Paint bubbling

[Vintage Veloce]

The front door sill on our 100 year old building is on a shaded porch. It has been well sanded, primed and painted multiple times over the last 5 years.
Last time it was painted was by professional in April... it immediately bubbled up days later. They came back and well sanded, primed and painted it again. It lasted for a while (3 months), but a couple weeks ago the bubbles started again.
This is in dry San Diego... and in this spot on the porch it has never been wet and never gets direct sun.
What could we be doing wrong? How do I treat this so it stops bubbling up?

 

[The Cobbler]

looks like moisture from somewhere getting to it

 

[Vintage Veloce]

looks like moisture from somewhere getting to it

Thats what I'd first think... but it really isn't imaginable. Besides being VERY protected by the covered porch, it hasn't rained here in months (since well before the painting three months ago), There is also no plumbing on that side of the house. That sill is probably 3 feet above ground level on top of a concrete foundation. It's bone dry.

 

[gahrajmahal]

At this point I’d call in the paint representative for whatever brand of paint your painter used. They might have the answer.

 

[The Cobbler]

strange

 

[egdede]

I'd suspect an oil soaked into the wood.

 

[Vintage Veloce]

At this point I’d call in the paint representative for whatever brand of paint your painter used. They might have the answer.

This is a good idea, I can easily stop by the Dunn Edwards store and show them the pictures!

 

[Vintage Veloce]

I'd suspect an oil soaked into the wood.

I wonder... it is a 100 year old house. Maybe the original sill was some kind of oil finish...? Much of the other woodwork and the door was possibly shellaced or something back then...

 

[The Cobbler]

it looks like there's another bubble between the first 2 you circled on the left of the picture. the bubbles are of forming an easy arc .
will be interesting to see what you figure out. good luck with it !

 

[Wolley]

Use paint stripper to get back to bare wood and start over.

 

[BillK]

The one on the far left looks like a perfect round circle. Is there a screw or nail at that point ? I agree with the others that you need to completely strip it and see what is there.

 

[Stuart in MN]

It has been well sanded, primed and painted multiple times over the last 5 years.

Besides the bubbling, this stood out to me...a single paint job should last for more than five years, so I'm curious why it would have needed to be repainted multiple times in that period.

I'm guessing there's some sort of incompatibility between whatever paint was on their previously and what was used recently. You may have to strip it down to bare wood and start fresh.

 

[gahrajmahal]

Use paint stripper to get back to bare wood and start over.

I disagree with this suggestion. At this point you do not need to introduce new chemicals into the problem. When I strip latex / oil paints I use a heat gun and putty knife, then sand it. I use a respirator while heating the old paint.

If you really can't solve the problem, just add a new thin board to the top.

 

[pcmeiners]

The bubble requires moisture or another compound which creates vapor, and I would surmise it is coming from the wood, I would also bet the "professional" used water based primer, so he does not have to wait for it to dry. Where is the vapor coming from?, possibly dew, or oil contamination on bare wood,just a guess. Strip the area, apply generous heat as suggested or wait a few days, apply a thinned, light coat ( allows primer to breath) of oil base primer, wait a week, then a finish coat; of course no "pro" wants to do this.

 

[BillK]

I would almost bet money that the one with the penny next to it has a screw head or nail under it. Take a pocket knife and peel that spot away and take a look.

 

[bdbecker]

I had the same thing happen after my house was painted last year. Only on one side of the house though. My working theory is that they didn't wait long enough after washing/scraping before they applied the new paint. It was especially humid that day, and it was the last side of the house and I think they were hustling to get it done. After a lot of back and forth and failed 'fixes', they are coming out next month to redo that whole side of the house. Hopefully they get it right this time.

 

[Shiftless]

I had that problem with a horizontal wooden 2x12 cap installed over a short wall round the deck over my garage. Original to the house built in 1950. Using a 3 inch wide power planer, I removed all of the layers of old paint, sanded the wood with a belt sander, soaked the wood with clear penetrating epoxy sealer. Let that dry, prime with oil based primer, and then brushed on 2 coats of semi gloss acrylic paint, following the directions on the can.
That area is completely exposed to sun and rain. Absolutely no bubbling or peeling. It’s been on for more than 10 years. Lots of old nail heads on that job too. (I used a previously damaged set of blades on my planer)

Surface prep is VERY important.

 

[Vintage Veloce]

Well... What I'm learning here is to be sure to use an oil based primer. I don't know what was used in the past.
Also, maybe we should strip the whole sill to bare wood. I'm not sure they went quite that far before.

Besides the bubbling, this stood out to me...a single paint job should last for more than five years, so I'm curious why it would have needed to be repainted multiple times in that period.

Because it bubbles like this.

I'm thinking maybe I strip the whole sill myself, oil based primer following the directions on the can. Wait an extra couple days. Paint.

 

[Bert_]

I had a spot do something similar on a door, probably a 2"x3" spot. I use boiled linseed oil before priming old dry wood. I probably didn't let it dry completely before priming

 

[Spareparts]

Would copper nails do that???

 

[pcmeiners]

Copper nails do not produce vapor.

 

[PCustoms]

Copper nails do not produce vapor.

Do steel nails?

 

[pcmeiners]

No. but nails subject to moisture in wood rust which can cause slight swelling which can be noticable on the paint surface