Thread: Best finish fro thin veneers?

Hi Dengue
I have used the wipe-on poly finish on veneer and looks quite nice.
Have also in the past used french polish but it is long winded and not durable,sparay finishes also work well if you have the facilities to do it.

If you are very careful you an use an ROS sander for larger projects but you need to take great care near the edges and wouldn't use anything coarser than 240 grit to start out.
May be safer to rub down by hand as this was all I had available 30 years ago when I started using veneer.
You can wrap abrasive sheet around a block of Mdf,I wouldnt trust cork sanding block or anything similar as you probably end up with an uneven surfce.

I have done some recent veneering with West systems epoxy and vacuum bag and was impressed with the results.

Hi Dengue,

I guess it all depends on the degree of unevenness. If the veneer is too uneven it may crack and split as you clamp it to the substrate. Wetting and warming the veneer is often used to make it pliable. You could soak it in hot water until it is flexible or wet the veneer and use a household iron warm the sheet. The pliable veneer is then clamped with absorbent paper either side between two flat cauls. The paper is changed a couple of times a day at first, then daily until the veneer is dry.

Since you are using a epoxy glue I'd opt for polyurethane varnish. I'm unaware of any incompatibility between epoxy and poly.

It is common practice to veneer both sides of the ply substrate.

Hello again Dengue,

I do not know your reason for using epoxy as an adhesive. Perhaps your box has to be water resistant.

Any way, I learned my veneering skills from watching Barry Lorimer on YouTube. He uses hide glue. Worth a watch if you're just getting into veneer.

Originally Posted by Dengue

Q.2. I imagine it will be pretty risky sanding such thin material.

I always sand delicate veneers with a drum sander. It might sound rough, but if you can work out what percentage of a handwheel turn represents a 0.05 mm advance, then passing it through the drum sander 4 times means no part of the veneer can be less then 0.40mm thick.

That's still a long way from sanding through, even on the most translucent timbers.

I think about 1/12 of a full turn is about 0.05mm (on my machine).

If the workpiece is a bit wobbly I put masking tape underneath where the low spots are.

If any bits are still missed I get them with a ROS.

The drum sander has either 180 or 240 grit. The ROS has 240. That's fine enough if you are using a high-build finish (pre-cat spray lacquer in my case).

Then spray NC sealer.
Then grain fill and/or gap fill.
Then sand with 400 grit on a ROS - sealer takes just the lightest possible sanding to be baby smooth. Any tricky bits I do with a detail sander or (reluctantly) sand by hand.
Then spray top coats.
Leave a few days.
Sand any dust nibs with 1500 and then buff till it has a mellow shine.

cheers
Arron

personally I have never bothered with any kind of surface prep for veneers other than flattening buckled veneers.
Your choice of epoxy is ideal,I learnt about using hide glue over 25 years ago but is rather messy and smelly and ideally you need a double walled glue pot and veneer hammer and probably your wife's best clothes iron.
Hammer veneering the old fashioned way is good skill to learn but not really of any great importance these days except for antique restoration.
Given your climate in Townsville I suspect the lack of stability of hide glue made be a problem especially as you get a lot of humiditiy

I forgot a step.
After it comes out of the press I often need to daub it with dilute deck cleaner. Especially useful in your climate where mould has a big head start.

If there is any mould or other discolouration on the veneer it's better to get it out with deck cleaner then try to sand it out.

Originally Posted by mark david

personally I have never bothered with any kind of surface prep for veneers other than flattening buckled veneers.
Your choice of epoxy is ideal,I learnt about using hide glue over 25 years ago but is rather messy and smelly and ideally you need a double walled glue pot and veneer hammer and probably your wife's best clothes iron.
Hammer veneering the old fashioned way is good skill to learn but not really of any great importance these days except for antique restoration.
Given your climate in Townsville I suspect the lack of stability of hide glue made be a problem especially as you get a lot of humiditiy

This is what is so endearing about woodwork: There are numerous techniques by which to reach the end result. Find the technique that works in your situation and that with which you are comfortable and happy to perform and you have a great hobby.

Well, based on the above valuable posts, I ran the 400 x 250mm veneered lid panel through a drum sander very carefully and got rid of the scratches and sawblade marks - goodness know where they came from , it was like the veneers were ripped with a big circular sawblade on a table saw.

I then decided to sand the veneer to 600 grit using wet and dry sandpaper, starting at 240, then 320, 400 and then 600 grits.

I was not confident enough to use a ROS and land it dead flat each time, especially with only 0.6mm thickness of veneer, so I cut some sheets 280 x 105 and attached them to a sanding float similar to what you see below.

