Cascamite

[lurker]

I thought I would try this stuff as i have a repair job that might need some gap filling.

I experimented by mixing a small quantity to a "thin cream".
I glued up some scraps and this morning it seems to have worked fine.
I have questions (numbered for easy answering):

1. I left some in the tub maybe 3mm deep, this morning its sort of rubbery but flaky (bit like Feta cheese). does not fill me with confidence.

2. As it was thin, I can't see any gap fill properties. should I have mixed thicker (until its like PVA glue consistency).

3. Instructions say it needs longer to set in cold weather (makes sense) but what about subsequent performance?

4. What open time do I have?

 

[CHJ]

1. Correct mixing ratios are important, by volume 3.5 to 1, by weight 2 to 1
(For small quantities I use a small spoon, 7 level spoons of powder to 1 of water)

2. Runny Honey is the nearest I can describe it

3. Think you have mixed too thin, bring left over sample into warm environment (radiator) and it should set to brittle hard consistency.

4. Dependant on ambient temperature 20 to 30 mins in the pot, grab time dependant on wood porosity.

As an example the two rings of segments in this WIP took about 25 mins with no problems.

 

[thetyreman]

I thought I would try this stuff as i have a repair job that might need some gap filling.

I experimented by mixing a small quantity to a "thin cream".
I glued up some scraps and this morning it seems to have worked fine.
I have questions (numbered for easy answering):

1. I left some in the tub maybe 3mm deep, this morning its sort of rubbery but flaky (bit like Feta cheese). does not fill me with confidence.

2. As it was thin, I can't see any gap fill properties. should I have mixed thicker (until its like PVA glue consistency).

3. Instructions say it needs longer to set in cold weather (makes sense) but what about subsequent performance?

4. What open time do I have?

1. That's normal, it means it's not fully cured yet, wait until it goes rock hard, you should be able to pop it out the tub, it can take more than 24 hours, takes longer to cure than PVA from my experience.

2. you can vary the thickness by eye, I do it with measuring spoons 3.5 units of powder vs 1 unit of water seems just right, also add half the water in first, then the second half it'll be a better consistency.

3. It does need longer to cure in colder weather, I use a heat gun when it's close to 10 degrees on the joint before assembling it together, this speeds things up, you can do it with PVA as well, seems to improve the cure time.

4. You should have a good hour of open time.

 

[custard]

The 3.5:1 by volume ratio is critical. Personally I mix in two stages. Start with all the powder and half the water, mix until it resembles the crumbly mix you might use in baking. This first stage takes some determination, it's all too easy to think it's impossible and slop in some more water, stick with it and you'll get there. After that add the remainder of the water and mix up to a smooth consistency.

Temperature is critical, I'm nervous below 15 degrees C because the curing times can then get pretty extended. My workshop is heated but getting it up to 15 degrees takes a few hours on a frosty morning.

If I'm doing lamination work (as I often do), I leave a thick residue of adhesive in the mixing bowl, and a thin smear of adhesive on a mixing stick. I check the next morning that both of these are glass hard. I'd be very concerned if I found what you seems to have, a rubbery mix. In those circumstances I'd get the temperature and check again in another 24 hours. It could be old glue, too cold or too much water, but until your test glue is glass hard you can't trust the bond.

 

[lurker]

Thanks to you all

I was expecting "glass hard" but thought I had missed something.
I had guessed temperature was a factor but thought I had mixed to the correct ratios. Will "up my game" in this respect. Runny honey it is!

Looks like I'll have to bring "glue ups" indoors, but at this time of the year that's no different to using PVA, so nothing new.

...........one further thing; should it set clear ?

 

[Yojevol]

I'm using cascamite at the moment and over the last week or so. Workshop temperature has been 8-12degs. Have left the joints overnight and they've needed 12 hours or so to fully cure.
Brian

 

[Trevanion]

...........one further thing; should it set clear ?

It's not crystal clear but it does set to look a bit like translucent (Sandblasted) glass.

 

[Yojevol]

A couple of tips:-
1. clean mixing pot with hot water before residue sets
2. add water based stain if the glue is to be obviously on show
:lol:
Brian

 

[CHJ]

2. add water based stain if the glue is to be obviously on show

Spirit Stain does not appear to be detrimental either if added to and mixed with powder immediatly before water.
Spirit rapidly evaporates and does not cause a problem mixing.
Has not caused an adhesion problem that I am aware of, certainly stands up to turning loads.

You may need to take account of the liquid input to the mix of adding stains.

 

[worn thumbs]

My least favourite glue,I will concede that you can get nice thin glue lines.Thats about the extent of the good points.It takes ages to cure in low temperatures,mixing isn't easy and when cured it murders the edge of any tools you use to clean up the joint.

