Teak staircase - painted in dulux satinwood - peels

[ant2]

Wondered if any of you experienced decorators may be able to help.
Backstory:
I had a staircase, all made of teak and stained/oiled.
I had the whole staircase sanded back to bare, the handrail was then oiled/stained, but we had the spindles and all surrounding woodwork painted with Dulux satinwood.

Issue
Each month I would see a tiny bit of paint peel off the bottom of one of the spindles (it was not being knocked as it was the opposite side to the landing spindles) the paint would then flake off and is very noticable as it's dark.
I thought it just hadn't taken in certain sections. I'd sand it back, prime and paint the spot, but more came again several weeks later and this went on for 8 months.
What is weird is all the other paintwork surrounding it had no problems at all and for some reason the upstairs ones are "more" prone to this blistering.

. The decorator's we use are good and couldn't understand why it was happening and is coming back but I am wondering if there is any additional preparation or a better product?

Procedure:
Sanded back to bare, blocker applied (I believe Zinsser bin), it was then primed and then painted with Dulux satin wood.
I've attached some pictures as an example, I managed to actually get a picture of one where you can actually see the flaking of the paint.
There are prior areas that you can see I have touched in prior, ( I didnt' go back to do subsequent coats)

What is odd is that underneath the colouris still dark, but I watched them sand it bare, so would expect the lighter wood colour, which I see if I sand that bit down. I was asking a friend about it and he stated it could be the oils that it was coated with still seeping back out and causing these spots?

Any one have any ideas or suggestions to ensure this doesn't happen again? The decorator is going to come back and sand it all back again (unless it's firmly stuck), block, prime,paint

 

[Chivas69]

If it's showing through that dark I can't see how it was sanded back to light wood and in all honesty I don't think it needed to be sanded down to bare wood as the zinsser primer would block it out anyway before the top coats. Are you sure it hasn't been knocked?

 

[ant2]

indeed. I watched them sand it to bare though. Decorator said the same, they only sand to bare to get a nice flat finish (they use mechanical airless sanders) and the primer is all that's needed for adhesion.
100% is not getting knocked as if you look at the first picture, I am taking pictures of the outside rails that you can only touch (half of) with arms fully extended from the stairs. If you look at the second picture you can it has literally just peeled off.
If it was knocks then i'd have loads on the bottom rails as the kids go down the stairs and I barely see even a nick on those, it's always the top one's, so weird.

They do get wiped for dust , which is when I can see the peeling bits just ping off.

Will see what happens after it's re-done. I can only presume the paint has not stuck for some reason, perhaps there was oil or something still seeping through

 

[Koolpc]

My guess is that its just not adhering.

 

[Chivas69]

The dark bit aren't knots are they?

 

[Alec_t]

Teak contains natural oils, so it's likely those which are causing the problem.

 

[securespark]

If you seal with primers and undercoats that are oil-based, that should stop it, no?

 

[Notch7]

I had a staircase, all made of teak and stained/oiled

Are you sure it was teak?

teak from natural forests got banned many years ago, the only teak available now is plantation grown and it’s about 4x the price of oak


If it is either teak or maybe iroko, both timbers contains high levels of extractives, the best way to deal with them is to wipe off the extractives out of the pores on the surface of the wood with solvent like panel wipe, then paint with a stain blocking primer to fill the pores before they leach out from the timber again.

I would say the problem is a combination of 2 things:

1) extractives on the surface of the wood when bare

2) the spindles have sharp corners so there is minimal adhesion at the corners because the surface tension of liquid paint when wet means sharp edges end up with a thin film thickness - a pencil round of 2mm to 3mm would’ve been better

 

[JohnD]

Aluminium wood primer (which is grey, not silver) can be used on oily wood and knots
You might need to sand off any gloss and clean with white spirit.

Though I agree it is unlikely to be teak.

I got a few offcuts from a boat builder that I use for outdoor work.

 

[opps]

I am a decorator...

I personally only use BIN on knots (and water stains/etc).

I am not a fan of it as a primer on timber. It is quite hard and can be prone to chipping on corners, and your images definitely look like impact chips.

In no way am I maliging your decorators.

I don't understand why they painted everything with BIN first and then applied primer. Primer is for bare wood. Wood painted with BIN is primed by the BIN.

How long did they spend sanding? I would take me over a week just to sand the spindles back to bare wood.

 

[justigator]

Off topic but is that a Roger Oates stair carpet by any chance?