WendyG Posted April 9, 2012 Share Posted April 9, 2012 I carefully undercoated and painted our metal shutters (using French UV resistant metal paint) last summer/autumn.Now the paint is peeling off in large "curly" strips right down to the bare metal. Sometimes an expansion/contraction type sound appears to come from the shutters. I am wondering whether this winter's extreme cold has had something to do with it.Before I go through the whole process again I would be most grateful for any advice.WendyG Link to comment Share on other sites More sharing options...
Théière Posted April 9, 2012 Share Posted April 9, 2012 Are the shutters galvanised ( zinc plated) under the paint? Link to comment Share on other sites More sharing options...
WendyG Posted April 10, 2012 Author Share Posted April 10, 2012 Hi Thank you for your prompt reply. No, they are not galvanised, it appears that whatever paint was first used on the bare metal has caused a reaction and made the new paint and original to come off right back to the bare metal.The original owner, now deceased, used to use anything that was free or cheap on the property,WendyG Link to comment Share on other sites More sharing options...
WendyG Posted April 21, 2012 Author Share Posted April 21, 2012 [quote user="WendyG"]Hi Thank you for your prompt reply. No, they are not galvanised, it appears that whatever paint was first used on the bare metal has caused a reaction and made the new paint and original to come off right back to the bare metal.The original owner, now deceased, used to use anything that was free or cheap on the property,WendyG[/quote] Link to comment Share on other sites More sharing options...
Quillan Posted April 21, 2012 Share Posted April 21, 2012 The reason the paint comes of is because it is not stuck (or keyed) to the metal properly in the first place. The main reason for this can be that the surface is not clean and the wrong primer used. Some people get confused with the terms primer and undercoat, they are not the same. Good metal primers are usually 'etching primers', these have a mild acid or something similar that eats slightly in to the metal to make it stick. The primer acts as a 'key' for the undercoat which in turn makes a key for the top coat. The surfaces should be 'degreased' before the primer is applied. You should use gloves as your skin gives off grease so you should not touch the clean metal with bare hands once cleaned.This is how I would do it. Use a scraper to take of all loose paint, if it comes off with a scraper then it's not stuck properly. I would then take a wire brush to the surface (one you put in an electric drill) to get off the rest of the paint that has not stuck and to make a rough surface for the prier to stick to. I would then apply a primer, wait the prescribed time then undercoat, wait the prescribed time and then the top coat. You don't want long gaps between coats as this give the opportunity for more grease etc to get on each new coat. Better than using a scraper and wire brush and a way that definitely fixes the problem is to remove the shutters and get them sand blasted.If you follow this advice you won't have to do the whole thing again next time, just sand lightly and repaint. If you Google 'painting metal' there are loads of tips and basically they are as I have mentioned. Make sure you use oil based paint as this will inhibit rust. Link to comment Share on other sites More sharing options...
Chancer Posted April 21, 2012 Share Posted April 21, 2012 Are you sure that they were not galvanised?The bare metal where the paint has fallen off, is it rusty?If not then you have either a hot dip galvanised or electro_plated (which is not the same thing despite many claims) finish, which needs special preparation, in fact the only real way to get paint to adhere to galvanising is to let it weather for several years before preparation. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.