Setting plywood repair plugs in such a way, that the concrete surface
will later show no indentation requires a little understanding of physical
properties of wood and water.
Processed wood directly from the factory has a moisture
of ca. 8 per cent. Plywood panels, that have been used on site have a much
higher moisture content of ca. 30-50 per cent.
After setting the repair plug into the panel, it will
suck up moisture from the surrounding wood and swell. To avoid plugs from
sticking up from the panel’s surface, one must set them a fraction of a millimetre deeper so it has room to swell. We recommend half the thickness of a
fingernail.
Adjust depth stop of router to desired depth (we use a plug to see how deep we need to set the depth:
drill until depth stops
You can see the hole is declining towards the middle in the shape of a funnel. this gives room for excess glue to expand.
Apply glue to the edge
Set in plywood plug with a rubber hammer. As you can see in the picture below, it is a little "too deep". But as explained above, this is what we want. The plug will now suck up moisture from the panel and swell. it will be flush with the rest of the panel within a few hours or latest for the next pour.
You can download this guide as a pdf file from our website here: