What Is This Due To?

[Metal Head]

Hi,

I had to reduce the width of an interal door as it was sticking. However, I noticed some of the paint was loose, so I pulled it off. Unknowingly there was whole areas where I was able to peel it of like orange skin. This is the first time I have had to deal with this type of situation - btw we didn't paint the door previously. So it this the result of not having sanded the surface between coats previously thus not keyed and able to take a grip, or is it's cause due to something els?.

Thanking those in advance of their reply(s).

Regards
David

[Skew ChiDAMN!!]

Either poor prep work or the door was handled after sanding but before the primer... (which, I s'pose, is still poor prep work.)

Can you tell if the door was painted before or after 'twas hung? (Paint under the hinge is a good indicator.) It may've been prep'd, then hung, then painted... far from the ideal order, but often happens in rush-jobs. The area around the hinge can absorb oils from the skin of whoever hangs 'em, and hung doors are a pain to paint so often get shunted to the apprentice... who can rarely be bothered re-sanding what's "already been prepped" regardless of what they're told. (This is assuming that the door was even sanded at all.)

Or it could be something completely different!

[joe greiner]

Most paint failure is due to poor surface preparation. This can work to your advantage, of course, if you want to replace the existing coating, as it makes the old stuff easier to remove. Could be an inappropriate original coating, but poor prep work is still most likely.

Joe

[floobyduster]

Check if the bottom and top coats of paint are the same ie enamel or acrylic. If you slap a coat of acrylic over enamel that can happen - especially if the correct undercoat hasn't been used.

[Trav]

I'd say it is almost definately due to having an enamel undercoat and a acrylic top coat.

Start stripping it off, or buy a new door.

Trav

[gregt]

How can you tell the different paints apart? ie: Acrylic V's Enamal let alone what sort of undercoat was used?

[Wood Butcher]

Someone told me that to check you wet a rag with turps and rub it on the painted surface. If some of the colour comes off onto the rag then then paint is enamel, if no transfer then it is acrylic.

Not sure how reliable it is but worth a try.

[echnidna]

I agree with trav about an intermix of acrylic and enamel paints.
Strip it off or replace the door.
BTW turps won't dissolve enamels once they are dried.

[Jacksin]

Just to confuse the issue. I was told to try the rub with a turps-dampened rag and if its acrylic some of the colour will come off.

Quite the opposite to what Wood Butcher claims?

[Big Shed]

Lots of generic names being bandied about here! If it is a solvent-based enamel, then rubbing it with turps won't do anything. If it is a water-based acrylic (yes Viriginia there are solvent based acrylics, just as there are water-based enamels!) then rubbing it with metho will dissolve it slightly and make it sticky.

Looking at the picture, my guess is that this was previously painted with a solvent-based enamel and over-coated with a water-based acrylic without any surface preparation. This has resulted in a failure in inter-coat adhesion and you should be able to strip most of the top-coat off by hand or using a heat gun. Once this is done, sand the old surface properly, undercoat with a good quality water-based primer/sealer, then paint with your choice of topcoat. Without knowing whether this is an interior or exterior door it is hard to say what would be the appropriate topcoat.