interior and hatch veneer question

[Guest mark]

Has anyone ever applied veneer after the fact? I mean to faces like the hatch cover or inside the cabin walls...I've used marine plywood, but was contemplating adding some nice mahoghany veneer to some rather large surfaces. Would this be a problem under epoxy, or would it act like "just another lamination?"

[Tim Diebert]

This would be pretty much impossible Mark.

Your problem is not the coating over the applied veneer...the problem will be properly applying veneer to the surface required (now I'm sounding like Beaker....)

Don't even think about that iron-on stuff or using contact cement. Veneer has to be glued to wood just as though it was a larger, more solid piece of wood...with wood glue. You need pressure, cauls, clamps and plattens etc.

Veneer can applied to a curved surface with a technique called 'hammer-veneering'...chances are you are not going to want to go to the trouble. If you are...contact me off-forum.

...vacuum bagging is another method....

[Barry Pyeatt]

Mark, listen to what he says, Tim has had to do this as a professional for a long time. Veneers are touchy. They are wonderful, they are difficult to make work in this type of application. They generally end up delaminating and looking like you would rather have painted. If you want to see how it would work, find a piece of iron on edge tape and apply it to a small piece of finished work that has been coated with epoxy as you are stating. Then after applying it as instructed run it thru the dishwasher a couple times. If it is still attached and looking the way you want it to, then you will be quite lucky. Doesn't take much moisture exposure to destroy veneer work. Just humidity/temp changes can cause all manor of distortions and delamination.

I would stay away from it unless you have the equipment and experience with it already.

Now then...having said that, I have seen some inlay work of thicker materials that have been well done and have held up pretty well, but there again, once they are exposed to the elements, they tend to have problems with them as different wood types expand and contract differently with temp and moisture changes. Not the thing you want to have to deal with on a boat.

[High C]

I'll third that. Veneer is for pros and very skilled ams who have the right tools. Have you ever held a piece of veneer in your hand? It's so thin, I can't imagine how it was cut in the first place, or how I could even get home with it in one piece.

I'm about to start making my hatch tops. There are two, the foredeck, and another at the front of the cabin roof. I'm going to make them out of solid cherry, strips maybe 1.5 inches wide, and bright, of course. I'm hoping they'll be the main focal point of the boat. I'll post pics when they're ready.

[Guest markfitzgerald]

I've been suitably convinced. I restore old 30's and 40's wooden radios, and have used veneer quite a bit, but you're right -- the radios don't (in a perfect world) see much in the way of water.

Now that I've got that ugly white seam sealer all over everything, what can I use to put a nice fillet over it and make everything smooth before painting?

[Simon]

Not to dispute with the experts, as I've no experience with it myself, but can't you use staples to attach the veneer (as in cold moulding)? :roll:

[Barry Pyeatt]

Placing and securing the veneer isn't the challenge per se'. The challenge with placing thin veneers on boats is the marine climate and the fact that most boats are ether left in the water year-round (marina) or on a trailer (out of doors). Temperature variations and humidity variations all work to defeat the detail work. Different woods and different wood grains expand/contract at different rates causing no end of problems with veneer. Hence the need for floating panels in paneled doors on furniture or the door breaks with panel expansion or contracts and causes other problems with fit if they don't move. Same with plywood with solid wood edging on it. Veneers just pop loose over time. Veneers placed on flat plywood surfaces expand or contract and the joints just give way and moisture enters the joint and destroys the work.

If you want to see how this works just place a square veneer patch on a piece of plywood and put 4 mitered strips along the edge of it to frame it. Epoxy them in place, or use contact adhesieve or anything you want to use. Then finish it off with the best marine varnish you can find. Let it set outside for a few months over a change of seasons and see how it holds up. Staples won't make a difference, the wood veneer will split along the staples.

Cold forming is a different situation and you are generally laminating plywood strips, they are stable because of the cross grains.

We have to face it....wood moves with the changes in moisture and temperatures. Higher humidity changes and temp changes result in a lot more wood movement. A long board gets longer and then gets shorter again. Just with the change of weather. Unfortunately you can't seal it out, you can only seal it in.

Hope this helps.

[Simon]

For the sake of conversation (I've no intention of messing-about with veneer very soon), if you epoxy-glued the veneer on cross ways to the grain of the plywood, stapled it, and then removed the staples afterwards, what would be the major difference between this and another layer of plywood? I'm assuming here that you manage to get good contact and the joint is good. Surely there is no more reason for this joint to fail than one of the laminations of the plywood, which would be glued on themselves with an (presumably) inferior glue to epoxy.

Is cold moulding always done with plywood? I thought I'd seen it done with veneer, could be wrong though. In essence by cross hatching the layers you would be building a custom sheet of plywood in the shape of a boat. This wood swelling issue is going to get me in the end .... :?

