Varnish is just paint without the colour..its still too brittle, metal expands and contracts with heat..more sure if its painted black, which as Eddie said wiill soak up the heat.
Wash it down well, with sugar soap or soda crystals, (you'll have some under the sink ) whilst washing it down, use wet and dry sandpaper, 400 grade and in the grooves, scour along them with one of those green things, (you'll have one on top of the sink )
This would've been a perfect job for Crown Solo One Coat Self Undercoating Gloss , but...you want matt. (Even Zampa could've used this).
The only 2 things I can think of are Black undercoat, but it wont have the lasting qualities of Gloss.... or 2 coats of Dulux or Johnstone' or Sandtex smooth black masonry paint. Easy to apply and long lasting.
You must rub it down well, to give it a good key.
Your problem will be the heat. If you get the sun on it at all, it will get red hot, but at least there will be no knots in it.
It's not that the door will get hot, it will radiate into the garage, which you might not want. My garage door is painted dark blue, and when the sun's on that you can feel the radiant heat on the inside a good few feet way.
Good theory with the undercoat and I reckon the best bet...I was actually going to suggest it but I thought I'd give growler the opportunity to be right for a change...
Thanks for all your help lads, undercoat it is then, the door is in the sun all day, so I suppose it will turn the interior of the garage into a blast furnace! Out of interest, I wonder how much cooler the door would be if it was painted white?
Thanks for all your help lads, undercoat it is then, the door is in the sun all day, so I suppose it will turn the interior of the garage into a blast furnace! Out of interest, I wonder how much cooler the door would be if it was painted white?
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