I recently had a humidity issue in my shop during a really cold spell. It caused a back that I had braced up to flatten and even curl up on the edges where I had scalloped the braces. so i chisel, planed and thickness sanded all the bracing and center stip off. in the process of doing that the back became too thin. so now I'm going to laminate the back in order to save the really nice back of bog oak.
question is now the back is 1.75 mm thick. was going to laminate a section of Spanish Cedar and another piece of bog oak veneer to the inside. each of those being .5mm. will i have any issues having with 3 layers and the 2 inside lams being a different thickness? I could thickness the outside layer down to 1.1mm and also the inside lam down to 1.1mm and then have the inside lam be .5mm so would end up with 2.7mm back.
also, do you need to brace a laminated back the same way you would a solid wood back?
i will be vacuum pressing in my radius dish using west sys epoxy.
thanks
sean
Hi Sean,
ideally you should have lay up that is symmetrical so that the glue lines are equally spaced on, and on either side of the centre line (of the thickness). I have used West System for the first sides I laminated but never again! You will get so much bleed through it will take you an age to clean up, especially with a veneer as open grained as oak. I would suggest the UF resin system that I use but I’m out of stock of the resin at the moment. I would use Titebond rather than West System but obviously the choice is yours. Whichever route you take just make sure that you put a layer of polythene on your radius dish or you will have another problem on your hands!
Cheers
Darren
@darrenking thanks for the response. i am in US and googled UF resin system but its all technical articles. i guess it's also called plastic resin glue.
i will take both inside and outside lams to the same thickness.
do you brace the back the same as a solid wood back?
Hi Sean,
UF = Urea Formaldehyde
It’s available as a liquid resin/powder hardener, liquid resin/liquid hardener and also a one shot powder that you add water to. One of the main benefits is that you can also mixed in a filler, or extender, powder which helps prevent bleed through to the point where it just isn’t a problem. It also has quite a long cure time of 4-8 hours so the layers of veneer have plenty of time to squeeze together and the adhesive squish into the grain before any cure starts to happen.
I’m not sure what the availability of UF resin systems is like in the US but you could also check manufacturers such as Dynea and brand names such as Extramite, Cascamite, Aerolite. Avoid Marmite though, it’s not everyone’s bag and some people really hate it! 🤣🤣🤣
Yes, I would use the same bracing pattern as for a solid back and if you need to use 4 layers of veneer that will be fine. You can choose to have them all with the grain running in the same direction or have the central ones at 90 degrees to increase temperature/humidity stability and rigidity.
Darren
Good luck
Darren
@darrenking thanks again. i'm going to use 3 layers.
i found this. is this it?
did find aerolite but its all in the UK and europe.