Correct Glues To Use
Posted 23 December 2003 - 07:47 AM
Q. What form of glues are recommended and how are they used?
Q. How are these joints then taken apart afterwords for subsequent repair?
Posted 24 December 2003 - 10:37 AM
For broken fretwork (on wooden ended instruments), frame corners and veneering, padpan cracks (usually with splices), reedpan cornerblocks (which are actually attached to the bellows frame), and bellows frame corners we use hide or a high quality PVA for these wood/wood joins. Some folk use resorcinol and other types of wood glues with good results.
For repairs to the leather parts of bellows (due to delamination, wear, punctures) requiring replacing leather parts or adding leather patches, we use rabbit hide or a PVA with a very high plasticizer content. I've heard that some folks use a contact cement (like Barge cement).
For repairs to card and hinge parts of the bellows we usually use the wood PVA.
For pad and thumbstrap delaminations we usually use a high-strength contact cement.
Some concertina parts are designed to be replaced periodically and so have easily reversible glues.
For bellows papers we usually use a weak PVA or weak contact cement (depending on the surface treatment of the leather part of the bellows the papers go against). The bellows papers that are sold on sheets or rolls which are "self-sticking"... are usually insufficiently sticky enough to stay on for normal use for very long.
Probably the part requiring the most frequent replacement is the valves. We use thickened shellac (as originally used). It grabs instantly, sets quickly, and "cures" to become extremely brittle. It'll hold the valve forever yet can be removed completely with a light scraping of the tip of a small screwdriver as it fractures into shards or powderizes. The thickened shellac is also dark brown so it's easy to see (to remove) even when there is just a very thin coat of it. Another nice thing about it is that you don't have to get off every last iota of it as new shellac will dissolve any bits of the old to make a secure bond.
I go into length about the this valve "glue" as this is the most often "injured" area we come across. We've seen lovely vintage concertinas with valves glued down with PVA, hot melt glue, and silicone sealer which can damage the wood (by being so strong to break the grain when removing and/or contaminating the surface to make it less "grippy" for other glues to hold well).
OTOH, when making a *temporary* repair (such as an interim bellows patch, a temporary glue should be used (in this case probably a "white" PVA).
There are so many parts and joins in a concertina, each having certain disassembly/reassembly procedures that I wouldn't be able to go into them all. Sometimes special tools are needed and often the glues need to be treated in different ways. For instance, no one MAKES thickened shellac - you have to make it yourself from flake (though aerated premixed seems to work okay if it's fresh enough). Some glues need to be heated, some need moisture, some need moving air....
Also, many glues are available *raw* though are typically procured in a premixed or "ready-to-use" state. Shellac and hide glues fall into this category. If you mix it up yourself you can control the viscosity, grab, set, flexibility/hardness, strength, and durability. The premixed ones are really very limited and degrade over time. OTOH, we've found that some glue makers will custom mix a batch to your requirements. Mixing glue up from flake or powder does NOT mean just adding water (or alcohol, thinner, etc.), but also glycerin, rosin, sugars, metal salts, alum, sulfated oils, etc.
Probably the best thing to do is "when in doubt, take it to a competent repair person".
Posted 26 December 2003 - 08:56 AM
A disadvantage with some 'wrong' glues for this job also is that if the used glue shrinks the valve may curve or raise and leak.
One little addition....for those not wanting to work with shellac ( I promote it too..)
simple starch glue is an alternative which has the little advantage not to cause 'dust' sticking in the reed slot. Easiest and cheapest of all is what is used for wall-paper.
One more specific site where it is essential to use glue that can allow pieces to be easily separated is for the sealing leather parts inside bellows frame, on the reed pan and so on....
Posted 26 December 2003 - 12:25 PM
I look forward to using this new found knowledge.
Happy Christmas to you all
Posted 27 December 2003 - 09:48 AM
Hi also suggested a "weak PVA". What is meant by a "weak PVA".
And finally, what's a "white" PVA?
