adhered. When this included the "control" - the sample without treatment, I started to wonder if PVA was really a suitable glue for leather. (Yes, I know everyone seems to use it!) A more likely variant of that thought is that probably I had starved the joint. I was certainly trying not to overload the joint with glue, and perhaps I went too far.

 

Only one sample left now, the one treated with PVA. Hmmm, it seems very well adhered. So, maybe I'll try the overpressure approach and see what that tells us.

 

I put the sample back in the holder, clamped all round with heavy clamps. And attached it not to the hyper-sensitive measuring equipment as usual, but to the output of the pressure regulator, fed by the workshop compressed air supply. This wasn't the time to play nice. I did include the least sensitive (20LPM) flow meter so I could see when it was starting to leak.

 

I started winding up the pressure, monitoring the pressure and flow. It got up to an extraordinary 60psi - that's 42,000mm of water - before it finally let go. The other tests were conducted at 250mm. And the disc didn't blow off, just lifted off one side. And the whole test area of 11.3mm diameter was distended like a nipple. So the glue definitely worked there!

 

I think the big difference here was twofold. Firstly, the PVA doped leather provided the perfect surface to glue to, whereas all the other treatments, or even no treatment at all were less good to glue to. Secondly, glue starvation was not so much an issue, as one of the surfaces was already "sized". I think I need to revisit the other surfaces to see if they can be made glueable.

 

Terry

[Rod]

Terry, Were you perhaps a trifle hasty in your enthusiasm. Perhaps the various samples should have been allowed more time to mature before you subjected them to testing. Did you clamp them in any way so that they were drying under pressure. Whatever the outcome you will go down in history as the patron saint of leaking bellows !

[Terry McGee]

It's a fair cop, m'Lud. Actually intentionally a bit hasty. I thought through the question "how long should we wait before proceeding?", and of course, it's unanswerable. Not knowing what they comprise of, we don't know how long these treatments take to "dry" or indeed if they will "dry" at all. And even if we knew, it probably wouldn't be a case of them suddenly snapping dry on day 3, but more like a half-life situation - half dry on day 3, 3/4 dry on day 6, 7/8 dry on day 12, etc. Against that, we couldn't be sure that at least some of them wouldn't impede the glueing action even when freshly applied. I figured, for example, that the KLIWS must be waterbased, as the instructions say to rinse out the sponge applicator under running water after use. So the base shouldn't interfere with the base of the PVA, which is also water. (I suspect the same can't be said of the waxy material probably held in aqueous suspension - "shake before using" - but that probably isn't going to change much with time anyway.)

 

So, my feeling was to do an initial test fairly quickly, and then follow-up tests later. Given the fairly catastrophic failure of all but one sample, I think I have some rethinking to do first, see lower down.

 

I also purposefully didn't clamp the patches, as I suspect that you can't clamp patches on many concertina repairs. Someone who knows better, please advise! So I pressed them on firmly with a finger tip and hoped for the best.

 

I think I have worked out what went wrong with my initial patching experiments though, and again, experienced people please feel free to comment. To make it easy, I punched disc patches, and glued them on hairy side down. I suspect the hairy surface absorbed all my glue, and so the joints were starved. Normally, the leather would have been heavily skived to make an invisible mend. I could learn to skive my discs but that might set science back years! I think an easy workaround is to glue the discs on shiny side to shiny side. This is only an experiment in adhesion, not in cosmetics.

 

The logical place to test this is the "control" sample, which has no treatment, but also failed the adhesion test. I'll rerun that test with the patch reversed, and proceed from there.

 

I suspect we will find that most of the treatments will still impede glueing, and will have to turn our minds to ways to remove the treatment when gluing is required.

 

Patron saint of bellows? That's going to require at least two miracles, isn't it? Some way to go yet!

 

Terry

[Frank Edgley]

As far as making leather, which may be porous more airtight, I have found something which may be of assistance. If you go to a camping supply store, the is a fix for leaky seams on tents. It come in a tube, dries clear and remains very flexible on drying. I have tested before and after with several pieces of leather, and found that it very effective, reducing leakage due to porosity to near zero. Since there may be various makers and formulations, I would recommend trying this out on a piece of scrap leather beforehand. I believe the brand available here in Canada is made by "Coleman". The downside is that, since one of the ingredients is, I suspect, silicone, it is difficult to glue onto afterwards. This should not be a problem for this application since you are unlikely to glue anything over an existing gusset. It is a liquid in a tube and can be painted on porous gusset leather with a fine artisits paint brush, avoiding other areas where you may want to glue something at a later time. It could be applied on the outside or inside. If the leather on your bellows gussets is porous, what do you have to lose? The next step is probably a new bellows.

