Got a "shabby chic" garden sign which is made from mdf. I want to protect it from the elements with some sort of varnish but I think it has to be sealed first?
The sign will hang on a wall in the garden, therefore it will be exposed 24/7.
Advice welcomed!
Dilute the varnish first (white spirit if a traditional type, no idea for some of the modern ones) then soak the sign in it. Repeat several times. Have low expectations...
Immersion in diluted yatch varnish ought to do it. A properly applied coat on real wood has lasted nearly a decade for me away from the sea.
Not sure that high gloss yatch varnish counts as shabby chic but it is immensely durable if you obey the usage instructions to the letter.
A friend of mine (the one who had a slight mishap with a canoe and expanding foam) made a fine sign on MDF for his daughters chicken house. As those who are aware of the canoe mishap saga may appreciate he is a somewhat unwordly soul despite his intelligence. Having made the sign he was much put out to discover that signs for chicken houses went on the outside, not the inside for only the chickens to admire.
Varnish wasn't an option as it would have disrupted the rather fine artwork so he obtained a length of PVC drainpipe which the sign could fit into and assorted fittings and constructed a vacuum chamber. This was connected to an old fridge compressor as the vacuum pump. He put the sign in, filled it with a slow setting resin, set it all going and went for a cup of tea. To the amazement of those of us familiar with some of his Heath Robinson efforts after about an hour he had a respectably low pressure. He left it for about another hour then slowly released the vacuum and allowed the apparatus to come back to atmospheric pressure. The sign was allowed to rest in the resin for an hour then taken out , allowed to drain and left for several hours for the resin to set.
Several years later and it is still in place and in perfect condition. The apparatus would have been reusable had he not forgotten to pour out the surplus resin and clean the pipes where resin foaming as the air was extracted from the MDF had collected.
May have been better pulling a vaccuum without the resin in first, (to purge the air), then "somehow" introducing the resin into the chamber, then de-pressurising - so atmospheric pressure forced it in....
Still it worked obviously
Jim K
My vote on the sign would be a coating epoxy - thin runny stuff designed for this. Then varnish to protect the epoxy from UV.
But I wouldn't use MDF.
Andy
The sign, if an external one, may have been made from exterior grade mdf
1220x2440x18mm Exterior Grade MDFDescription
Medite Exterior is an MDF panel developed specifically for use in a wide ra nge of external applications in accordance with MDF-H2 as defined in EN 622 part 5 and gives all the design freedom of Standard MDF. Used as a substit ute for softwood, hardwood, plywood, plastic and metal in non-stressed appl ications. It can be used for a wide range of external applications includin g: External signs, shop fronts and external woodwork including fascias, ext erior mouldings, door parts - raised and fielded panels, garden furniture c omponents, exterior display stands, marine craft interiors and sports score boards.
Never tried it myself though I have seen various pieces in Garden centres d esigned for external use using it.
What I have seen has had a slight green tinge to it in its narural stste.
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