Exterior Paint Failure ?

[Willa]

I made a fence from antique wood doors, that were previously painted. There's a topic in here with pics somewhere about my fence.

The doors had come from a smoker's house. They were all painted with an old oil based paint, who knows when, on top of varnish or shellac. I scrubbed them all with TSP, then applied two coats of a solvent based alkyd paint, which I added a little Penetrol to.

Since I painted them all black, I think one aspect of the paint failure was thermal. After the first winter, I had paint failure on the back side. By paint failure I mean that large air filled blisters had formed, and some areas had curled up, exposing the shellac or varnish layer. I scraped off whatever was loose, then reapplied the same oil based paint. This stayed put, for the most part.

On the front side, over this winter, I noticed many areas where the paint was curling, cracked or loose, as well as some blistering. In all areas the paint that was loose was the black layer, firmly adhered to the white layer below, peeling from the varnished layer on the bottom.

Is the lack of adhesion due to the varnished or shellacked layer below ? Is the only remedy to remove ALL the paint, sand well, apply an adhesion primer, then paint over that ?

I heatstripped one door, which took about an hour and half. Stripping them all (front only) won't be fun but is doable ?

Fence when it was a few months old:

freshfence.jpeg (1.66 MiB) Viewed 737 times

Back of fence showing paint loss, after winter:

fenceback.jpeg (622.55 KiB) Viewed 737 times

[heartwood]

sorry you're having this issue...
the failure has somewhat of a uniform look--the panels seem to be holding up, from what I can see, but the stiles and rails exhibit failure...
i'm not a supporter of using TPS as it's damaging to the environment and cleaners such as simple green or vinegar and dish soap may offer the same results...it's possible the TSP affected the existing paint's adhesion...did you rinse well? sand prior to painting? did you prime? those are all things that could affect the outcome...

I look forward to reading other's feedback.....
......jade

[Willa]

sorry you're having this issue...
the failure has somewhat of a uniform look--the panels seem to be holding up, from what I can see, but the stiles and rails exhibit failure...
i'm not a supporter of using TPS as it's damaging to the environment and cleaners such as simple green or vinegar and dish soap may offer the same results...it's possible the TSP affected the existing paint's adhesion...did you rinse well? sand prior to painting? did you prime? those are all things that could affect the outcome...

I look forward to reading other's feedback.....
......jade

The condition of the doors is fine - no rotten wood or significant loosening of joints. The paint is peeling off the very lowest layer which appears to be shellac or varnish. My paint adhered well to the old oil paint that was already on the doors. The issue is the lack of bond between the deepest layer and the paint on top of it. The areas that had the most intense sun had the most paint failure. I assume the black paint made the doors hotter than a light colored paint would. Winters here can be -20F and summers in the 90's plus lots of humidity so that is a pretty great range on temperature.

Is the only solution to get paint to adhere to the varnished layer is to strip off all loose paint and as much varnish/shellac below ?

[Manalto]

The environmental risk of TSP is its presence in the waterways. In Willa's situation, that is unlikely to happen unless she dumps leftover mixture down the drain. Trisodium phosphate is strongly alkaline, so it's best to keep it away from plants (eyes, skin, etc.). You can also partially neutralize it before dumping with some white vinegar.

[phil]

shellac melts at a really low temperature. for example my kitchen table has a shellac finish. If I leave a cup of hot coffee on it and go away Ill return to it being stuck down. It is because of the low melting temp.
put black paint on top and set it in the sun, Yea it'll fail quickly from the heat. Shellac isn't for outdoor use.

Phil

[GibsonGM]

1)Look in the hardware for a "TSP" (made by the company USG, as most TSP sold in the US was/is)...look to see if it says "TSP Free". Use it. It has no phosphates, the nasty compound that really, nobody carries anymore (for 10, 15 yrs now). No real TSP around here, anyway. As Manalto stated, it is a runoff hazard, sure - but is often found in food, LOL! Bad for the plants. Tho some places talk about using it everywhere, it's more for taking off wallpaper paste than anything else. That is the only use I have for it.

I hear you on the nicotine....for that....SHELLAC. I don't even clean it anymore; it's nasty and cleaning it does little anyway, it becomes a condition in the contract. See below re shellac outdoors.

2) phil has it - doors were probably first treated with a shellac of some form, for interior use. Then we pop them outdoors....unh unh. The heat isn't helping, but moisture, as always, is the real killer. It IS possible to stain block with shellac exterior if you "sandwich" it.....clean reasonably well, dry, prime, shellac knots, then topcoat. In this case...I'm sorry Willa, I think you need to 'take it down' as best you can, IF you want to try over. Strip, TSP (free) if you like, dry, prime with alkyd, top coat. End grain on the stiles might wick moisture no matter how well you try to seal them, causing expansion and popping of paint (?)...

