Quantcast

Turning joints no longer seamless

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

ScaredyCat

Established Member
Joined
17 Mar 2017
Messages
958
Reaction score
9
Location
Suffolk
I'm having, yet another, problem with some of the stuff I've turned.

I sand and finish the piece, apply the wax polishing up and it's great. Beautiful seamless transitions that you can't feel at all. I have under my desk a vase that I've made for my wife and it's gone from this seamless jointing to something where I can feel every single joint. It's been a week since it was completed. I had a similar problem with another piece I did but that was fine for about 3 weeks before I could feel the joints.

The wood I'm using has been sitting in the house for months. I just cut it, glue it and then the following day turn and finish it. I'm using 502 wood glue if that matters.

I'm really not sure what to do to prevent this, obviously a failing of my process.

For the existing vase should I just remove the wax, re-sand and finish it again or is it a more fundamental problem?

.
 

CHJ

Established Member
Joined
31 Dec 2004
Messages
20,103
Reaction score
45
Location
Cotswolds UK
What you are feeling is Glue creep as the different pieces of wood move with atmospheric changes.
Even so called reduced creep PVA's still move sufficiently to suffer from this, no problem with normal cabinet making but becomes frustrating with contiguous surface joints.

It's for this reason I use Cascamite for any joints that are going to be at risk of this as it sets brittle hard and does not move, something that looks like being a real niggle for me now that Cascamite is going through a production problems.


If your items have stabilised somewhat in their intended environment you may improve things by re-sanding and finishing.
 

Alpha-Dave

Established Member
Joined
18 May 2015
Messages
206
Reaction score
31
Location
Durham
Many of the ‘segmented’ turnings that the members of our club produce have this after stabilising for a few weeks, some suffer less from it.

The cause is obvious: the wood has moved from when it was finished. How to prevent that are several options but none that combine cheap, easy or quick.

The best would be to use a stabilised material that is effectively 20-40% plastic. That is both costly and time consuming if you want to do it yourself.

The next options would be to use a single material that is conditioned to the same degree and has the same orientation (e.g. glued in a circle all end-grain to end-grain).

The next option if you want to mix woods and orientation is to semi-stabilise after making it. Build up a layer of clear coat (polymer or epoxy) getting to a significant fraction of a mm thick in many thin layer both inside and out would help, but the you lose the ‘feel’ of the wood.
 

ScaredyCat

Established Member
Joined
17 Mar 2017
Messages
958
Reaction score
9
Location
Suffolk
CHJ":3plts8gu said:
What you are feeling is Glue creep as the different pieces of wood move with atmospheric changes.
Even so called reduced creep PVA's still move sufficiently to suffer from this, no problem with normal cabinet making but becomes frustrating with contiguous surface joints.

It's for this reason I use Cascamite for any joints that are going to be at risk of this as it sets brittle hard and does not move, something that looks like being a real niggle for me now that Cascamite is going through a production problems.


If your items have stabilised somewhat in their intended environment you may improve things by re-sanding and finishing.

Ok, so I've re-sanded and refinished it - I'll see what happens to it.

I've ordered a small pot of that Cascamite to see if that helps with the next one. What production problems are they having, just volume or are they changing their formula?

.
 

CHJ

Established Member
Joined
31 Dec 2004
Messages
20,103
Reaction score
45
Location
Cotswolds UK
ScaredyCat":378to4zr said:
.....

I've ordered a small pot of that Cascamite to see if that helps with the next one. What production problems are they having, just volume or are they changing their formula?

.
cascamite-glue-t121552.html

topic119745.html

When you mixed the original formula Cascamite to correct proportions you ended up with a very smooth, runny honey consistency. If it had a gritty look & feel to it, it was an indication that it had been subject to atmospheric moisture contamination and was scrap.

Hence the discomfort with some batches of the newer formulas that are not mixing or behaving the same as the original to the point folks are not sure they can trust it.
 
Top