Recently we
had a new client who asked us to paint some MDF shop fittings. Not a difficult
task to complete nor should it be too complicated for our multi talented team
of polishers and painters. Problem was he had
constructed a number of large bulkheads by butt gluing large sections of MDF
together and then puttying up the joins.
As is our
normal process, Craig spoke to the client and explained that no matter how well
he had glued the two sections together, at some time in the future those two
sections will move. This movement will then create a crack in the MDF join and
paintwork.
The reason
we take the time to discuss these issues is that we want our clients to be able
to install our paintwork with no fuss, and no dramas in the future. Spending a
little time on education at the start of the process is better than having to
fix a problem in the future.
Craig
offered a solution of applying a single sheet of laminate over the face of the
bulkhead, covering over the join and creating a single, unjoined surface, to
paint on to.
The client
was insistent that all would be fine because he had used biscuit joiners and top-quality
glue. Craig was insistent that some time in the future the join will move and
create a crack.
This is a
common issue that we deal with weekly. Often a client will say “they can weld
two pieces of steel together and it won’t crack. Surely gluing two pieces of
MDF is the same.” Trust us, it’s not the same.
Timber, MDF
and Chip board are all variations of natural timber products. They contain
anywhere from 10-15% moisture. As a result of that moisture content these
products can and will expand and shrink. Moisture can move in and out of the
substrate and can also move from one side of the substrate to the other.
Moisture moving in and out will cause the MDF to expand or shrink and moisture
moving from one side to the other will cause the MDF to bow.
This
movement will often cause a butt join to crack and when it does crack our paint
will crack as well. Despite many cabinet makers and shop fitters best hopes,
our two pack paint is not strong enough to hold two pieces of MDF together when
the glue cracks.
So, what’s
the answer?
Simply cover
over any MDF join with laminate to create a single unbroken surface. If the item
of joinery has one single piece of laminate glued to the surface, then whatever
happens to the MDF under the laminate won’t show through to the paint finish.
