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Cascamite and Iroko

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SkinnyB

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First time using Cascamite and I am a very disappointed. Looks like I have got to cut these off and re-glue some how!
Followed all the instructions on the container to the word. Sanded both parts to be glued then wiped before glueing.
Clamped, brought into house and left for 48 hours.

I then cut the shepards crooks yesterday. Went to dry fit the gates this morning and this almost fell on my head!
Different glue? Something I have done wrong? Any help?

I had loads of squeeze out so quantity wasn't an issue. Both faces had previously been through the thicknesser so I know they were flat and looked good on a dry run. As you can see from the pictures it pulled a very little amount of wood with it.

Thanks

IMG_6776 by jamie skinner, on Flickr

IMG_6777 by jamie skinner, on Flickr

IMG_6778 by jamie skinner, on Flickr
 

Trevanion

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That would be the oils in the Iroko not allowing the water-mixed glue to stick, you need to wipe down gluing surfaces with methylated spirits or a similar alcohol before applying glue.
 

SkinnyB

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Oh right ok, ill give that ago. Fun doing that inside in the 150mm deep mortices.
 

Trevanion

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Best you figure it out now rather than after you've glued up the gate and it falls apart after a short while! Goes the same for painting it too, if you're using any form of paint it needs to be "primed" with meths first before putting it on otherwise the paint either won't stick or the oil will bleed through the paint.

It's a right pain to work with.
 

deema

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I’ve had the same issue only once before, it was due to the cascamite having gone off. It could be the oils in the wood, however, both surfaces look wetted and it appears it’s the glue itself that’s failed.

When you mixed up the glue, did it go crumbly and then after a fair amount of mixing go smooth? If so, that’s the glue gone off. When it’s being mixed (I always add all my powder and then add all of the water and mix up, rather than what it says in the tin) it should go stiff a bit like pastry and then go smooth. If it falls apart into crumbles and takes a bit to mix to a smooth paste it’s been exposed to moisture and gone off. The time I had it the glue was from a brand new tin that I’d just opened.

Just as an aside, I would definitely add a couple of dowels or dominos, glue does not hold up to shear stresses very well.
 

AJB Temple

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I have my suspicions that they have changed the formulation of Cascamite fairly recently. I've been using it for about 30 years, but my memory suggests it used to be better. Probably me.

Apart from the excellent advice above, remember too that curing Cascamite is VERY temperature sensitive. At 10 degrees C for example it remains workable for a good couple of hours and if you don't raise the temperature will take an absolute age to achieve strength.

With that detail on the gate, I would probably add a dowel to be on the safe side.

Looks like they will be very nice.
 

Mike Jordan

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Cascamite is as good as it ever was! I've been using it for nearly sixty years is now but never on Iroko, aforamosia or teak. They contain oils which mean you must use two pack epoxy glues. Foaming polyeurathane claims to be suitable but I don't trust it. Ignor the claims that you can degease the timber with solvents. Most are health and/ or fire hazards and have little effect if any. It's a myth expounded by those who don't want to spend on the correct glue.Epoxy is expensive but as a boat builder I have used lots of it with great success on the above timbers. I feel that you are always better with a joint rather than just edge jointing this type of timber.
 

Sheffield Tony

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Well, I glued my iroko front door together with Extamite (Screwfix cascamite knock-off). No degreasing. It has not fallen apart yet in the decade or so it's been in use.

I'm inclined to agree maybe the glue was off - unless it was allowed to move during setting / before it was fully set ?
 

woodbloke66

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Mike Jordan":3iy7c5d4 said:
.Epoxy is expensive but as a boat builder ....
You probably need decent stuff (West) for bateau building, but for ordinary cabinet/exterior work, go to Poundland. A twin tube of quick set epoxy will set you back a round pound and it's good stuff....I've been using loads recently and it's saved me a small fortune over the roughly £5 stuff - Rob
 

Jacob

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It's basically a weak joint with too much cross grain but it wouldn't be the glue failing if you'd done it properly in the first place, it'd be the wood.
Looks like you've wiped it on too thin, and/or left it to dry too long before joining, and/or not clamped tight enough. The glue has only taken at the points where you can see that the wood has broken out.
Do it again but brush the glue on thick on both faces, clamp it quickly and tightly so there's a bead squeezed out all around the join. Where there isn't a bead there is not enough glue.
 

Hattori-Hanzo

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New cascamite is no where near what it used to be.

The original cascamite "one shot", think was made by Bordens was far superior IMO to this new Polyvine trash they sell now.
I jest, Cascamite is still a great glue just not as good as it once was.

We've been using Iroko for our external joinery for decades and the only glue we use on it now is a red 2 part resin based . Sorry I don't know what its called off the top of my head but will find out tomorrow.

All other glues we've tried had similar results to yours.

like mentioned above the natural oils in Iroko will resist any other glue.

DO not waste your time and money on expanding polyurethanes for Iroko they are useless.
Degreasing wont help either, it may help to provide a stronger glue line initially but eventual it will fail, sooner if exposed to the elements. (in an application like yours, maybe not so evident on a gate with tight fitting mortise and tenon joints)

Ideally I'd try to get a tenon or lose tongue in that joint to give it a bit more strength, then with the right glue you should be good to go.