Posted 27 December 2003 - 10:57 AM
I see a lot of mention of the PVA glues. Is the white glue sold as Elmers Glue-All an appropriate version of this? The PVA is considered easily enough removeable. Since I have seen it specified for glueing valves I wonder now about using it there. Is the objection because of residues left in the wood preventing a bond with shellac used in possible later repairs? Would PVA used in subsequent repairs solve that problem (no pun intended) ?
I'm not familiar with the use of shellac as an adhesive. I thought what I saw in the Lachenal was hide glue on the pads. I reattached one loose one with hide glue, which I am familiar with from violin work. It's impossible for me to say whether this old glue is original work on the pads or not. It's certainly not neatly done but it is darker than most old dried hide glue I've seen so I guess it is the shellac.
Now, as far as shellac and valves. How complicated is it do the right thing here? If it's a matter of mixing alums, salts etc. for those little dabs of glue I will look for a simpler alternative (wallpaper paste?, I imagine various things are used for that also). I mean, I'm willing to do a certain amount of mixing or preparation to avoid doing harm to an instrument but I was hoping for getting what I needed at the hardware store if I didn't already have it.
Posted 27 December 2003 - 11:20 PM
Posted 28 December 2003 - 03:29 AM
is the UHU Glue one of the fubberish impact adhesives? if so I have had to repair concertinas where this form of adhesive has been used and it had deteriorated and left an oily deposit in the wood. Making other other glues dificult to use. I have had other examples where the valves were literally falling off.
One form of impact glue uses a petrol base as a solvent (I think it's EVOSTIK Impact) this also 'strings' everywhere making its use frought with other difficulties.
Some years ago I was told to use PVA on valves and pads, by Steve Dickinson. I think there is a lot more awareness of residual effects now, particularly on valve assembly, and so I use PVA let down with water and I am experimenting with the use of brown gum.
Posted 28 December 2003 - 10:41 AM
Goran: Dave, we had this discussion some year(s) back and I spoke energetically against PVA on valves...opposing to Steve's recommendation....
I've tried to water down it too....it is NO good...it shrinks when drying (by natural cause...)
What is "brown gum"?....what is the aim of the experimenting...?
Sounds unnecessary as you have the basically perfect shellac and in my opinion evenly purposeful starch glue. The aims are: no permanent stickiness neither on wood nor leather, no shrinking(causes bending of the valve), no clotting (raises the valve and causes leak), should come off easily...just by hand and being easy to clean both from wood and leather (so the valve can be recycled if wished), and fixate the valve just enough not to come off from use
There may be interests in conflict here since the maker of an instrument wants the parts to work as long as possible (mostly...) while the user/repairer wants the parts to be possible to recycle and remount or replace easily and cheaply.
Posted 28 December 2003 - 11:00 AM
Frank, by Liquid Hide Glue do you mean the pre mixed product as sold by Franklin that I've seen in US hardware stores?
The PVA, or water soluble, white glue seems to be falling out of favor for valve glueing. In general, is the Elmer's brand inferior? It's just that that is what is most probably found in stores around here. I suppose I may not bother with it anyway since I guess something else will work for the pad work also. I still wonder, though, whether a sensible amount of the right consistency might not be a residue problem, that is, if the liquid of a new dab can allow a bond with the old spot.
Everyone is accepting shellac, it seems. I'm all for going that route if I can manage to come up with the right formula. Does this have any advantage over the hide glue I would mix up myself? What would I go in search of? Flake shellac? Additives?
Posted 28 December 2003 - 08:46 PM
I'm about to redo the chamois seal on the reed pan and bellows. What is the best glue to use?
Looking at the valves, they need replacing too, but seem firmly stuck with a solid, brown, transluscent adhesive (seems to disolve with moisture-my best guess: hide glue). Any hints on how to remove the valves without damage?
Thank you for sharing your knowledge and expertise. Greg
Edited by Greg Jowaisas, 28 December 2003 - 08:47 PM.