Edited July 13, 2014 by Frank Edgley

[Terry McGee]

That would presumably be this product, Frank:

 

http://www.coleman.com/product/seam-sealer-and-outdoor-repair/2000008865#.U8HmmfmSyao

 

"Stop the rain from dripping through your tent seams with help from a Coleman® Seam Sealer with Brush Top. The built-in applicator pad allows you to work the fast-drying, water-based urethane formula into seams and corners to permanently close small holes on tents and other outdoor gear."

 

So, a urethane product, but water based. But certainly worthy of consideration. This being a tourism area, there are several camping stores in the village. I shall enquire....

 

Thanks, Terry

[Rod]

My unsubstantiated guess is that the 'WOLY' shoe cream that I apply to my bellows is initially liquid enough to be absorbed into the leather and subsequently, as the months roll by, begins to solidify sufficiently to seal any wear and tear that might lead to subsequent leakage of air. I re-apply the shoe cream when I guess that the cream is drying out to the extent that it is perhaps beginning to lose too much of its pliability and is itself in possible danger of beginning to crack up. The next application of cream probably helps to rejuvenate the previous application. The cream certainly exhibits lubricating properties which are, I am sure, of benefit to the free movement of the bellows.

 

I have a hunch that the 'WOLY' cream is perhaps a little more liquid and consequently longer lasting in its effect I than the old 'Meltonian' brand that I used to use way back.

[Terry McGee]

Sounds like a reasonable assumption, Rod. I suspect the Zorbel Leather Conditioner is a similarly formulated goup. It's more liquid - like sunscreen - in a squeeze tube, rather than the older cream-in-a-jar style.

 

I guess testing longevity is something else we should do (that will obviously take a little longer!).

 

Seems like almost anything will improve the airtightness of the bellows. It's the other characteristics - ease of application, effect on flexibility, ability to patch later, tendency to migrate, mean time between treatments, long-term effect on leather and good-old "other, please specify" that we need to assess as well. Nothing's ever simple, is it.

 

I've re-glued all those discs shiny-side to shiny-side, so tomorrow I'll have fun popping them. Even the PVA doped one that finally blew out at 60psi was a bit of an anti-climax. Here's me keeping my head down with safety goggles and hearing protectors on, gingerly winding up the pressure while monitoring flow, expecting at any time to be assaulted by a devastating shock-wave, and all it did was go psssstttt.

[Rod]

I can't bear all this suspense, Terry !

[Frank Edgley]

As for the product, I'm not sure. The one I have used is in a tube. I wouldn't use the applicator as shown in the picture, as it would get all over.

[Terry McGee]

I can't bear all this suspense, Terry !

 

Sorry! Hang in there, I suspect we're in for a bit of a ride yet!

 

On the cheerful side, I think we are gaining on it....

 

Terry

Edited July 13, 2014 by Terry McGee

[Terry McGee]

As for the product, I'm not sure. The one I have used is in a tube. I wouldn't use the applicator as shown in the picture, as it would get all over.

 

Perhaps this one then?

 

http://www.coleman.com/product/seam-sealer-and-outdoor-repair-kit/2000004569#.U8MPpfmSyao

 

"Stop the rain from dripping through your tent seams with help from a Coleman® Seam Sealer and Outdoor Repair Kit. The fast-drying, water-based urethane formula permanently closes needle holes on tents and other outdoor gear. Each kit includes a 0.75-oz. tube of Coleman® Seam Sealer, a brushtip applicator, a 0.5-oz. bottle of Coleman® Cure Accelerator, an applicator brush and a convenient carry pouch."

 

There's also an aerosol silicone-based product:

 

http://www.coleman.com/product/pro-techttrade-water-repellent-aerosol-spray/2000009210#.U8MQefmSyao

 

Terry

[Terry McGee]

Getting back to the patching question, I think I might have to put that on hold until I improve my leather-gluing techniques further. I found none of the patches difficult to peel off their samples, except the PVA pre-doped sample. (I created a new one of these, as I'd destroyed the old one.) Maybe I'm setting my standards too high? (Don't remember ever being accused of that before!)

 

I also tried some different leather (in case my old leather coat had been treated with something strange), but similar results. I also tried using shoe glue instead of PVA and got much better results, which raises the question why do we use a wood glue rather than a contact cement? So, more questions than answers at this point.

 

I'll go off and mull over where to go from here.

 

Terry