Gluing wood

[Hardwicke]

Slightly off topic I have to mend the base of a clock. It is wooden and supports it. Smallish clock about 6 inches by 4. Should I glue the broken base with PVA or use a contact adhesive? I'm concerned the PVA is very hard and if not clamped correctly will show whereas the contact might not have the strength over time. It also applies to the baseboard construction I'm about to commence (balsa to pine).

[Will L]

PVA every time. You will need to clamp it up tight so that the glue squeezes from the joint, but assuming you get the pieces well aligned and wipe off the excess glue it shouldn't show. At very least it will allow you to assure the parts are well aligned before the glue goes off, which is much very much harder to achieve with the contact adhesive which will also form a thicker layer between the parts than the PVA will if well applied.

Will

[Terry Bendall]

With more years of working with wood than I care to count, I would support Will's idea of using PVA for this job. If after applying the glue it is difficult to apply pressure with a clamp, or perhaps you don't have anything suitable, then push the parts together by hand, apply some masking tape to hold the base in place and then leave to dry under a weight of some sort. There are lots of different types of PVA glue but one of the most effective is Resin W.

Terry Bendall

[nigelcliffe]

PVA is an "old standby" and generally reliable if used correctly.

However there are alternatives which are now readily available to the domestic user; aliphatic glues (look like PVA, but seem to work a little bit differently) and a number of urethane based solutions. I'd probably use one of those.

The other "old standby" is epoxy resin, not the tubes of 5-min or 24 hour, but in liquid form with optional fillers such as "West's System". Probably a bit expensive to buy the tins for one job, but a remarkably useful product. I've used it to repair a bent-wood chair where the wood was splitting under the strain of the tightest curve. The job took a fair bit of planning, particularly making various clamping blocks from scrap wood, but was basically soak the split area in West's, cover with cling-film, then clamp blocks and clamp it. Leave to dry for a couple of days to be really sure. Once sanded back and a few minor gaps filled, it was very hard to spot the repair.


- Nigel

[jayell]

If it is an antique or fairly valuable clock then do not use pva or any modern glue as this will not be welcome to any subsequent owner, old fashioned hot animal glue would be better but getting advice from a clock restorer would be best. If it is a mass produced modern clock then use glues as suggested previously.

john

[Hardwicke]

Thanks guys.
I don't think it is antique (but will check before applying the glue).

Michael.

[ginger61]

Is "cascamite" still available? As I thought that was the glue of choice for older pieces.
Cheers, Nick.

[Terry Bendall]

Is "cascamite" still available?

Yes it is. see for example http://www.axminster.co.uk/cascamite-po ... -wood-glue. I have not has reason to buy any for a long time but apart from the souce listed who do mail order, it should be possible to find it in some shops.
It is also known as Polymite.

I thought that was the glue of choice for older pieces

Depends on your definition of "old" Nick.

Cascamite is a synthetic resin glue that has been around for perhaps 65 years or so. Proper antiques would as John Lewis said, have used animal glue, also known as Scotch glue and applied hot.

Terry Bendall

[ginger61]

Terry,
If I recall, you made up enough to do the job and it was a brownish colour. I wasn't refering to pre raphaelite but a bit more modern I had thought that with H&S you couldn't get it anymore as the last time I used it was the mid 80s when repairing the odd wooden item in a public school!!!! So it had to blend in
Cheers,
Nick.

[Natalie Graham]

Proper antiques would as John Lewis said, have used animal glue, also known as Scotch glue and applied hot.

I remember my Dad bringing me a tin of that from work for something I doing when when I was about twelve.
He said standing it on the end of the Rayburn would get it hot enough.
He said I should have known to take the lid off first.
I said he should have told me.
I don't think we ever did get all the lumps off the ceiling

[jayell]

I remember my Dad bringing me a tin of that from work for something I doing when when I was about twelve.
He said standing it on the end of the Rayburn would get it hot enough.
He said I should have known to take the lid off first.
I said he should have told me.
I don't think we ever did get all the lumps off the ceiling

[Terry Bendall]

If I recall, you made up enough to do the job and it was a brownish colour

The Cascamite that I used to use was a white powder that was mixed with water. If you mixed too much is would of course go hard nd would be wasted.

I had thought that with H&S you couldn't get it anymore

There are ver few hazards and with the quantities normally in use these are minimal. As with anything else, read the safety precautions and then follow them.

He said standing it on the end of the Rayburn would get it hot enough.