[Frank Hagan]

My failures with veneer have been due to having wood beneath them ... and having the base wood move at a different rate than the veneer. I don't have any experience with veneers over plywood, though, and I see Simon's point.

But I suspect its much too much trouble and expense to attempt, and have fail. Now a nice formica sheet might look nice ... :roll:

[Barry Pyeatt]

Good points Simon,

Making up plywood involves a great deal of pressure in addition to the glue.

The woods used are of course set at angles to one another and have pretty much the same expansion/contraction characteristics.

When we apply veneer, unless we can duplicate that pressure and adhesion we have a compromise. Not at all bad for something that is going to be relatively well protected.

My point is that we are attempting to do something that is not as well protected. And it is usually subject to all the various temp/humidity/moisture changes that occur. Not that we can't do it. Certainly there have been a lot of people do inlay work, veneer work and mix various woods and have gotten away with it.

A real good example of what can go wrong is trying to edge glue two dissimilar woods such as say Oak or Ash and try to glue them to lets say even a stable base such as plywood. Maybe it is just a rubrail being glued to the plywood. The likely hood that there will not be a separation problem is very low. The two woods simply have too much movement with the seasons to allow the joint to work. So... It can be attached, but it needs to be bedded in something that will allow it to move with the changes. Woods that don't have so much movement along their length would be better choices. Cedar, Mahogany, Pine, Fir, Spruce.

When we take a veneer, very thin material and put it on plywood, it is wanting to move with the base, that would be relatively little in the case of a hardwood such as birch ply, but something like pine or doug fir ply that will check with just temp and humidity changes will cause the veneer to wrinkle within a relatively short period of time. We can't do anything to stop it. Hardwood veneers grow and shrink along their grain differently than softwoods and differently than each other.

I've done some nice inlay work with veneers in the past, some of them pretty involved with a lot of different woods and using vacuum press to adhere them Even after finishing and keeping them indoors there has been some separation with the seasons. If it is planed for, then it can move and the small separations are not to visible.

But I did a nice round table for our patio in Michigan with 1/4" veneers over plywood and epoxied it all down. Would have probably been Ok but for the fact that the different hardwoods expanded and contracted differently with the seasons and it all broke up ultimately. Finished panel developed hairline cracks at the end of the season and by the beginning of spring it had a lot of moisture drawn into it. End result, buckling woods.

This was on a covered and enclosed, but not heated patio.

So...yes, we can do cold molding with veneers to make up our own plywood. We need to pay attention to the wood used to be consistent with it if we want it to be stable. We can staple the strips in place while the epoxy sets up. And we can finish it. It should be quite stable, but after you have done this, I wouldn't try to apply a different veneer to the surface. It will generally have problems. Just the wonderful world of wood.

I even worry about making up dissimilar stripped sections with edge glued woods, different woods, different characteristics. Then try to wrap a wood frame around it and apply a finish. End result is beautiful, for a while. Next year it will probably have cracked. Wish it wern't so.

[Barry Pyeatt]

Mark,

We got a bit off the question you asked. If you want to apply mahogany to your hatch cover, then I would apply a thicker piece of wood to the ply. Maybe 1/4" strips. Even better would be to use thin Mahogany plywood and epoxy it to the underlayment. (This combination of ply on ply is quite stable.) The problem is when you use boards or veneers on other boards or join with other woods. Epoxy them down and apply even weight to them to hold them inplace while it sets up. You will probably want to wrap the hatch at that point with a frame. This is where you will likely have a problem in the future. The wrap that goes with the grain of the top will be fine, the wrap that goes across the grain may be where you have a problem. If you try to miter the corners, they will probaly split on you eventually. If you but join them they will seperate a little and you will have a crack along the edge. If you do half laps they will probably have a little better stability and the wood movement (if mahogany), will probably not be too much for the joint to handle. I would avoid using dissimilar woods to wrap it. If you use Mahogany, then stick with it. If you use Cedar or something else, use it all the way. Try to not mix them where the joint will be highly visible.

[Brent]

When strip building canoes I have had some success making decorative designs by using different color strips forming something of a wood strip fresco. This is different from veneering in that there is no underlying support wood to move at a different rate than the surface wood. Additionally, while the woods used may be different species, all have the grain oriented in the same direction so that they tend to move together instead of in opposition. I am confident this approach could be used to make a very nice hatch.

Some builders will build the entire deck out of one wood (maybe western red cedar) then build a large panel out of another wood (mahogony or cherry). A curved design is cut in the second panel, then this design is scribed into the original deck and a cut out made to the same shape as the curved design (keep the grains running parrallel) All is epoxied in place.