PDA

View Full Version : laying large veneer



mongrell
15th February 2007, 05:30 PM
have a piece of veneer 44 inches by 15 to lay its got sorta bubbles all over it and wont lay flat . having never done any veneer work before need a bit of advice here , how to get it flat ,glu etc :?

Ray153
15th February 2007, 06:49 PM
Mong, I have read that the optimal method is to wet down the veneer with a mix of water and possibly glycerine til it is pliable. Then get a couple of newspapers and place your veneer between the two papers. Think of this process as type of sandwich. The veneer is the filling, the newspaper is the margarine and the sheets of MDF on the outside of the paper are the bread. You want the MDF to be the same size as the veneer or slightly oversize. Weight the MDF with something reasonably weighty and change out the papers every day till the veneer is dry. This apparently will work although I haven't tried it myself so will be only too happy to hear other ideas.
Once it is dry and flat, you can then use it in a project. If you are just veneering a flat sheet, yellow PVA works well for me. I use 6 mm ply and it is advisable to lay the grain of the veneer at 90 degrees to the top grain of the ply. This way the veneer effectively becomes another ply in the sheet. I have a cheap but very effecitive vacuum kit that I use for veneering, so it is pretty straight forward. MDF 19 mm sheet, veneer project on top then another MDF sheet and slide the whole lot into the vacuum bag. I have MDF sheets with clear contact on the inner face in case of any glue seepage.
Don't forget to veneer both sides of the ply sheet or it will cup. If the obverse side is not going to show, then use a more common sheet of veneer, I wouldn't be sacrificing a prize piece of walnut or huon on a side that will never see the light of day.

chrisb691
15th February 2007, 09:36 PM
Mong, I have read that the optimal method is to wet down the veneer with a mix of water and possibly glycerine til it is pliable. Then get a couple of newspapers and place your veneer between the two papers. Think of this process as type of sandwich. The veneer is the filling, the newspaper is the margarine and the sheets of MDF on the outside of the paper are the bread. You want the MDF to be the same size as the veneer or slightly oversize. Weight the MDF with something reasonably weighty and change out the papers every day till the veneer is dry. This apparently will work although I haven't tried it myself so will be only too happy to hear other ideas.


This I how we flatten smaller pieces, for use in marquetry. I see no reason why the process shouldn't scale up But, don't use newspaper in direct contact with the veneer, as the ink might/will leach into the veneer. Use plain white paper in contact with the veneer, with your newspaper on top of that.

martrix
15th February 2007, 09:41 PM
How to flatten excessively curly or wavy veneer. (http://members.cox.net/ampage/veneerflat.htm):wink:

Cabbie
15th February 2007, 11:29 PM
Mong, Don't forget to veneer both sides of the ply sheet or it will cup.

If you want only one side veneered to stop it cupping groove the board about 0.5mm (0.02") or less deep at around 100mm (3.95") spacings on the side you want to veneer. Don't groove it to deep or it will show up in the veneer. This stops the board from cupping or at least reduces it. It is a method I have used quite often especially on melamine doors when I laminate them.

martrix
15th February 2007, 11:35 PM
If you want only one side veneered to stop it cupping groove the board about 0.5mm (0.02") or less deep at around 100mm (3.95") spacings on the side you want to veneer. Don't groove it to deep or it will show up in the veneer. This stops the board from cupping or at least reduces it. It is a method I have used quite often especially on melamine doors when I laminate them.

Hi Cabbie, are you talking about using 1.5mm veneer ply?
I think mong is talking about using 0.6mm raw veneer and any grooves in the gluing face I think would be asking for problems.

Lignum
16th February 2007, 12:00 AM
And dont forget to veneer the "right" side of the veneer.

When veneer is sliced (like a plane taking shavings) the side (underneath) that comes into contact with the blade is sliced cleanly and the top lifts and is "fractured." Thats why a leaf curls up, But that top should be the underside when you veneer because when its polished their is a big difference in the depth and sheen of the grain (one side smooth and the other broken) Doing that then brings into question the debate over bookmatching V slipmatching. Im a Slipmatcher:wink:

Lignum
16th February 2007, 12:05 AM
I think mong is talking about using 0.6mm raw veneer and any grooves in the gluing face I think would be asking for problems.

Martrix, you mean to say you have never put a 0.2mm groove in a 0.6 veneer leaf before:?

