Veneering advise

[Will123]

Have a project on the go that requires a 3.6metre run of 8 kitchen doors to be veneered for a horizontal grain match. I've ordered some european oak veneer leafs 1.5mm thick 3.8long that we will joint on panel saw, my question is would we be able to veneer one side of 19mm oak veneered mdf without the board curling/cupping? This would save having to veneer both sides of the substrate board. If so what glue would be most suitable (we have a vacuum press)

TIA

 

[Mike.R]

You must veneer both sides of the panels to avoid cupping.
I would use PVA as an adhesive.
I.5 mm thick oak seems excessive for decorative veneering.
Sounds like a great project, please post pictures when you're done.

 

[user 40558]

Totally agree with @Mike.R - you will need to veneer both sides of the board to minimise chances of cupping. And I've always had best results if the balancer veneer is the exact same as the face veneer, rather than a different thickness/species/direction etc
On choice of glue PVA could work fine, but you may get a bit of bleedthrough if there is any short grain in the veneer. On open-grained veneers we tend to use a UF resin glue that we can add extenders to to limit bleed. There are many of these to choose from - Airpress sell one we use a bit, also Adkwik if you're feeling flush with cash...

 

[Will123]

You must veneer both sides of the panels to avoid cupping.
I would use PVA as an adhesive.
I.5 mm thick oak seems excessive for decorative veneering.
Sounds like a great project, please post pictures when you're done.

Thanks for the advice. First time that I've tried any veneering other than paper backed veneer. Thought 1.5mm would be easier to work with than say .6mm but probably wrong.

 

[Will123]

Totally agree with @Mike.R - you will need to veneer both sides of the board to minimise chances of cupping. And I've always had best results if the balancer veneer is the exact same as the face veneer, rather than a different thickness/species/direction etc
On choice of glue PVA could work fine, but you may get a bit of bleedthrough if there is any short grain in the veneer. On open-grained veneers we tend to use a UF resin glue that we can add extenders to to limit bleed. There are many of these to choose from - Airpress sell one we use a bit, also Adkwik if you're feeling flush with cash...

Thanks, will do the backs first as a trial run then!

 

[Sgian Dubh]

Have a project on the go that requires a 3.6metre run of 8 kitchen doors to be veneered for a horizontal grain match. I've ordered some european oak veneer leafs 1.5mm thick 3.8long that we will joint on panel saw, my question is would we be able to veneer one side of 19mm oak veneered mdf without the board curling/cupping? This would save having to veneer both sides of the substrate board. If so what glue would be most suitable (we have a vacuum press)

TIA

As you have a vac press rather than a vac bag it's relatively easy to veneer both faces of the ground at the same time, so I can't see any good reason not to do so. That would minimise the chance of the panels developing warpage due to imbalance. It would also save time because you veneer two faces per pressing. All you need is something like an MFC base board with a series of narrow and shallow slits that just penetrate the melamine face upon which you lay a sheet of veneer. Then apply glue with a hopper type roller to the ground and drop that on the veneer. Glue the other side of the ground, lay the other sheet of veneer on to that, put a protective piece of slitted MFC on top (to protect the exposed edge of the overhanging veneer), drop and lock the folding top and switch on. The slits in the MFC boards, in case you don't know, are to encourage air movement during creating the vacuum.

As to adhesive, assuming little or no contact with water, a PVA type should work fine, although Titebond, for example have a cold press for veneer formulation which has a somewhat extended open time which can be useful. Airpress in Salisbury also sell adhesive spreaders, veneer friendly adhesives as well as vac bags and presses. Slainte.

 

[Will123]

As you have a vac press rather than a vac bag it's relatively easy to veneer both faces of the ground at the same time, so I can't see any good reason not to do so. That would minimise the chance of the panels developing warpage due to imbalance. It would also save time because you veneer two faces per pressing. All you need is something like an MFC base board with a series of narrow and shallow slits that just penetrate the melamine face upon which you lay a sheet of veneer. Then apply glue with a hopper type roller to the ground and drop that on the veneer. Glue the other side of the ground, lay the other sheet of veneer on to that, put a protective piece of slitted MFC on top (to protect the exposed edge of the overhanging veneer), drop and lock the folding top and switch on. The slits in the MFC boards, in case you don't know, are to encourage air movement during creating the vacuum.

As to adhesive, assuming little or no contact with water, a PVA type should work fine, although Titebond, for example have a cold press for veneer formulation which has a somewhat extended open time which can be useful. Airpress in Salisbury also sell adhesive spreaders, veneer friendly adhesives as well as vac bags and presses. Slainte.

Thanks will look at the titebond. It is a bag we have not a press.

 

[Hornbeam]

I would just use standard thickness veneer on both sides. If vac bagging you must use pressure boards top and bottom otherwise you can get very slight wrinkling/rippling of the veneer, particularly if you were a but generous with the glue. Veneering both sides at once is best particularly if there as 2 of you working on it. Prefer UF as you have more time to work with it and it is waterproof so better in a kitchen
If you want to use the 1.5mm I would lay everything out cut to size and then edge joint the veneers prior to laying. Also thing about what thickness you want the finished doors to be, anything over about 19mm seems a bit clunky. If you want the grain to run right through all the doors you may want to lip everything before veneering which I think would work OK with 1.5mm veneers

 

[Reffc]

I’d echo the comments above. Standard pulp or paper backed 0.6mm would be fine. I would caution against titebond cold press having just tried it. As it doesnt sell strongly nor has a manufacture or use by stamped on it you risk buying old stock as happened to me. It had stiff lumps in the bottom of the jug which were impossible to stir back into solution so I had to junk it. Had a 1m panel to vacuum veneer and used Everbuild 502 D3 pva which worked fine. Roller applied in a thin coat to both substrait and veneer and popped into the bad for 40 minutes. Temperature in workshop was 13 or 14 degrees so open time was more extended.

