Problem painting a garage door

[TomH91]

I decided to give my metal garage door a long overdue coat of paint on Saturday. It was my first time painting a garage door so I tried to get clued up as much as possible (but evidently not enough).

The original paint was just extremely faded, there was no peeling or bare metal, so it was my understanding that I wouldn't need to use a primer or undercoat. I just gave it a good wash down the evening before.

I used Hammerite Garage Door Paint (burgundy). I noticed as I was painting that some of it was starting to sag. I tried to rectify this quickly but it had already started to dry and become slightly goopy, so it eventually dried like that.

After going outside to look at it today (3 days later), the parts where it has sagged have started to wrinkle and blister. I'm not sure why this has happened. I used a thin coat in my opinion, although I did paint it when the sun was shining on it. Could that have had an effect?

I still need to add a second coat. So my question is, is there any way I can get rid of the wrinkles and remove the sag marks without starting again? Would a second coat rectify any of this?

Any help appreciated. This is becoming a minor disaster

 

[TheDec]

It may be that the Hammerite reacted with paint on the door, difficult to say really, you will need to scrape back and sand the areas before repainting them. And you be better using an alkyd gloss as opposed to Hammerite.

Dec

 

[dcdec]

hammerite doesn't have good flow so its nor the best option anyway, i hate the stuff, as dec says gloss is better.
You've put the paint on too thick thats why its blistered, also an appropriate coloured undercoat will give a sounder surface and a good base for the best results in your top coat. Again as dec says you may be able to scrape it off as the paint wont be dry yet, you could also try a heat gun working carefully to just remove the hammerite. Just as a precaution i'm presuming you can burn off hammerite safely but maybe worth checking the health and safety blurb.

Use a 3inch brush or a mohair mini roller for speed which should help avoid working into paint thats already starting to dry and plan your work to avoid direct sunlight

 

[TomH91]

HI guys, thanks for your replies.

I just had a sand down of a few wrinkled spots. It's smooth but has kind of left a tiger print mark. Will this be shown through the second coat?

Which is better for application, roller or brush?

 

[TheDec]

I would use the roller to apply and lay off with a brush.

Dec

 

[TheDec]

Sorry that mark needs to be removed as it will show through the paint.

Dec

 

[joe-90]

The Hammerite binder is similar to cellulose thinner and will remove ordinary paint.

 

[sparkwright]

The original paint was just extremely faded, there was no peeling or bare metal, so it was my understanding that I wouldn't need to use a primer or undercoat. I just gave it a good wash down the evening before.

Did you give the original paintwork a sanding all over before painting? If not I would expect the new paint to start peeling.

 

[TomH91]

The original paint was just extremely faded, there was no peeling or bare metal, so it was my understanding that I wouldn't need to use a primer or undercoat. I just gave it a good wash down the evening before.

Did you give the original paintwork a sanding all over before painting? If not I would expect the new paint to start peeling.

Uh-oh. No I didn't. I read elsewhere that you only need to sand if paint is peeling. Looks like this job is going to get worse before it gets better

Thanks for the responses so far. The weather seems to have taken a turn for the worse so I won't be able to do any more to it for a few days.

 

[Growler]

The Hammerite binder is similar to cellulose thinner and will remove ordinary paint.

Nice to see a bit of experience every now and then.

 

[sparkwright]

Unfortunately, peeling is usually caused by not sanding. Sanding provides a key for the paint to adhere to.

The problem is you can have an old painted surface which is faded but otherwise in good condition ie not peeling. People think that it's in good nick and doesn't need sanding. But by putting on a new coat of paint without sanding the new paint can often peel off, sometimes quite quickly. Being outside the paint is more prone to peel. This is more common with oil-based paints on wood or metal. This isn't such a problem with water based paints on walls etc.

 

[TomH91]

Oh God, I wish I hadn't bothered now So is it pretty much certain to start peeling then?

 

[jondecs]

The Hammerite binder is similar to cellulose thinner and will remove ordinary paint.

Nice to see a bit of experience every now and then.

Yeah But!!!! Hammerite garage door paint is is an enamel thinned/cleaned up with white spirit.

Myself when I do a 'sound' metal garage door same colour, I abrade lightly to dull, wash, and one/ two coats of conventional gloss only.

 

[TomH91]

I'm such an idiot. Every website I've looked on now mentions sanding to allow the paint to adhere properly. I have no idea how I missed it.

Do I get rid of the paint and start again, or do I pray and hope for the best that it doesn't peel?

 

[jondecs]

Difficult to estimate when/if it will peel, did you clean/dust off even ? Peeling can happen as soon as paint cures after about 30 days. Or. Sometimes lasts untill the next time it's being painted and a lot of bad language when paint comes off in sheets.