The correct way to melt scotch glue is in a double pot. The outside pot is filled with water and the inner pot contains the glue. Back in the 1950s when I started at secondary school the woodwork room still had the gas ring to heat the pot and when we did gluing up everything had to be got ready and all the windows closed because the glue started cooling as soon as it was taken off the heat.

Cascamite was a better option which I used when I started at teacher training college but these days PVA is much more convenient to use.

Terry Bendall

[Alan Turner]

You could of course use Aerolite 360 - the glue that was developed to glue the Mosquito together - as well as Cascamite.

However I would use Titebond - a PVA derivative that is use by musical instrument makers.

regards

Alan

[John Palmer]

Terry's memories of using scotch glue are much the same as my own, also in 1950's school woodworking classes - our headmaster taught the subject as an 'extra', though I don't think he would treat my subsequent efforts as much of a testimonial to his teaching skills. I think we had a thermostat-controlled electric ring rather than a double pot to keep the glue at the right temperature.

At http://www.youtube.com/watch?v=21sL6XLM02Y I've found a video of the glue in use - the speed at which the glue in a joint along the edge of oak boards 'grabs' and holds is extremely impressive - you couldn't do that with PVA!

Apropos the DH Mosquito, am I correct in recalling that an early problem encountered with plywood construction was the retention of unventilated voids, the moisture in which degraded the glue involved to such an extent as to lead to structural failure? Can't now remember whether this was a reference to the glue between components or the glue between the layers of ply (if different). I think the solution proved to be ensuring that air could circulate to the interiors of such voids, so ensuring that the moisture could evaporate.

I have had a couple of 'interesting' encounters with sealed tins subjected to a heat source...

[Natalie Graham]

The correct way to melt scotch glue is in a double pot. The outside pot is filled with water and the inner pot contains the glue.

Yes, Dad brought the glue melting pot home with him the next night and we tried again. He didn't think it worth it just to stick my school homework together. He was quite good at short cuts like that that ended up making a lot more work in the long run.

[Alan Turner]

Apropos the DH Mosquito, am I correct in recalling that an early problem encountered with plywood construction was the retention of unventilated voids, the moisture in which degraded the glue involved to such an extent as to lead to structural failure? Can't now remember whether this was a reference to the glue between components or the glue between the layers of ply (if different). I think the solution proved to be ensuring that air could circulate to the interiors of such voids, so ensuring that the moisture could evaporate.

...

It's certainly why there are no original flying examples left. There is an Australian flying Mosse but that was built from scratch and is actually impregnated with epoxy resin (West system as used in wooden boats these days). If epoxy had been around when the Mosse was built it would have been much stiffer and would have lasted for years.

Never mind the Boeing 787 the Mosquito was the first composite aeroplane!

regards

Alan

[Terry Bendall]

the moisture in which degraded the glue involved to such an extent as to lead to structural failure?

Some interesting information here. http://en.wikipedia.org/wiki/De_Havilland_Mosquito

Terry Bendall

[Crepello]

Apropos the DH Mosquito
...

It's certainly why there are no original flying examples left. There is an Australian flying Mosse but that was built from scratch and is actually impregnated with epoxy resin (West system as used in wooden boats these days). If epoxy had been around when the Mosse was built it would have been much stiffer and would have lasted for years.

Never mind the Boeing 787 the Mosquito was the first composite aeroplane!

regards

Alan

The Mossie can lay claim to being the first multi-role combat aircraft too. The Canberra was developed to a spec for a Mosquito replacement, and the search for a Canberra replacement led to TSR-2 and thence the Tornado.

Actually, the last original flying example met its end due to incorrectly adjusted SU carburettors, as the fact that a corrective measure had been developed quite early on had been lost from the maintenance procedures. The recent almost-new-build took place in New Zealand, and was delivered to the project sponsor in the US, just before he ran into financial trouble, so I do not know the aircraft's current situation.

Used in its construction were veneers supplied from the same North London firm that supplied wartime production, and the tools and jigs used for the new build have been retained, so there is optimism that further examples may follow.

I recall a story that those inventive chaps at De Havilland's Hatfield site were the first to recognise a use for those ply 'offcuts' they found around the factory as model railway sleepers, once sliced and fitted with small metal eyelets for rail attachment. So the progenitor of our Brook-Smith system was born.