Posted 29 December 2003 - 10:17 AM
I very much agree with Richard. ‘Reversibility’ is the key.
I consider it good practise when approaching any restoration problem to ask:
- Does the job really need doing?
- What could go wrong?
- Can I get things back to the point I started from?…. and if not
- What is my fallback solution?
It should be noted that for at least the first hundred years of concertina production, probably only three or four types of glue were used; namely Animal/Hide glues, Natural Gums, Starch glues and Shellac.
While I have no great objection to the use of the correct grades of specialist PVA glues, with a few exceptions, I see little real need, or advantage in, departing from the original materials especially where restoration work is involved.
One difficulty, in the UK at least, is that virtually all the PVA glues easily available from hardware stores range from ‘difficult’ to bl**dy nigh impossible’ to reverse. This might be considered to be a positive advantage in some ‘structural’ repairs but if there is an equivalent strength ‘reversible’ bond available this will nearly always get my vote.
If you feel you must use PVA then look to Bookbinders or Conservators suppliers for specialist grades of Reversible or Plasticised conservation grade glues.
Do not be put off by the aura of mystique that seems to have formed around the use of hot animal glues.
They are cheap, easy to obtain and prepare and in my opinion, no harder to use than other modern ‘equivalents’. The commonest form is Scotch’ or Pearl’ glue which comes in the form of 1/8” diameter honey coloured, hard pellets. (These will keep virtually forever in a dry sealed jar).
Take a tablespoon full of pellets and place in a small glass jar, (baby food jars are just right) add just sufficient water to cover the pellets and leave 24 hours to soak in. The result is a thick jelly ‘glob’.
Take an ordinary domestic Iron, invert it and clamp it in a vice… a cheap variable temperature ‘hotplate’.
Place a small tin can, half full of water, onto the sole of the iron and stand your glass pot in this...... A cheap effective double boiler or 'Glue kettle'
Heat slowly whilst stirring and do not allow it to boil. If any scum forms on the surface, skim off with a small spoon. The glue is ready to use when it runs off your stirring rod with the same consistency as fresh engine oil. If too thick, add a little water and bring back up to temperature; if too thin, leave on a low heat for a little water to evaporate.
This glue is unusual in that it gains its initial set or grab from hardening as it cools, thereafter continueing to increase in strength as the water evaporates. It follows that a warm environment and a little pre-planning of the work is advisable so your glue does not chill too soon.
Have a play around with gluing up some scraps of wood, leather card and cloth to get a feel for the glue before starting your repairs.
For pads, simply place the new pad in position over the hole, add a small ‘blob’ of glue to the pad centre with the tip of an artists brush or even a matchstick, line up the button and lever and lower the leather ‘spud’ onto the glue. If you need to make later fine adjustments, for a few hours at least after initial set, you can soften the joint by holding the tip of a soldering iron near to, but not touching, the glue until it melts sufficiently to make your adjustment.
Place a tight fitting lid on your hot glue pot and it will keep without harm for several days, merely requiring re-heating and the occasional drop of water to keep the mix right.
To make life a little easier, there are ‘liquid hide glues’. I can’t say what brand Frank Edgley uses, but I have found Franklin’s ‘Titebond’ Liquid hide glue (LHG) to be an excellent reversible glue for all manner of repairs to wood card and leather (Available in UK and USA). These liquid glues are based on the same animal glues but have chemical additives that prevent polymerisation and thickening at lower temperatures. These glues rely solely on ‘drying out’ to gain bond strength and therefore have a slower initial grab (or conversely, longer ‘open’ time). This makes them more forgiving in their use, allowing for work at a steadier pace and giving longer for positioning and re-positioning component parts; at the expense, however, of a longer drying and hardening time.
Where a flexible joint is require you can add about 5% pure glycerine oil to LHG and this will act as a plasticiser. I have used this glue successfully for bellows making.
(Glycerine can also be used to plasticise PVA and Hot animal glues as well!)
