Ok I think i messed this up - paint flaking alert!
Background: I'm doing up alot of things in our house atm - Kitchen (repaint w/Farrow & Ball), Bathroom & Ensuite change, etc.
All is going well with the above and between my mammoth of tasks i decided to fit in repainting the garage door. It's in good condition as paint was not falling off and no rust, etc. The colour was just faded and looking a bit naff.
What i did: I bought some Dulux Weathershield for exterior metal & wood. (In Gallant Grey for those interested). I brushed the door down to get rid of obvious dust and debris. I then washed the door with a soapy solution and cloth by hand. Then rinsed with fresh water and left to dry. I applied one coat of the paint by brush (decent quality one) and left to dry.
Results: Having looked at it this morning 90% of the door looks fine but 10% of it has bits flaking off. Now I didn't sand as the previous paint was matte to touch so I assumed it had a key for the new paint to adhere to. I didn't prime as the instructions said to only do so for bare galvanized metal or wood.
My only thought was maybe it was too cold to paint properly (read the can said over 10 degrees but it was probably around 4/5 degrees). But why would only parts then flake off?
So what do i do - help and advice needed! Do i just need to sand these areas now to prevent getting worse and repaint when warmer? Was it just the temperature that was the issue or should i have primed (red oxide?)
We're looking to sell the house so want it to look at least decent for now and really for the new people not to have to repeat in 6 months.
It's not recommended to paint in low temperatures and high humidity because it stops the formation of the dry film. Where the particals bond during the drying process they will not bond correctly and the adhesion part of the paint will not adhere to the substrate. This is especially true for metal areas as these tend to be colder. It's not just the air temperature it's the substrate temperature as well. It's very likely now that film is not as durable as it should be. One option is to sand it back and repaint, possible give the original areas a key to be on the safe side. But what may happen is that paint will gradually start to loose adhesion and take the new paint off with it.
Ideally you would remove it all and start again :-/
We would tell our customers not to paint late in the afternoon at this time of year as the moisture increases over night as the temperature drops and this effects the curing process. Start early and give the paint enough time to dry before the evening sets in.
You should not need to use a metal primer as you was not back to bare metal.
If you cannot wait for warmer weather could you get some heat into the metal door - possibly a fan heater blowing on the back. Also try heating the paint by placing can in hot water. Let us know how you get on.
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