I LOVE the door/fence idea, but I think maybe the movement of the panels (and they WILL move independently) could be a factor here along with end grain absorption....hate to think of you doing it ALL over just for it to happen again...one time I'd wish they made them out of plastic so you could be sure they'd be ok in the environment!

[Willa]

1)Look in the hardware for a "TSP" (made by the company USG, as most TSP sold in the US was/is)...look to see if it says "TSP Free".

I'm in Canada so what I can get here may be different. I have no desire to RE-TSP the doors. The TSP scrub was to remove as much nicotine and filth as I could from the doors before I painted them. This worked as my paint definitely bonded to the old paint. It is the surface below the paint that is the issue.

2) phil has it - doors were probably first treated with a shellac of some form, for interior use.

(No - I said that.)

In this case...I'm sorry Willa, I think you need to 'take it down' as best you can, IF you want to try over.

My (lazy ?) plan is to strip one door completely, sand that the best I can, use an adhesion primer then paint with the same black oil paint. This will be my test door - and I'll wait and watch what happens through the summer and next winter. If the fresh paint stays stuck, then I will strip and redo the rest of the doors next summer. I will touch up all the areas where the paint has fallen off. I did this last year on the back and unless you are super close to the doors this looks acceptable. Before the fence was assembled I made sure that the edges and top and bottom of the doors were painted, to try to minimize areas where water can enter the end grain. However - the carpenter did have to trim a couple and I also did not consider the sharpness of bird feet.

I LOVE the door/fence idea, but I think maybe the movement of the panels (and they WILL move independently) could be a factor here along with end grain absorption....hate to think of you doing it ALL over just for it to happen again...one time I'd wish they made them out of plastic so you could be sure they'd be ok in the environment!

The areas that are the worst for paint loss vary somewhat which I guess is dependent on the amount of direct sun they get at what time of day. The paint loss on the BACK of the doors was much less this year than the first year. It was surprisingly bad after the first winter. It may be that whoever painted on top of the varnish/shellac finish did not prep that surface properly so that may be affecting the adhesion, too ?

Besides the unhappy paint adhesion the fence has stayed sound otherwise?

[Willa]

Also - I suspect the doors are pine, so they may have been faux grained using whatever finishes were current at the time they were installed. They came from a local farmhouse that wasn't a fancy place. It may have always been home to super smokers, too, which may have interfered with the varnish/paint layer ? Whoever lived with painted doors REALLY smoked.

[GibsonGM]

Well, you know - there are no guarantees in this, unfortunately...the doors are a natural material; the parts move independently of each other, and were intended to be used indoors. You can kind of tell they've been doing that from the 'after' pic. As a painter, I can say: a little water goes a LONG way! Sun will bake one side, contracting it, and the internal moisture will expand the other. I'd NEVER take a job refinishing doors for that use, ha ha - not with any guarantees. As with the floor of a deck, a stain manufacturer generally says this will require 'yearly re-application'...

The painter's creed is basically: dry out, then scrape, sand, prime, paint. And hope for better luck. Sanding WILL remove nicotine, at any rate.

[Willa]

As a painter, I can say: a little water goes a LONG way! Sun will bake one side, contracting it, and the internal moisture will expand the other. I'd NEVER take a job refinishing doors for that use, ha ha - not with any guarantees. As with the floor of a deck, a stain manufacturer generally says this will require 'yearly re-application'...

The painter's creed is basically: dry out, then scrape, sand, prime, paint. And hope for better luck. Sanding WILL remove nicotine, at any rate.

The doors had been removed from the house - which I thnk had been vacant for a long time, was going to be demolished - then they sat in a barn or garage for some time. I cleaned them up and painted them in the late fall - November - then they went up in December. There was no window of time for them to sit in the sun or a warm house to dry out, IF they were damp. They didn't feel damp, no wet bottoms, etc ?

When I painted them, their paint was about 95% intact and I made sure to scrape off loose paint, and sand the edges. I fretted about paint failure, but hoped for the best.

Because this paint situation is, well, odd, it seemed pointless to ask at the local BM store as this would probably be an unknown. I searched for answers online, but again - most people don't have previously varnished now painted wood outdoors. I used the same hardware store paint, thinned with Penetrol, to paint all my fence pickets - and they have weathered perfectly - with no blistering or paint loss anywhere over the last winter.

Now it's suddenly cold and wet again - so I will have to wait for another period of dry sunny weather to test my theory/re-paint.