Thread: CA cure time

That Q ranks right alongside "how long is a piece of string?"

A. Depends!

CA glue doesn't "air cure" like traditional PVA (water based) style adhesives which require the moisture in the glue to evaporate. The CA cure relies on atmospheric humidity and surface moisture as its catalyst, and can also be triggered by an alkaline substance (bicarb of soda).

So, unaided cure time depends on a few factors, the moisture in the air, or the moisture content in one or both pieces to be bonded, the pH of the material to be bonded, the volume of CA etc.

Ordinarily it should set within seconds in an ideal joint situation but can take several minutes if the atmosphere is very dry, and the workpieces dry as well. In some situations, in wood turning the CA may not cure at all i.e. deep voids in a very dry workpiece. Many a turner has been showered by uncured CA glue as they turn through a void filled with CA.

Thank you, the main reason I ask is there is a split/crack in some timber and I was looking for a glue thin enough to flow into split. Epoxy is too viscous and I don’t have a pressure pot.

Any other suggestions? This is all in aid of giving me more workable timber and not having to cut round the dodgy bits.

In that case I'd say the cure time is largely irrelevant. Flood the crack and leave it overnight. I wouldn't clamp the joint or you'll just reintroduce the stress that caused the crack.

I agree with Jack, flood the crack then leave it to cure for as long as possible. Woodturners regularly do what you are asking about, and it gets used a lot to stabilize areas of punky wood.

The other things to be mindful of are that,

• the CA will wick into the grain either side of the crack and may be apparent in the finished item as a glue line (aka PVA under stain)
• it may also set / cure before the depths of the crack are flooded by the CA i.e. it self forms a dam / barrier.

So, try it but be cautious and check the blank regularly whilst turning.

And be sure your eyes are protected when you are turning it, even if you know the glue has fully set. You don't want CA in your eyes. DAMHIKT!

Thank you all, this will be a wax finish but not even sure if I will use. I’d definitely not like to see a visible white crusty line in the piece. I’m going to make a marking set of guage, awl and workshop pencil from Carrols. All in the Gidgee posted I. Hand tool making. I will photograph the split. And post. And tomorrow I’ll have to contact Jim and co to repost me a copy of the workshop pencil instructions as I’ve lost them.

Originally Posted by Fumbler

Thank you all, this will be a wax finish but not even sure if I will use. I’d definitely not like to see a visible white crusty line in the piece. I’m going to make a marking set of guage, awl and workshop pencil from Carrols. All in the Gidgee posted I. Hand tool making. I will photograph the split. And post. And tomorrow I’ll have to contact Jim and co to repost me a copy of the workshop pencil instructions as I’ve lost them.

A visible white crusty line only occurs when the CA cures very rapidly through too much accelerator, or when there is excessive moisture in the piece/s to be glued.

Used correctly the cured CA should present as a thin line in hairline cracks.

Why the cured CA may be visible under a finish is the way it wicks into the surrounding wood fibres and natural vessels in the woods grain. In some woods it can wick a considerable distance from the crack. It changes the woods properties and how it will accept a finish. With a wax finish the wax will easily burnish into raw wood but will be resisted by the CA, so you may have a spotty finish i.e. different sheen levels between the natural and glued areas. That applies to most finishes and glue excess on the surface of wood.

Thanks again, well here are the splits you will notice one part where the epoxy didn’t flow into, hence my question. Unless of course there is a very thin epoxy that I can let seep into.
IMG_8023.jpg IMG_8024.jpg This has been book matched but only in so much as to split to get 2 pieces.
and here is the split as it is right through the piece. You will also now the pencil marks of the size needed for one part of the set. But as noted earlier, if I can save it all with filler all the better.
IMG_8025.jpg

If you wish to stick with epoxy, warming the work and also the epoxy mix will lower the viscosity of the epoxy to allow it to flow / penetrate deeper.

Originally Posted by Fumbler

Thank you all, this will be a wax finish but not even sure if I will use. I’d definitely not like to see a visible white crusty line in the piece. I’m going to make a marking set of guage, awl and workshop pencil from Carrols. All in the Gidgee posted I. Hand tool making. I will photograph the split. And post. And tomorrow I’ll have to contact Jim and co to repost me a copy of the workshop pencil instructions as I’ve lost them.

I routinely use CA on fine cracks as a filler, its work just fine for me. But then most if not all my blanks are dark-coloured, so glue lines are non-existent. The CA I use is the cheap stuff, Bunnies used to sell a card of 5 or maybe more $1.62 I always bought $10+ never had an issue with it

Originally Posted by hughie

Bunnies used to sell a card of 5 or maybe more $1.62

They still do:

Just a moment...

I find them so much more convenient than bottles that seem to clog at the tip no matter what I do.

Originally Posted by Mobyturns

If you wish to stick with epoxy, warming the work and also the epoxy mix will lower the viscosity of the epoxy to allow it to flow / penetrate deeper.

cheers Moby, I think I’ll go this route, and warm the wood/epoxy. This is the only piece I have so I’d like to keep as much of it as workable as possible. It’ll be nice to say “all these pieces came from the one block.

as others have said flood and leave is the answer. Especially if deeps ones. Don't rush unless you need to

Wil glue your fingers together within seconds while you try to hold it all together. Will take many minutes for the original join to set still.