Iroko is a great timber for external use and will last for years and years but unfortunately needs the right preparation and materials when being used.

I hope you're not planning on painting it as that's another long story...........
 

Jacob

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Hattori-Hanzo":15wljmkj said:
....
The original cascamite "one shot",
? Was water mixed I thought. Nice stuff to use.
.....
All other glues we've tried had similar results to yours.
The OPs glue has not itself failed - it's still there, in good nick, just as applied. Thats how it looks anyway.
The problem in the handling/application see earlier answer above
 

Hattori-Hanzo

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Yeah one shot was water mixed, we had large sacks and sacks of the stuff with what seemed like a very long shelf life.
The new Polyvine stuff seems to go off on the shelf in a matter of weeks. we recently threw away a brand new 3kg tube as it had gone bad, it's just not worth the risk to use it.
We never had a single problem with the older one shot stuff, it's a shame we ran out!

Could well be an application/handling problem, I've seen a similar thing on other timbers when the casco is mixed up with stone cold water. (always mix with slightly warm water especially in winter)

I've seen the same results many times on Iroko with other glues, and we tested quite a few until we settled on this red glue.
Down side to this red glue is it's nasty stuff to use, instant dermatitis if you get it on your hands and stains the skin like nothing else so gloves at all times.
Originally it was a powder and resin mix, if you inhaled the slightest amount of powder it felt like your nose and eyes were on fire. Thankfully they've since replaced the powder with a liquid which is much better to use.

I don't know the scienece behind it but thought that because of the oils in Iroko the moisture in the glue could not properly penetrate into the wood and escape causing the glue to over saturate and fail, leaving the shiny glue surface as shown in the photo. I wonder that shiny glue would scrape off easy as any thing?

The 2 part resin glues chemical reaction seems to bond Iroko much better, no doubt it's the strongest wood glue I've ever seen but we only use it on Iroko/teak or if we know something is going to be exposed to extremes in weather conditions as it's expensive stuff.

Any thing else gets cascamite as despite my slating I do think it's one of the best all round glues.

Oh and don't get me started on accoya, no matter what the reps say you need a chemical glue for this stuff, which i do not rate one bit but I digress :)
 

Jacob

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Hattori-Hanzo":2podxk1m said:
......... could not properly penetrate into the wood and escape causing the glue to over saturate and fail, leaving the shiny glue surface as shown in the photo......
Looks to me that the glue is firmly attached to the wood on both pieces but the two layers have not been brought sufficiently into contact. Not enough glue, or gone off too soon, or not enough clamping.
 

Hattori-Hanzo

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resorcinol-formaldehyde? rings a bell. Could be the stuff but not sure, I'll have a look at the data sheet tomorrow.
 

Ttrees

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If it's not the glue, then it's the temperature.
I won't do a glue up in the shed until it's 13 degrees Celsius anymore.
I have made a wee mesh table that was lying around and use it for gluing inside now, and use a 1500 watt oil radiator which is underneath, and a big tent is over all of it, it gets possibly up to 20c (not to put too much trust in the cheap infrared gun thermometer I have.)
I have had good luck warming the parts beforehand a day or two in advance using titebond and evo stick waterproof.
I have never wiped down anything to remove oils as many don't agree with this, and those folks mention the wood needs to be freshly worked on, like no more than 15 minutes in advance.
I try to achieve that and if I can't I might do a light scrape.
There was a study on propellers that suggests it's a better method, and also suggests planing gives a better surface than sanding does.
Not done much stress testing apart from hitting a few offcut
blocks now and again.
I will dig this up as it was not believed the last time I brought this up....
Here is the article.
Chapter 9 of the Forest Service's Forest Products Laboratory Wood Handbook has a very useful discussion of wood adhesives.

https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.pdf

Not taking chances after having failed a few years ago thinking the room would be warm enough and the iroko door which needed work was next to the stove that does not work very well.
I'll not trust any temperature what's not been inside the tent now, until it's warmer weather again.

Tom
 

Hattori-Hanzo

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Don't know how the op did it but by the machining I'd guess it was made in section and pulled together with sash or G cramps before shaping, pressure shouldn't have been an issue?
I've done successful rub joints with casco on other woods that haven't failed like this, the wood gives before the glue line does.

glue starvation doesn't look to be an issue either.

Gone off too soon could well be a factor though casco has a pretty long pot life, though once it starts to skim over it should be discarded. However I have used it long into it's pot life with no ill effect.

I think temperature plays a big part. I suspect we've all used PVA in low temperatures and suffered the chalky effect and the PVA failing to stick, I'm certain its the same for cascamite as Ttrees has mentioned.
 

Trevanion

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This is an interesting discussion, the whole degreasing with meths thing is just what I was taught as an apprentice by someone who'd been doing it donkey's years so I've just stuck with it, never really thought whether it was the right or wrong way as it's always been "THE WAY" in my head :lol:. The way I looked at it was if the surface is free of oils the glue will stick since glue doesn't really penetrate that deeply into timber anyway.

I've been getting a lot of mileage out of the Polyurethane glues for the last 4 years or so because of the Accoya and have been using it pretty extensively on the Sapele and Oak stuff and haven't cropped up with any problems yet. Time will tell.

Tell me more about this "Red Glue" :)
 
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