 

[Droogs]

UF will defo give you some breathing space as you set up . Personally I would use plattens ~20mm over size all round for top and bottom covered in cling film. I would also tooth the veneer as this will give a much better key for the glue and as it spreads during pressing to help avoid voids afterwards. As you are using a fairly thick & large slice it would be advisable to give it a going over with a reviver mix a couple of days before, it's amazing how it helps prevent splits and cracks. Also have mesh above & below the outside of the plattens to assist in preventing wrinkles in the bag as you draw the air out.

 

[TRITON]

Thanks for the advice. First time that I've tried any veneering other than paper backed veneer. Thought 1.5mm would be easier to work with than say .6mm but probably wrong.

Naw not at all. 1.5mm will give you plenty of scope for sanding, and will likely lay better without undulations or such. Veneer used to be the thick stuff until those profit hungry big businesses took over.
Plus on the counter veneer, that needs to be placed the opposite way, as in the grain horizontal to a vertical front veneer(or however the front is orientated.

 

[Sgian Dubh]

Plus on the counter veneer, that needs to be placed the opposite way, as in the grain horizontal to a vertical front veneer(or however the front is orientated.

Are you sure about that?

That seems to be saying that the two outer veneers of a sheet of plywood should be set at 90º to each other, which is never (as far as I'm aware) how such boards are manufactured: the two outer skins have their long grain orientation set parallel. The same grain orientation convention applies to veneered MDF and chipboard panels.

Maybe I misunderstood your suggestion. Slainte.

 

[recipio]

No experience with UF glue so I can only comment of the Titebond Cold Press. I'd say the open time is 20 - 25 mins so you need to have everything ready to go. Avoid too much glue at all costs so I'd suggest a short nap roller if you don't have a hopper type . The ambient air temperature must be above 6 C . The Titebond doesn't drip as much as the other PVA's and thankfully any bleed through sands off without any staining. I've imported the paper backed veneers from Oakwood Veneers in the US ( the vast range probably justifies the expense ) and they advise either PVA or a gel type contact adhesive. However for regular veneer I think I'd stick with PVA.

 

[TRITON]

Er ok. thats exactly what ive said. counteracting veneer is 90 degrees to the other side veneer.

Think plywood. for bendy ply the grain of each sheer orientates the same direction. This allows it to bend easily
For regular plywood, each alternate sheet is at right angles to the previous one.
If you put a single sheet of grain orientated veneer on your door, it will want to cup. Place a piece on the back in the same orientation its not going to counter act, but extenuate the cupping.

This is why if you veneer your door with the grain going up and down, the counteracting sheet must be at right angles to it to prevent it from cupping.

This is the way i was taught to veneer.

 

[Hornbeam]

This ius why if you veneer your door with the grain going up and down, the counteracting sheet must be at right angles to it to prevent it from cupping.

No this is not correct
If you look at plywood it is always symmetrical
If you apply veneer to one face of a substrate (mdf/plywood etc) the backing veneer should be of similar thickness and the grain should run in the same direction as the face veneer. This maintains symmetry and keeps any forces from expansion/contraction of teh outer sheets in balance. Where it can get a bit more subjective is if you were using a highly figured burr veneer where it can be difficult to tell where the grain is running
Ian

 

[XTiffy]

I don't know where you are but I have had very complex veneer work (Mahogany curl veneers with crossbanding etc.) and have used professional veneer workshops. They have all of the equipment (including heated presses and v.large guillotines) and I have never found them expensive compared to the chance of spoiling fine veneers. Completely agree with others here 1.2mm veneer is overkill! Your biggest problem is protecting the edges. I have never used backing veneer at 90 degrees to the front and never had cupping, frankly I think it would look wrong, after all you are trying to make it look solid!

 

[TRITON]

I may be wrong in this its been a long time since ive done any veneering, and mostly work in solid timber.

 

[Sgian Dubh]

I may be wrong in this its been a long time since ive done any veneering, and mostly work in solid timber.

I didn't want to say it before because I thought I might have misunderstood you but, I'd say your first sentence in the quotation above is also not quite right. I think you are simply wrong.

As to bendy (flexible) ply, it doesn't always have all the layers assembled with their grain running parallel. Much of it, probably the great majority, is composed of two thicker outer layers, treated to make them soft, with their long grain running parallel to each other, and a thin central layer set at right angles to those two outer layers, see below for an example. Slainte.

 

[Droogs]

I think @TRITON just hasn't put it very well. He perhaps meant that the sheet of veneer should be place at 90 degees to the background grain it is being glued to on both the front and the back. Properly veneered boards should always have an odd number of layers to ensure even stresses that counter act each other, also on particularly thin panels particular attention should be given to ensuring that the correct face of the veneer is showing (ie the side without the small stress shakes from the cutting knife when it was sliced.) Otherwise you end up with the stress etc all going in the same direction and find a banana board waiting for you in the morning.