Fixing paint bubbles in weatherboard cladding

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timmmay

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#2460110 12-Apr-2020 19:01

Looks similar to mine, but I often got larger bubbles that sometimes had water in them. Whoever painted it used the wrong primer, water based instead of oil based for my timer, only solution was full strip and paint. Get Dulux / Resene rep in for advice, they'll want to see bare wood and the problem areas.

mdf

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#2460434 13-Apr-2020 12:19

That all looks reasonably positive. I was looking for dark brown or red on the back of the bubbling paint - but it actually looks like it is just the top layer peeling off and you still have a reasonably solid layer of paint or primer underneath - doesn't look like it's bubbling back to bare wood (at least in image 1).

I'm a bit concerned about image 2 though - what is going on with all the grains? Sand?

Whereabouts in the country are you - especially proximity to the sea?

Lastman

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#2460478 13-Apr-2020 12:49

Yeah, for some reason, it looks like the paint is not adhering to the old paint layer and is bubbling from sun/heat cycles. I haven’t really experienced this on weatherboard. Most good exterior paints are self priming and stick fairly well. Perhaps it was prep, perhaps paint quality. The simplest solution is just to scrap it down with a spatula like scraper and repaint, filling with a plastic filler if you want a nicer finish. Of course, the bubbling may continue. Taking back to bare wood is a big job.

Remember to catch all scraping etc with a ground sheet. Lead residue is a big problem on old houses.

chonk

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#2460483 13-Apr-2020 12:53

mdf:

That all looks reasonably positive. I was looking for dark brown or red on the back of the bubbling paint - but it actually looks like it is just the top layer peeling off and you still have a reasonably solid layer of paint or primer underneath - doesn't look like it's bubbling back to bare wood (at least in image 1).

I'm a bit concerned about image 2 though - what is going on with all the grains? Sand?

Whereabouts in the country are you - especially proximity to the sea?

Thanks mdf,

Yes it seems to just be peeling off the previous layer of paint and not going back to the wood at all. That's what made be feel more comfortable about the hypothesis of it being painted in direct sunlight previously.

The second image is showing the sanding dust off the boards I was working on above this board and maybe a bit of dirt (I had only washed the boards I was working on).

Something I did wonder about, in pic 2 if you look at the old paint inside the popped bubble, the old paint has these odd lines like wrinkles drawing into the center which I haven't seen before.. I am guessing this is why the new paint had not stuck but I assume that these wrinkles have developed after the new paint was applied.. have you seen this before and any thoughts what is going on there?

I am located in Glendowie, Auckland. About 1.5kms from the water.

Thanks for your help, its much appreciated!

chonk

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#2460495 13-Apr-2020 13:12

Lastman:

Yeah, for some reason, it looks like the paint is not adhering to the old paint layer and is bubbling from sun/heat cycles. I haven’t really experienced this on weatherboard. Most good exterior paints are self priming and stick fairly well. Perhaps it was prep, perhaps paint quality. The simplest solution is just to scrap it down with a spatula like scraper and repaint, filling with a plastic filler if you want a nicer finish. Of course, the bubbling may continue. Taking back to bare wood is a big job.

Remember to catch all scraping etc with a ground sheet. Lead residue is a big problem on old houses.

Thanks Lastman,

Yes I think you are right, ill use the few boards that I am working on as a tester and see if the bubbles reappear in time.. im hoping it was just poor prep and painting in direct sunlight that caused the bubbles.

Appreciate everyone's input, its helped heaps and im feeling good about getting on with the job when the weather improves! :)

mdf

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#2460504 13-Apr-2020 13:20

Acrylic paint shrinks as it dries (water evaporates away). This is very much guessing on my part, but when the current paint was applied, something stopped it from sticking evenly. This caused the wrinkles, including air or moisture bubbles under the paint. When the sun shines it heats up and both softens the paint slightly and causes the bubbles to expand, causing your current issues.

That might be from painting in direct sun (the paint dries before it has a chance to stick) or because the weatherboards weren't cleaned and prepped properly prior to overcoating. Salt will do all sorts of Bad Things to paint, though you're not super coastal.

I'd suggest you'd probably want to give the whole north face a fairly vigorous going over with a scraper. Not to necessarily scrape the paint off, rather to rub loose anything that is going to be a problem later. Nice new coats over the top won't fix problems underneath. As mentioned previously, the only way to be sure about this is to go right back to timber along the whole thing but that is a big job.

I wouldn't be too worried about lead in your circumstances. It has to be quite old and is usually red on the back of the flakes. You can get chips tested for free at Resene. If you do have lead, you must not sand without special precautions. Scraping in to a ground sheet that you then take to the tip is usually the best method.

mdf

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#2460505 13-Apr-2020 13:21

If painting in direct sun, especially in summer, you can use Hot Weather additive.

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chonk

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#2460510 13-Apr-2020 13:28

mdf:

If painting in direct sun, especially in summer, you can use Hot Weather additive.

Thanks, I will definitely use this!

chonk

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#2460516 13-Apr-2020 13:46

mdf:

Acrylic paint shrinks as it dries (water evaporates away). This is very much guessing on my part, but when the current paint was applied, something stopped it from sticking evenly. This caused the wrinkles, including air or moisture bubbles under the paint. When the sun shines it heats up and both softens the paint slightly and causes the bubbles to expand, causing your current issues.

That might be from painting in direct sun (the paint dries before it has a chance to stick) or because the weatherboards weren't cleaned and prepped properly prior to overcoating. Salt will do all sorts of Bad Things to paint, though you're not super coastal.

I'd suggest you'd probably want to give the whole north face a fairly vigorous going over with a scraper. Not to necessarily scrape the paint off, rather to rub loose anything that is going to be a problem later. Nice new coats over the top won't fix problems underneath. As mentioned previously, the only way to be sure about this is to go right back to timber along the whole thing but that is a big job.

I wouldn't be too worried about lead in your circumstances. It has to be quite old and is usually red on the back of the flakes. You can get chips tested for free at Resene. If you do have lead, you must not sand without special precautions. Scraping in to a ground sheet that you then take to the tip is usually the best method.

Thanks mdf, thats really helpful and I will follow your advice about scraping / cleaning up all the north side weatherboards.. luckily for me its not a big house!

I have been acting as if there is lead in the old paint, using respirator and gloves etc., drop cloths and vacuuming up using the shop vac at the end of each day.

Cheers!

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