A simple finish to start with...

[Cloth Ears]

Hi,

I'm starting my first project that actually uses a wood veneer finish (instead of paint) and I'd like to start simply. The actual project is a simple speaker, an open baffle type - which simply means a single slab of MDF, held up by a brace. The brace is going to be painted gloss black (not to piano standards, but quire nice) and the front and back of the 25mm MDF is going to be veneered.

I've found a fellow who can supply some raw veneer in thicknesses that I should be able to handle. And I was planning on using a simple glue (rather than a contact) and pressure to attach the veneer to the slab.

Is this a good plan? And, what is a good way to finish it? I don't mind spending some time on it, but I was looking more towards a shellac/varnish rather than an oil finish. The wood type for the veneer hasn't been chosen yet, but it'll be a blond-ish wood with not too much grain definition (I want to start a bit cheaply so that I don't dry if I have to redo the whole thing).

Pointers to threads that deal with this would be very welcome. I've read a few that muched my searching, but they didn't quite answer the question (I may not have put it very well here, either).

[jerryc]

First is attaching veneer. Using contact adhesive is a real no no. Contact is very liable to creep over time and can open up gaps. I assume you mean veneer in the real sense, that is a thin fragile sheet. Best method is to use cross linked PVA glue. Selley's tradesman's choice is a good example. My instructions might be over simplified but you can PM me for more help.
To apply veneer, paint a thinned coat of PVA on both the ground (base) and on one side of the veneer. You will find one side is usually smoother, that would be your finish surface. make sure you don't develop puddles of glue. A gentle sanding just to remove the nibs then take an iron set to linen and gently iron the veneer down. starting from the centre outwards to avoid air bubbles

As to finish with shellac, there is a great deal of info including a post from me on the correct way to make a rubber. Wiping shellac is by far the easiest way to apply it. Shellac properly applied dries fast enough for you to get several coats on in a very short time. As to whether you would need to varnish after applying shellac, that depends a lot on the type of treatment you expect the speaker will be subjected to. My own advice is shellac would be good enough in it's own right. I have used it in quite harsh conditions. I know some others here will disagree so listen to everyone and make up your own mind.

Just ask questions if you are unsure.

Jerry

War does not decide who is right. War only decides who is left

[Cloth Ears]

First is attaching veneer. Using contact adhesive is a real no no. Contact is very liable to creep over time and can open up gaps. I assume you mean veneer in the real sense, that is a thin fragile sheet. Best method is to use cross linked PVA glue. Selley's tradesman's choice is a good example. My instructions might be over simplified but you can PM me for more help.
To apply veneer, paint a thinned coat of PVA on both the ground (base) and on one side of the veneer. You will find one side is usually smoother, that would be your finish surface. make sure you don't develop puddles of glue. A gentle sanding just to remove the nibs then take an iron set to linen and gently iron the veneer down. starting from the centre outwards to avoid air bubbles

As to finish with shellac, there is a great deal of info including a post from me on the correct way to make a rubber. Wiping shellac is by far the easiest way to apply it. Shellac properly applied dries fast enough for you to get several coats on in a very short time. As to whether you would need to varnish after applying shellac, that depends a lot on the type of treatment you expect the speaker will be subjected to. My own advice is shellac would be good enough in it's own right. I have used it in quite harsh conditions. I know some others here will disagree so listen to everyone and make up your own mind.

Jerry,

Thank you. Now questions...

Starting from the end, the rubber post you mentioned is this one...Shellac, tell me all you know? And I assume the rest of the thread is just as useful (if occasionally differing in viewpoints)?
If I start with a small pot of pre-mix shellac, will I still be allowed to post?
And, you said a 'thinned' coat of the PVA - did you mean 'thin'? Or, what do I thin it with, please?
And lastly, the iron - these are serious questions for me. I assume it's to be on the highest temperature, correct? And the iron is used on the veneer surface directly - does this not singe any of the lighter woods? Does the heat activate the PVA, and if so, does another application of heat cause it to reactivate (hot coffee cup or somesuch)?

[jerryc]

Cloth Ears,

The rubber is exactly as you saw in the shellac thread. You can mix your own shellac easily by putting flakes into a container and just covering them with meth. Personally I don't like pre mixed shellac because it does have a shelf life whereas shellac flakes are easily kept indefinitely.

PVA glue is water based and so the medium used to thin it is water. When thinning PVA glue for veneering I usually work on ten per cent water added. You should end up with the PVA'd surfaces covered in a transparent film of PVA. A household iron set on high temperature reactivates the dried PVA glue just enough to allow it to grip the veneer and the ground together. A slow firm pressure is required and will not scorch the veneer. Yes in early attempts you might do so but usually the use of a scraper will remove any marks. Once the PVA is set it takes a great deal of heat to totally break down the bond. If you find you have a bubble where the veneer has not taken you can slit the veneer carefully and insert a little glue. If this happens I place block over the reglued area. I cover the block with packing tape which I use often in my workshop but even a piece of glad wrap or something similar oveer te veneer and under the block would do.

As with any process that is new to you I state the obvious. Get a small piece of scrap and practice.


Jerry

War does not decide who is right. War only decides who is left.

[astrid]

My veneering technique is a bit more traditional

Carefully prepare surface
apply PVA thinly and evenly with a grouting tool or similar and use a printers roller to squeeze out excess glue and any air bubbles.
cover with paper or gladwrap to stop the battons sticking to the veneer and place wooden battons across the surface at 12'intervals
place 2 or three battons crosswise across these and clamp them down to your base.
This applies equal pressure over the whole surface.
veneer should be firmly fixed with no bubbles.

Astrid

[AlexS]

Both Jerryc's & Astrids methods work. One further tip: spray a mist of water on the outside of the veneer before you apply the glue. Stops it curling when you're laying it down.
My preference is for the hot iron method, but that's just me.

[jerryc]

Beat me to it Alex. Remembered the important fact of wetting surface late last night and was going to fix omission this morning.

Jerry

War does not decide who is right. War only decides who is left.

[Cloth Ears]

Thank you all. When I eventually get to it, I will provide pictures of both successes and failures (hope there's more of the former).