Paint not adhering to surface.

[peweuk]

It has been a while (about 10 years) since I had to do any exterior metal paintwork - and I am looking for some advice.

We have a Garador Garage door which still has on it the original black paint applied at the factory and is about 3 years old.

We decided we wanted to change the colour to match our front door which we are going to re-paint (not yet done).

To get the colour we wanted we bought a Valspar Exterior Metal and Wood Gloss Paint in the mixed colour from B&Q just before the current lock-down.

On the tin is simply says that the existing paintwork should be sanded down before application - which we did. No mention of primer or undercoat except for new untrated metalwork.

However, once applied (to a test area which had been sanded) and dry I find that I can scratch the new paint off completely and easily with my fingernail - the new paint seems to have covered but not adhered to the old paint.

My question is - is this a possible problem with the original paint used by Garador, or is it a problem with the Valspar paint (which I assume is water based as it says brushes should be cleaned in warm water), or is it likely to be a compatibility problem between the two.

Any thoughts would be appreciated.

 

[footprints]

Some doors have a plastic finish. I remember when I had my first up and over fitted the fitter said they did not take paint well, a special primer like Zinsser Bullseye 123 might work on them, but in your case it is too late. Keep your fingers crossed though most paints dry in 24 hours but may take several weeks to cure depending on the weather conditions, treat it carefully for couple of weeks and you may get lucky.

 

[peweuk]

Some doors have a plastic finish. I remember when I had my first up and over fitted the fitter said they did not take paint well, a special primer like Zinsser Bullseye 123 might work on them, but in your case it is too late. Keep your fingers crossed though most paints dry in 24 hours but may take several weeks to cure depending on the weather conditions, treat it carefully for couple of weeks and you may get lucky.

Thanks for your feedback.

As it happens I had only tried a test area on the door.
After my original post I sanded off the new paint and instead of a 'light sanding' as recommended by Valspar I sanded the original paint quite heavily until the original black paint looked more grey.
I washed of the sanding dust and tried again. This time the paint seemed to adhere - but tomorrow, after a few hours curing, will tell.

So it looks like you could be right about there being something about the garage door paint.

 

[peweuk]

Message deleted - It's OK - found my answer

 

[peweuk]

I purchased some Zinsser rather than face sanding all the profile detail on the garage door - and it failed.
I cleaned the garage door as directed and applied a coat of Zinsser - however after drying I find that this too peels off if you scratch it with a finger nail.

So having wasted the money on Zinsser I now still have to sand the whole door - which is not going to be fun and will take ages

 

[footprints]

Zinsser takes a couple of weeks to cure fully it will scratch off before then

 

[footprints]

https://www.renovateforum.com/f207/zinsser-bullseye-123-curing-time-76050/

 

[peweuk]

Thanks guys.

As usual, knowledge is king - and there are a few members of royalty here

I wrote to Zinsser. Not expecting a quick reply under the current situation I received this quite quickly endorsing your replies

"Thanks for the enquiry.
Unfortunately we do not know anything about the manufactures of the door you are painting our best advice would be to contact the manufacturer (Garador) to find out what Products is bets when recoating, our Bullseye 123 is an excellent primer sealer & should adhere to most surfaces, how long was the door left before you tried a scratch test as the product takes 7 days to reach full cure not worth trying to do a test on adhesion until after that time.
I trust this information is helpful, if I can be of any further assistance please do not hesitate to contact me."

I will leave my test area until next week and hopefully confirm that there is not a problem between Zinsser and the garage door coating. I have already carried on with the other areas I needed to paint, and so far so good.

Thanks again guys.