Cabbie
16th February 2007, 12:50 PM
I am not talking about putting it in the veneer I am talking about putting it in the board. I am talking about veneers with a thickness of around 0.6-0.8mm and I have never had any problems with glueing it. You have to remember that you can't go too deep though or you will run into problems. That is why I suggest going to a depth of 0.5mm or less I usually try 0.2mm but sometimes it wont always groove right through. If you go too deep you will get problems.

martrix
16th February 2007, 01:27 PM
I am not talking about putting it in the veneer I am talking about putting it in the board. I am talking about veneers with a thickness of around 0.6-0.8mm and I have never had any problems with glueing it. You have to remember that you can't go too deep though or you will run into problems. That is why I suggest going to a depth of 0.5mm or less I usually try 0.2mm but sometimes it wont always groove right through. If you go too deep you will get problems.
Hi Cabbie, yes I understand that you mean putting grooves in the face of the board, and then gluing the veneer over the grooves.

When you have done this, what glue did you use?

Lignum
16th February 2007, 01:52 PM
If you want only one side veneered to stop it cupping groove the board about 0.5mm (0.02") or less deep at around 100mm (3.95") spacings on the side you want to veneer. Don't groove it to deep or it will show up in the veneer. This stops the board from cupping or at least reduces it. It is a method I have used quite often especially on melamine doors when I laminate them.

Cabbie, have you tryed this with veneer? or just melamine. I would never do this with veneer (unless you want immitation fiddleback:rolleyes:) It would be a recipe for desaster. If it is the only alternative you would need to use epoxy or urea to fill the grooves.

mongrell
16th February 2007, 06:59 PM
thanks for all the replies i think i get trhe message ,one last question ,im gluing onto 14 mill mdf do i still need to do both sides ?

Lignum
16th February 2007, 07:13 PM
thanks for all the replies i think i get trhe message ,one last question ,im gluing onto 14 mill mdf do i still need to do both sides ?


Yes. But a 2nd grade backing veneer is all you will need. But you must do both sides:)

Wild Dingo
16th February 2007, 11:46 PM
To straighten use Martrix's linked method... it works :2tsup:

Wet the FACING side (the side that will show) with a fine mist spray of just water FIRST then flip it over... make up a mix of yellow glue and water to dilute it then spread (paint) the diluted glue over the underside (non facing) of the veneer and glue it down to the substate... the glue does not need to be full stregth glue... diluted gives you more time and an easier glueup... the other side of the substrate mdf ply whatever must have a veneer surface added to equal out the moisture and stop cupping do the same as the facing side using offcuts or poor quality veneers... just make sure the whole back surface is covered with veneer the same as the show/facing side

I do them at the same time its not difficult do the underside FIRST then do the Facing side that way you can take more time and care with the facing side to get it right

Make the sheets overlap the edges by 1/4 to 1/2in all round... cut this back when its finished glueup

Have EVERYTHING ready BEFORE you begin... clamps glue spray bottle veneers for both sides clamping boards and whatever else your going to use get them ready and to hand... you are going to want to move once you have it right and ready... dont leave the clamps on the bench on the other side of the shed thinking you will have shyteloads of time YOU WONT have them to hand.

DO NOT use newspaper the ink WILL leach through use white paper butchers paper the end of newprint rolls (go to your local community newspaper and ask if they have any "end of run rolls" usually they will give them away free and they will have quite a bit of paper still usable) its thin it rips easy but it works with veneer.

I find it goes easy as if your organized the only time its gone assup is when I wasnt :doh:

USE LOTS OF CLAMPS!! CLAMPS ARE YOUR FRIEND :2tsup: :2tsup:

Hope this helps :;

ooh and if your going the vacumm bag method... I cant help and much of what I just posted may well be next to useless since Ive not done any veneering that way

Good luck

Cabbie
19th February 2007, 01:02 AM
Cabbie, have you tryed this with veneer? or just melamine. I would never do this with veneer (unless you want immitation fiddleback:rolleyes:) It would be a recipe for desaster. If it is the only alternative you would need to use epoxy or urea to fill the grooves.


I usually use contact. You have to be careful using contact though when you go to put the lacquer on, if you spray it too heavy, it will sometimes seep through and the contact will dissolve letting the veneer bubble. I find just putting a few light coats on and filling the grain, rub it back a little then apply the heavier coats, depending on the finish, will work. I only ever use PVA when I have access to a vacuum press although I do like the idea of using a vacuum bag. Never thought of doing that before and I may give that a go to see how that works. I have never had a problem with the grooves never had them showing up at all on the face side at all and it has always stuck well when I have done it. On another tangent though I once had a curved counter that had the face panel kerfed on a CNC. It was a high gloss purple finish and instead of it coming out as a smooth flat surface it came out with a lot of small evenly spaced 20mm flat edges which wasn't what was supposed to be the outcome wanted but the client loved the look and kept it. Sorry it had nothing to do with veneering but I just thought I'd throw it in. ;)

mongrell
13th March 2007, 08:46 PM
thanks for all the replies have gone for the glycerine and water and weight theory . last time i looked it had prolly flattened 50 percent this time ill leave the weight on for 10 days or so and hopefully should be ok to lay the veneer