 

[thetyreman]

popping the glue out the tub is incredibly satisfying as well, genuinely one of the best things I've ever done and a true highlight of my life, maybe even the pinnacle of my life so far.

 

[custard]

I will concede that you can get nice thin glue lines.

Except you can't. The best glue lines are achieved with PVA. UF glues such as Cascamite are a long way behind, although they're still better than Epoxy in that respect.

Does that make UF glues bad? Not at all. Zero creep, their gap filling and water proof properties, and long open time, all makes UF glues invaluable for many applications like lamination or exterior work.

 

[deema]

I’ve found that Cascamite is a superb alround glue which is brilliant for laminations, all carpentry and joinery. The joints it produces for me are tight without causing gaps. Mixing with the sawdust of the stuff your making produces a really good filler.

I usually leave the glue for a couple of days to completely cure. I don’t remove the globbes of glue when gluing up as I find it’s easier to ‘chip’ it off rather than have a smeared area where I’ve tried to wipe it off. The smeared area is I find harder to remove as it has to be sanded. The globbes don’t seem to stick very well and don’t get pushed into the grain in the same way. I’ve found that a scraper such as a No80 is the best way of very quickly cleaning up by hand. (Or a wide belt / drum sander)

There is I know something that you can add to Cascamite to make it set in minutes. It’s been discussed on a previous thread, which I can’t now find. I tried it and it works very well. I don’t use it myself as I like the long open times for clamping.

Personally I’ve found that if the cascamite becomes crumbly it’s usually because it’s gone off, absorbed too much moisture before use. As it dries if it’s good I’ve found it becomes stiffer until rock hard and never crumbles. I used to mix my volume, but now find that mixing by weight is far easier. A cheap £5 digital scales off an auction site suffice.

I add all of the water to the cascamite and mix in one go. One thing I’ve also found is that if it’s good it transitions from a crumbly mix to smooth thick liquid very quickly. If it’s gone off it stays in the crumbly state for a while and needs a lot of mixing before it transitions.

 

[Trevanion]

There is I know something that you can add to Cascamite to make it set in minutes. It’s been discussed on a previous thread, which I can’t now find. I tried it and it works very well. I don’t use it myself as I like the long open times for clamping.

Phosphoric or Formic Acid? I think there used to a proper "Acid Hardener" you could buy from someone like Fiddes, I can't remember who though.

 

[custard]

If I've got a major lamination or veneering job I'll order in UF glue in liquid form such as Bordens. Cascamite (also a UF glue) is a convenient substitute for the odd job here or there, but Bordens has the advantages of different hardeners and different hardner ratios that can speed up or slow down cure times to compensate for different temperatures or minimise press times, and also mitigate problems such as veneer "bleed through" or the infamous "green tinge" with veneered Sycamore.

The problem with these type of professional UF glues is that the minimum quantities are still quite large and they don't last longer in storage than a couple of months. Airpress used to offer a good liquid UF adhesive in 1 litre bottles, but the smallest is now five litres. Still, if you have a big enough job in prospect the advantages make it worth it considering...even if you end up chucking half of it out!

 

[Phil Pascoe]

I believe that Aerolite (possibly an even better glue than Cascamite) hardener is formic acid, in which case the hardener for Cascamite is phoshoric. I used them both at one time and interchanged the hardeners - they both worked, but of course I didn't do stress tests or anything.

 

[Keith 66]

At school we used some UF liquid glue from Glues direct, think it was Borden, very good but the shelf life was 4 months & then it went off.
Went over to using cascamite as less wasteful. In my own shed i still use Aerolite 306 & it is better as it doesnt have the air bubbles in it that cascamite has.

 

[custard]

Aerolite and Cascamite are pretty different in at least one key respect.

Aerolite has the glue and harder applied to separate mating surfaces so that curing begins once the components are brought together, but once the two components are brought together the cure time is only a bit longer than slower acting PVA's. In practise complex glue ups that require lots of post cramping adjustment are best accomplished with Cascamite than Aerolite.

The other issue with Aerolite is there are occasions where you only want adhesive on one surface to minimise squeeze out, so you might apply glue to a mortice but not to a tenon. Most people I know who use Aerolite don't particularly like it for tenons full stop, they're concerned the hardner might get wiped away in a particularly tight fitting M&T, I don't believe that's a valid concern but anything that erodes woodworking confidence needs to be taken seriously. Where they do use Aerolite, and swear by it, is for edge jointing applications like strip canoe construction.

 

[Phil Pascoe]

If you use hardener for Cascamite, the acid is put on one side and the glue the other (I always did, anyway). If you actually mix the acid with the glue it sets in a couple of minutes and you'd not have time to assemble very much at all.

 

[custard]

That's interesting, I've never used a separate harder with Cascamite.

With a liquid UF like Bordens it all gets mixed up together, and even with the basic blend you have a fair bit of control over curing time by adjusting the volume of hardner that you use.