purple heart chopping board joints failing

[navypaul]

hi
i have a sang that is bothering me i have recently made a end grain purple heart chopping board and it seems that some outboard joints are coming apart. i have made other boards so i am hoping its just the wood and not what im doing.

anyone else experienced this?
regards
paul

 

[tomasg]

When you glued up your pieces were they freshly planed ?....
Best practice with oily woods is to glue quickly before the oils come to the surface
especially problematic with cocobolo
Ive heard of people wiping alcohol on surfaces
Interested to know what glue your using
tom

 

[jamesevenlode]

I build guitars, not chopping boards, but I strip the oils off rosewood, cocobolo and such with acetone before gluing.
Sometimes a piece is so oily I can't use Titebond.
I use epoxy in that situation.

 

[Beau]

Yes I also use acetone shortly before glueing up with oil woods.

 

[tomasg]

I went back to the OLF forum and checked to see if i remembered correctly
I doubted myself as the consensus seems to be acetone mostly but
I did find a reference to denatured alcohol after a doing a quick search .
Some say that it keeps bleeding even after its been wiped over and over
and as the acetone penetrates deeper it will constantly keep leeching more oils out
The most recent posts are in favor of gluing freshly cut surfaces without .
These guys all keep a stable relative humidity in their shops
Don't know if that would make things more problematic though

 

[Kalimna]

Yep, the received wisdom on the MIMF luthiery forum is that use of a solvent on oily timbers is not as useful as it should, in theory, be. They generally recommend gluing on freshly planed surfaces only. With epoxy reserved for particularly nasty wood.

Adam

 

[n0legs]

Is purple heart food safe?
I'm sure I read someone here has an allergy to/from it.

 

[navypaul]

thanks for the reply

i did not glue it directly after machining which i will do next time i used titebond 3 or 2 cant remember which one. on the wood allergy and toxicity site PH is rated similar to oak.

paul

 

[navypaul]

spoke to the guy who owns mtm they make chopping boards and the like (they're all over youtube) and he states the same that it should be glued before an hour is up, but this bloody stuff just wont glue. I glued it with in 20 mins from freshly planed side to side grain and it still didnt take well, think i need something stronger than titebond but still food safe.

 

[custard]

As long as your glue is in date code and has never been frozen in an unheated shed, then could it be the accuracy of your stock preparation or your technique?

I don't know how experienced you are, so don't take this the wrong way if you've actually got half a dozen Guild Marks and trained with John Makepeace! But if you're gluing up a complete end grain chopping board in one go then that's not as straightforward as it might at first seem. Each component would need to be freshly machined and square to engineering standards (if you leave any component for more than a few hours it'll probably move minutely, not much but enough to introduce gaps that PVA can't fill), the clamping would require precisely made cauls, and if you're using PVA you'd have to go like the wind to get it all assembled within the open time.

You might be better off with a gap filling adhesive like Cascamite or Epoxy, both of which have the added benefit that they don't require quite such high clamping pressures..

 

[navypaul]

i didnt think it was possible to glue up all those blocks in one go. i do it like everyone else does in strips

i dont think cascamite is food safe and in certain epoxy is not. i know that when glues cure they are meant to become inert but i would not use it in any food prep utensil. i do use cascamite on other things like tables and such not because it fills gaps but because it is a strong glue.