Clean up excess with a damp cloth and reverse the bong with moisture and warmth.
If you dilute LHG with around 30-40 % of water, you will have a glue suitable for sticking valves though, personally I prefer the shellac as this give a faster set with less risk of you disturbing valves you have already completed.
Shellac is again simple to obtain, prepare and use. Simply buy a small bottle of ready made Shellac ‘Button polish’ or ‘French Polish’ from your local hardware or paint store. (Avoid ‘Bleached’ or ‘White’ Shellac).
Simply pour about ˝” into the bottom of a small jar (baby food again!) and leave with the lid off in a warm place for some of the solvent (alcohol) to evaporate off. This will take some hours so prepare ina advance. As this happens the polish becomes thicker and when it has lost about half it original volume give it a try on some sample material.
If too thin, it will tend to soak right into the leather and will dry stiff; if too thick, as Goran said, there is a tendency to form a thick layer lifting the valve off the wood and allowing for slight leakage. Trial, observation and a little common sense will indicate the right consistency. The ‘Glue’ can be reversed by the application of a drop of Methyl or Ethyl Alcohol (Meths in UK) or when perished, by scraping.
With an airtight lid, the thick shellac will last indefinitely and can be re-diluted if required with meths.
While on the subject of valves. I can’t think of any circumstance when I would re-use a valve. At a few pence (cents) each it simply is not worth accepting second best.
Another simple reversible glue useful for spot application such as valve fixing is natural gum glue of the type that is used extensively in schools and craft classes. The type I use is ‘Gloy Original Gum’ and is readily available in stationers and craft shops. (is this your ‘Brown Gum’ Dave?)
It dries by evaporation and is fairly slow setting but fully reversible with a drop of water on the leather of the valve. Coming in a handy tube, it is part of my travelling first aid kit.
It is this glue that I prefer for fixing bellows papers. It sticks well, allows ample time for positioning and any excess is readily and cleanly removed with a damp cloth.
Though I have never used the starch based glues favoured by Goran for valves, I shall certainly give it a try and, bearing in mind that a simple starch glue made from flour, water and glue size was the main glue used in all Crabb Bellows, I shall also give that a try on the next set I make.
I use a specialist leather contact glue, (probably similar to Dave’s ‘Evostik’ or The US ‘Barge Cement’), solely for the gluing up of English Thumbstraps.
Dave, I have used ‘UHU’ in the past and it is just like ‘Bostik’ which you may be familiar with. They are both , I think, styrene based and are equally vile and messy to use and produce long strings of waste. Any such spillages will dissolve or damage many wood (and leather) stains and surface finishes.
No room at all for these in my workshop.
While on the subject of ‘Nasties’….
Please avoid the use of all silicon based glues, sealants and wax polishes.
Silicon products can bleed into bare wood, even through minute cracks and scratches and can prove all but impossible to remove. The result is that if the joint has to be re-glued, nothing will stick and all traditional surface finishes I know are strongly repelled by silicon making cosmetic repairs very difficult.
I do use a synthetic glue for one other application – Gluing up the composition leather/felt/card sheets out of which I punch new pads. I use a spray can of general purpose upholsterer’s glue which gives a quick thin and even coating.
Simply spray on, assemble the ‘sandwich’ and press lightly for an hour or so.
Brushed application of other types of glue tends to soak in too far and causes hardening of the felt cushion and leather seal.
Posted 29 December 2003 - 05:02 PM
Posted 30 December 2003 - 12:45 AM
Reply:I don't know what you are talking about. The UHU I have used does not spill (it is a stick glue), does not sproduce "long stings of waste" or dissolve wood. Applied with a toothpick it is harmless (used by school aged children) and very easy to use, without any mess. It holds fast and is easy to remove by scraping with a screwdriver. I prefer liquid hide glue, but wouldn't hesitate to use UHU. It certainly isn't "vile". Maybe we aren't talking about the same stuff?