[John Palmer]

The Mossie can lay claim to being the first multi-role combat aircraft too. The Canberra was developed to a spec for a Mosquito replacement, and the search for a Canberra replacement led to TSR-2 and thence the Tornado.

Much to my regret I narrowly missed an opportunity to be a passenger on a low level sortie by one of 80 Squadron's Canberra PR7's out of Brüggen in 1964. The Canberra was another great design and my contemporaries who did manage to get such a trip came back from it white faced!

Actually, the last original flying example met its end due to incorrectly adjusted SU carburettors, as the fact that a corrective measure had been developed quite early on had been lost from the maintenance procedures.

Is this a reference to 'Tilly' Shilling's flow restrictor, the device introduced to prevent carburettor flooding and thus negate the Bf 109's combat advantage of being able to bunt into a negative G manouevre?

[Crepello]

Actually, the last original flying example met its end due to incorrectly adjusted SU carburettors, as the fact that a corrective measure had been developed quite early on had been lost from the maintenance procedures.

Is this a reference to 'Tilly' Shilling's flow restrictor, the device introduced to prevent carburettor flooding and thus negate the Bf 109's combat advantage of being able to bunt into a negative G manouevre?

Right person, wrong fix! The flow restrictor proved to be an intermediate fix. The final comprehensive fix, involving modifications within the float chamber, was tested and approved during Spring 1942. Eventually, somehow, the correct adjustment procedure for this 'fell out' of the approved maintenance documentation, which allowed the negative-G myth to resurface as fact, so that performance weakness became accepted as 'one of those things' in the Warbird Merlin fleet.

Forensic examination of the remains of RR299 revealed the probability that her carburettors had had this adjustment taken so out of range, by the licensed overhaul contractor, that the fix was ineffective. This was demonstrated by replicating the settings on a BBMF installation. Ironically, RR299 was on her last display season with BAe when she crashed, as the intention was to transfer her to the care of the BBMF for the future. The negative-G she had suffered was not due to any extreme maneouvre, merely the rolling rotation to enter a wing-over, which on a twin-engined layout of course implies the descent of one engine.

[jayell]

Since this topic has moved on to the use of moulded plywood I think I'm justified in mentioning my experience as I worked for a company that made extensive use of moulded ply in furniture production back in the mid 50's to mid 60s.

Hille, sadly no longer in business as a manufacturer, had been using hydraulic presses for laminating before WW2 but it was the development of urea formalehyde and resorcinal glues in the late 40s that enabled them to start producing moulded plywood chairs. The most succesful of these were the Hillestak which used a formed ply seat and back linked by a laminated spine, this was followed by the QStak which had the seat and back in a one ply moulding on a simple metal leg frame.

Their interest in using moulded ply led to them (or rather their designer, Robin Day) into using other materials like rigid polyurethane foam and eventually, in 1963, to their biggest success the polypropylene chair and its derivatives which are still to be seen all over the world in places like hospitals, offices or schools.

I had joined the company as a trainee workstudy engineer in the chair shop, but got involved in much more than 'watching people working' as the managing director expected the management team to turn their hand to everything from sweeping the floor upwards. Mrs Hille was occasionally to be seen sewing chair covers herself if there was an urgent order to get out. I spent several years in the Haverhill factory where the tubular and other metal work was made and it was there I made contact with the GER. It was there too that I became acquainted with turning metal and acquired my first lathe, an ancient small, possibly modelmakers, one.

I have always regretted that 'domestic problems' led me to leaving the company but I still have an involvement of sorts as my youngest daughter is working in the modern office building Hille built in St Albans Road, Watford around the time I joined them and has contact with a member of the Hille family fairly regularly. Cherill Scheer (nee Hille) very kindly signed my copy of commemorative book "Hille - 75 years of British Furniture Design" last year following a chat with my daughter.

It is over 50 years since I saw veneers being moulded, but as far as I can remember the process consisted of laying a pre-cut sheet of beech veneer into the mould, then more sheets were passed through rollers to coat both sides with glue and laid up in the mould, with a final decorative veneer being laid on top. The mould was than closed by a hydraulic ram and the mould heated if memory serves me correctly to set the glue. I think the moulds were built up from sheet ply by company 'toolmakers' .

http://www.lovelyandcompany.co.uk/seati ... stak-chair
http://www.loft.co/qstack.html
http://www.design-technology.org/polypropchair.htm

I nearly forgot to mention that the cabinet makers still used hot animal glue for laying decorative veneers when making traditional style furniture.

John