Finishing a veneered MDF mantlepiece

alexlyne

I have just had a mantlepiece (aka shelf) made to put in an alcove.
It is sapele veneered 18mm MDF.

To make the shelf look thicker, I have 12x45mm strips of real sapele to stick to the edge of the MDF. I am yet to cut these to the appropriate sizes (they will be mitred as the edge of thelf is not uniform).

I now have two things to do: fix the edging to the MDF, and also treat/finish the wood surfaces.

1. fixing the edging. One idea is to fix batons behind the edging and screw into the edging and the underside of the shelf. Should be pretty tough, and I can use woodglue to ensure the edging stays put.

2. Treatment. I am thinking of using a polyurethane based varnish to give a good hard finish. However I am open to suggestion. If I use standard (decent quality) varnish should I put down a thinned primer on first, should I use a clear varnish or a coloured one? Should I treat the edges of the MDF as well?

Your suggestions and advice is appreciated :beer:

DirectDebacle

1. You could use battens. Screw through the batten into the rear of the edging ensuring the screws don't come through the face of the edging. I would just use a good PVA. I really like Titebond but any good quality PVA will do the job. Make sure you have enogh clamps to hold the edging in place while the glue sets.

2. Polyurethane is fine. Do not treat the MDF edges if you are going to glue the edging. You want to be gluing to the sapele veneer not to varnish.

Apply 3 coats of varnish sanding lightly between coats.

coat 1. 60 (white spirit)/40 varnish. This thin coat soaks into the wood and dries rapidly.

coat 2. 40 white spirit/60 varnish. Ditto^ ^

coat 3. a light coat straight from the tin.

If you want to change the colour then apply a woodstain before the varnish. Use clear varnish.

Note clear varnish will slightly darken the sapele in any event.

alexlyne

Thank You

Just to clarify, the edge of the MDF is not veneered. I was worried that the mdf would then soak up any glue too quickly. (so I would possibly use watered down pva first, like wot i did on the plasterboard in the bathroom before tiling).

DirectDebacle

No. Apply the PVA direct to the edge of the MDF and to the edging strip. Clamp up and excess glue will be squeezed out. Wipe this up immediately with a damp (not wet) cloth. Most PVA will give you a working time of about 10 mins, so you will have time to adjust alignment of the mitres if necessary, before the glue starts its initial set.

alexlyne

OK, super. Thanks DD