Cyanoacrylate and Quicklime

Has anyone come across 'Supa-Fix'? I picked up a box with two bottles of cyano and a bottle each of 'grey' and 'black' calcium oxide powder. The in-store demo was impressive, suggesting the combination produces a rock-hard, gritty textured substance that was able to joining wood to steel very effectively.

It would appear that the calcium oxide does more than catalyse a quick set, but presumably it undergoes some chemical change, perhaps creating a cyano-reinforced limestone?

I must admit, I haven't tried it yet, but it looks fun.

www.platinum-supplies.com/supa-fix-everbuild-adhesive-powder-kit-super-glue-apx4-ultra-strength-supafix.html

...And the bicarb is said to provide the small amount of water to cause the CA to set. However, I would have expected the calcium oxide to be devoid of moisture as it would immediately react with any (i.e., quicklime converted to slaked lime). So perhaps it does act as a catalyst. But it sound like an unpleasant and very reactive ingredient in the adhesive or cement.

Bill

Their blurb says 'like concrete' and it certainly is. I guess it could work very well to fill cracks in castings not exposed to temperatures above 180C.

Neil

I found a patent for a bio-adhesive composition and it says calcium oxide can be added as a `heat dispersant`, so its any ones guess what happens, other than as a filler.

superglue can react with many things. Ever drop any on your cloths. I had a minor burn on my leg after spilling a load onto my jeans .

sounds interesting, can think of a few unconventional uses depending on the cure time

Since calcium oxide is white, there must be additives in these powders, possibly fillers of some sort.

Geo.

It's been available in the motor trade for some years , but I expect the price will have come down somewhat now. I believe the filler powder may well contain a catalyst for the superglue. As other have said it forms a very hard and quick repair on may substrates.

Blasting soda is a free flowing baking soda, so it pours quite well. Makes for a very hard compound. Another we use as a wear strip is a combination of blasting soda and carborundum powder. I use it for a landing skid on my model planes.

Neil

I have heard that it can set cotton on fire.

As well as excluding oxygen, moisture and metal salts help CAs to go off. Humid clothes contain both, as well as large surface area in a small volume. I believe the "activator" sprays basically provide the metallic salts.

Most of these reactions are exothermic and the rate of reaction increases with temperature. Same is true of epoxy (Araldite) and car filler (MEKP?). I can tell you that if you add the hardener (or whatever it's called) neat, you can get that to burst into flames, which is presumably why it is generally supplied in a diluted form. With Araldite, if you heat it up, the reaction is quicker which can be useful, although initially it becomes more fluid - which can also be helpful.

Murray

As well as excluding oxygen, moisture and metal salts help CAs to go off. Humid clothes contain both, as well as large surface area in a small volume. I believe the "activator" sprays basically provide the metallic salts.

Most of these reactions are exothermic and the rate of reaction increases with temperature. Same is true of epoxy (Araldite) and car filler (MEKP?). I can tell you that if you add the hardener (or whatever it's called) neat, you can get that to burst into flames, which is presumably why it is generally supplied in a diluted form. With Araldite, if you heat it up, the reaction is quicker which can be useful, although initially it becomes more fluid - which can also be helpful.

Murray

I suggest that the 'calcium oxide' which is supplied is not actually quicklime, but slaked lime. I have three reasons:

1. Quicklime is fairly dangerous stuff, and is no doubt covered by all sorts of regulations. Slaked lime is much more friendly, even available at posh builder's merchants in lime mortar.

2. Quicklime is eager to absorb moisture, so has to be in a tightly sealed container, even in the factory where it is made. When this has occurred it turns into slaked lime (hydrated calcium oxide). So why not supply the non-noxious stuff?

3. If moisture helps c-a to polymerise, there is no advantage (in this respect) in adding a compound which absorbs moisture itself.

And it may be that the resulting set product with calcium is less soluble in water than with sodium (from bicarbonate) - thus extending the usefulness of the product.

But what do I know about it, anyway?

Cheers, Tim

Very good stuff Neil and useful too. Good filler for plastic parts when you have a hole to cover up. Cracked saucepan handles etc.

This may be off topic, but lots of people here seem to know about such things - My stainless steel hot water cylinder seems to have a very small leak, in the bottom. I am thinking of draining and cleaning out as best I can, then pouring some " stuff" in. Any suggestions ? Dia. is about 400 mm, max. temp about 70 C and will be wet all the time

Vehicle Radiator sealant? Sodium silicate aka water glass. Not sure how well it would adhere to stainless steel.

Bill

It's calcium oxide, the box wouldn't be plastered in warnings if it was slaked lime, and why claim it's something dangerous if it isn't?

Neil

It has an exothermic reaction with polyester fabrics too.

Your risk if you want your house flooded. The cylinder may be weak in that area and just waiting to fail in a big way! Is this a gravity system or at mains pressure?

As far as temperature is concerned, I've yet to see a hot water cylinder that is hot at the bottom. Water is a very good insulator.