Posted 30 December 2003 - 08:04 AM
Thanks for your clarification,
I guess we have a 'Trans-Atlantic' problem with trade marks and product names.
The solid glue sticks you seem to be describing appear to be marketed over here as well under the name UHU 'Power Sticks'. These look to be a similar sort of product as a glue commonly known over here as 'Pritt Sticks'.
That being so, I would have no problem in using either product for fixing valves.
What I was referring to in my post, used to be sold by 'UHU' in the UK and was a colourless tube glue which smelled much like the 'airfix' plastic cement (used for model airplane kits) but had similar consistency as hard rubber when set.
It looks like this is still available in the UK and goes under the name, UHU 'All Purpose Crystal Clear' though I have no idea if it is sold in the USA and I havn't yet bought any to check that this is definitely the same stuff it used to be.
The UHU brand also market Cyanoacrilate superglues and some spray glues.
It seems that we may have both shortened the name to just the Brand name 'UHU' and thus arrived at a mis-understanding.
I hope the above clears things up.
Posted 30 December 2003 - 01:04 PM
the glue that I know as UHU and Bostick are stringy, rubberish, contaminating and I would agree with your word 'Vile'.
this may be what is marketed in the UK, I think its akin to Barge Cement but no doubt both companies have a wide range of products.
I don't agree with your over-riding view on reversability.
The only aspects where it holds true (in my view) are where maintainability is affected: typically bellows papers, and I am coming to the same view on valve adhesion.
I have recently re-valved instrument where a PVA was used, it certainly made the 'cleaning off' aspect into hard work and yes, the wood was sealed with the stuff, so I am starting to use gum, the last pot I bought was 'Golden Gum', but yes it is Stationer's supplies stuff.
The other glue jobs tend to be:
1. re- bushing key holes, the job is supposed to last another eighty years, and probably only needed doing because the original glue failed so PVA is OK there
2. Wood glue failure on veneers, frameing, and all manner of wood working activity, we want these to be perminent so PVA is OK there too.
3. affixing pads, again everything is perminent unless it is eventually discarded (all except the level arm of course) so PVA is again ideal.
4. Bellows repairs, (except the papers) again these repairs are intended to be perminent fixes, or at last last the remainder of the life of the bellows. PVA is effective and has the right properties, so I go with S.D.'s recommendation there too.
For most of use we use so little glue that hide glue and fancy shellacs are both impractical and uneconomic. I f you are using these media for other purposes as well then the case would be different
Posted 30 December 2003 - 02:58 PM
Goran:Agree concerning use of PVA, I use it too. I does stick but can be removed here with no hazards. However I don't quite agree regarding your "eighty years". In fact I mean rebushing often is wrongly neglected and ought to be done fairly frequently. It is a 2-3 hour job, not difficult (except for material...), and perfect button travel is absolutely essential for good 'action'. For non-riveted mechanisms it is even more necessary for the precision of the whole mechanism.
Dave:2. Wood glue failure on veneers, frameing, and all manner of wood working activity, we want these to be perminent so PVA is OK there too.
Goran: I'm a little bit more discriminating from principle though not always in practise..:-). 'In principle' I want "original type" glues to be used on all parts on an instrument close to original shape i.e being possible to conserve or by replacing parts keeping in 'original shape'
Dave:3. affixing pads, again everything is perminent unless it is eventually discarded (all except the level arm of course) so PVA is again ideal.
Dave:4. Bellows repairs, (except the papers) again these repairs are intended to be perminent fixes, or at last last the remainder of the life of the bellows. PVA is effective and has the right properties, so I go with S.D.'s recommendation there too.
Dave:For most of use we use so little glue that hide glue and fancy shellacs are both impractical and uneconomic. I f you are using these media for other purposes as well then the case would be different
Goran:Also agreeable (with reservations only for the possible selective 'conservation' approach). One motivation for my liking of starch glue being so absolutely simple, safe and cheap. Only disadvantage limited strength of fixation of course....but you just 'fix' it again...:-)
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