Plywood

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  • #643017
    Mark68
    Participant

    What do you think of plywood? I tend to stay away from it most of the time because I see it as inferior to natural wood (probably because I don’t know what I’m talking about).

    What are its pros and cons?

    "Sawdust? I think you'll find that's man-glitter."

    #643042
    Ed
    Participant

    I currently use it for cabinet backs and, in some cases, cabinet panels, e.g., on a tool cabinet. In the past, I’ve used it for the cabinet itself, but then the joinery was with pocket screws. Ply comes in many grades depending upon the quality of the surface veneer, whether there is high quality veneer on both sides, and the presence of voids. One thing to be aware of with ply is with regard to finishing. Especially if the surface veneer is particularly thin, there is a barrier of glue very close to the surface and this can affect how the surface takes color and finish. Since the surface veneer is thin, there is very limited opportunity for sanding and even less for planing to level up surfaces or to remove defects. Around here, a 4×8 sheet of 3/4″ oak ply is $55 in the home center. Let’s call it 60 to $65 if you found higher quality. Even so, 32 sq. ft at $65 works out to around $2 per board foot, which is cheap for an oak surface, especially if you can find quality ply that hasn’t been mishandled.

    Those are the pros and cons that come to mind. Of course, the mixed orientation of the plys means that, no matter how you run your tool, you are going to worry about, and likely experience, break out at the edges with hand tools other than saws.

    If I had a number of cabinets to make, say for a kitchen or bath, I’d definitely consider making the carcases from ply and then adding solid wood face frames and doors. The bulk carcase work wouldn’t be hand tools, though. I’d reduce the ply with a circular hand saw and track / fence.

    #643061
    Mark68
    Participant

    Thanks for the in-depth reply Ed.

    What’s it like for resisting water?

    "Sawdust? I think you'll find that's man-glitter."

    #643077
    Benoît Van Noten
    Participant

    It is nice for box bottom and drawer bottom, in a groove (see workbench drawer in the workbench-customisation series )

    If you can find it, marine quality plywood exist. It doesn’t mean it must not be varnished.

    There is also a kind of plywood used to pour concrete in it. The faces are treated with a dark brown resin and are slick (when new) but on the long run humidity will penetrate by the edge if not treated.
    P.S. has used it as vise jaw liner on the 2012 workbench, if I remember well.

    #643111
    Larry Geib
    Participant

    There are two types of phenolic paper coated plywoods. That are used for different purposes.

    The type Usually used for concrete for work is technically called high density overlay (HDO). The coating is designed to not stick to wet concrete and is fairly waterproof. It also means the slickness And smoothness Of the the surface is such that it doesn’t take paint or finishes well and it of limited utility for other purposes. It has more resin than MDO. The smooth surface of HDO gives a very smooth concrete surface, mimicking steel form work. It should be coated with a release agent when used for form work. Canola oil based products like modern chain saw bar oil work well and are environmentally sound.

    Probably of more use for most work is Medium Density Overlay ply(MDO). It is designed for outdoor use, particularly as the material used for highway signs and comes with a matte finish that takes paint better. The overlay is available on one or both sides. PVA glue and epoxies will also stick to it. Years ago I built a clamming skiff with an MDO bottom and it held up well until I sold it 15 years later. I also built some planter boxes when I moved into my current house in 1993 and the planters, lined inside with a urethane roofing product, are still doing well. ( the cedar trim needs repainting, though.) I did also coat the horizontal top edge with the urethane, but the sides and bottom only have primer and paint.
    While MDO can be used for form work, that isn’t its real purpose. it comes in several grades.
    With both products, edges should be sealed with a primer, preferably oil based, or with a marine epoxy in particularly harsh environments.. that’s true for any ply.
    And the phenolic resin makes both surfaces more durable than ordinary ply.

    #643114
    Ed
    Participant

    Mark, Regarding resisting water- Sorry, but I don’t have any experience in that regard. (Edit: Larry and I must have been typing at the same time…don’t see a way to delete my post at this point.)

    • This reply was modified 2 years, 7 months ago by Ed.
    #643423
    GfB
    Participant

    I’ve used box store beech veneered ply. The veneer is very thin, and I had to be very careful about sanding (like Ed said). I couldn’t find any actual good quality rolled veneer in my local stores.

    Glue – All the glue in ply is somewhat harder on your tools that solid wood.

    Sawing – Always produces bad tearout, unless I ensure to knifewall both sides of the ply, on both sides of the blade. For clarification, that’s 4 walls per cut. Not terrible, but certainly a big oops when you realize what you didn’t do.

    Dovetails – I enjoy doing them. The multi-layered nature of ply makes it a cinch to pare and chop.

    Dados – I hate doing dados in ply with a router plane. Unless I go very slow, knifewalling each layer, it’s inevitable I’ll get tearout of the layers, even with a newly sharpened blade.

    Overall, plywood is doable, can be a cheap alternative, and can produce nice looking results. But the layering creates a weak condition that we have to be careful in how we approach.

    #643450
    Sven-Olof Jansson
    Participant

    Many thanks Ed and Larry for expanding and deepening my understanding of plywood!

    Meranti plywood can perhaps, at times, be an alternative to the more expensive Baltic Birch variant. It has been very well suited for renovating the walls at our croft. The original walls are shown on one of the attached photos. (Back in the -50s the municipality paid for fibre boards as cover – funding wasn’t sufficient for truing more than one wall). I was given the tip to moisten the surfaces with a damp cloth and then sand the risen fibres, before painting the meranti. Crofts usually don’t have mahogny-like panelled walls.

    As Ed points out: making multiples of a cabinet is time consuming, and if one is to live at the place while they’re being put together, then getting to the finished state quickly becomes quite important, I believe. I used morticed-tenoned frames and plywood panels for the wall hung kitchen cupboards: a bit rustic perhaps, but time was quite premium; and it is after all a croft.

    Plywood has also been of value for prototyping. The one shown on the attached photo clearly tells that for that particular spot, other dimensions are needed for a floor standing cupboard (done in a couple of hours, though).

    Sven-Olof Jansson
    London, UK; Boston, MA

    #643460
    Mark68
    Participant

    Very informative; a lot more going on with ply than I first thought.

    Thanks all for the feedback, much appreciated.

    "Sawdust? I think you'll find that's man-glitter."

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