I then dipped the float and W&D 240 grit sandpaper in a bucket of luke warm water with a few squirts of dish washing liquid added, and with the workpiece lying in a tray sanded the veneered workpiece very lightly. There was a lot of water involved. The result was the workpiece was saturated both sides. Indeed, if I had used PVA or yellow glue to bond the veneer sheet to the plywood substrate, the veneer would have separated. A real benefit of using epoxy !! As it was, I was lucky the joins on the sheets did not show up - whew!!

I then washed the remaining soapy liquid from both sides of the workpiece under a tap, wiped them down with a rag, wrapped them in some butchers paper and put them between a couple of melamine cauls and added some weights. I took it out 1/2 hour later and let it dry naturally in an upright position. Unfortunately the workpiece is not as flat as it was prior to this sanding.

I suppose the next step is to let it dry overnight and repeat the process with 320 grit

I am sure there must be a better way of doing this, and would appreciate any suggestions or criticisms

float.jpg

This might be just my opinion but I would not bring a veneered panel within a million miles of my drum sander,I think it is just too risky and you can sand throught the thin veneer in a heartbeat.It is possible to get some minor sniping which would be disastrous to veneer.
I used to sand all my veneered work by hand but now use the Festool ROS being especially careful at the edges and taking the sanding disc no more than 1/3 of its diameter over the edge and using grit no coarser than 240.

Tempting fate - after a few hours the veneered plywood workpiece seemed dry, so this time I just spritzed the surface of the veneer with a light spray of water from a plant mister. The result was a lot less water, and the W&D formed a sort of slurry with the sawdust removed after a couple of passes with the next higher grit of the float sander, so stopped immediately.

I then wiped the board down with wet then dry rags, sanded the other side in the same manner, then wrapped in butchers paper and put between melamine cauls and weighed it down for 30 minutes.

Will let it dry overnight.

Tempted to use the 400 grit just dry tomorrow, no water, to see what happens

Originally Posted by Dengue

Tempting fate - after a few hours the veneered plywood workpiece seemed dry, so this time I just spritzed the surface of the veneer with a light spray of water from a plant mister. The result was a lot less water, and the W&D formed a sort of slurry with the sawdust removed after a couple of passes with the next higher grit of the float sander, so stopped immediately.

I then wiped the board down with wet then dry rags, sanded the other side in the same manner, then wrapped in butchers paper and put between melamine cauls and weighed it down for 30 minutes.

Will let it dry overnight.

Tempted to use the 400 grit just dry tomorrow, no water, to see what happens

Hi Dengue,I would not recommend any kind of wet sanding of veneer,I haven't ever tried this and the thought of doing it has never entered my mind.
I also do not recommend veneering of plywood as you can never be sure that the top layer of ply is 100% securely glued to the layer underneath,such is the quality of ply these days.MDF in my opinion is one of the best carcase materials for veneering.
If you do veneer on plywood then veneer with the grain at 90 degrees.

Hi Dengue,

I have had good success when I have used such thin veneer that was quite uneven - fiddle-back Blackwood - and I used veneer softener (https://www.carbatec.com.au/embellis...er-softener)to relax the fibres before vacuum pressing it onto plywood (good quality face Hoop Pine ply). I used polyurethane adhesive (Purbond). There was no sanding required afterwards though I did have to use a cabinet scraper where some of the polyurethane bled through a split. One time I used an expensive vacuum pump system (at a professional workshop) but have since used the much less expensive hand-pump system at home (https://www.carbatec.com.au/clamping...r-press-kit-26).

Originally Posted by mark david

This might be just my opinion but I would not bring a veneered panel within a million miles of my drum sander,I think it is just too risky and you can sand throught the thin veneer in a heartbeat.It is possible to get some minor sniping which would be disastrous to veneer.
I used to sand all my veneered work by hand but now use the Festool ROS being especially careful at the edges and taking the sanding disc no more than 1/3 of its diameter over the edge and using grit no coarser than 240.

Yeah, I guess I should have elaborated a bit more:
Keep two hands on the workpiece whenever possible - keeping it flat and stopping any edge rising up. Keep forward pressure on it with your hands to stop the workpiece stalling or slipping. Use a long piece of 3mm ply with a handle on the end as a push stick as the trailing edge approaches the nearside roller and keep pushing firmly until it comes out the other end rather then relying on the machine to keep it moving.

In other words guide it through dont just drop it in and trust the machine.

If the workpiece can't tilt and the roller isn't allowed to dwell at any point then you won't have a problem. Just feeding it in and letting the machine do the work will very likely end in tears.

Hi Dengue, Next time you have a veneer project and since you have used Kunos before, what I would suggest is apply a coat of the oil, wipe off after 5 minutes. This will not allow the oil wax resin to penetrate as far as if left for e.g. 20 minutes. This "blocks" the pores at that level without getting any deeper that with very thin veneers may cause issues with the glue. Apply subsequent coats as normal.