# Hairline Cracks after painting



## parasailing (Feb 6, 2006)

Hi All,

Can somebody tell me what I am doing wrong? Before painting the house, I washed off the mildew with Jomax, powersanded it to a smooth finish and wash the area. Then I waited a week before I started painting the house. I first rolled the wall which has vertical boarding with SW Duration paint but noticed hairline cracks on some boards after letting the paint dry. I followed up by painting a second coat with a brush and it seems to reduce the number of boards that have hairline cracks but some areas still exhibit this problem.

Should I use a primer or some other type of paint instead and see if this fixes the problem? I am wondering if this could be due to wood shrinkage or something. 

Any help would be greatly appreciated.


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## slickshift (Aug 25, 2005)

What's the condition and or age of the wood, and what's on it now?


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## parasailing (Feb 6, 2006)

The condition of the wood is only about 2 1/2 years old as this was a newly built house. I noticed paint starting to crack about a year ago and mildew becoming a big problem in areas where the sun does not hit the area. 

The interesting thing is that the trim wood doesn't seem to have cracks which I presume is due to it being painted with an oil based paint whereas the main body was painted with latex. The original paint was some cheap Kelly Moore stuff.


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## slickshift (Aug 25, 2005)

I'm having trouble picturing your siding and where the cracks are appearing
Are they in an area which might be in need of caulking? Where trim boards meet or similar?
Or is it in the middle of the siding?


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## parasailing (Feb 6, 2006)

The hairline cracks develop on some veritical boarding and vary along each board, some hairline cracks develop on the side some in the middle of the vertical board. After the priming the surface and waiting till the paint dries, I still notice hairline cracks. Upon putting a exterior coat on it, most of the lines disappear but a few lines show up along the vertical boards. 

So basically it looks like whatever I put on it, it doesn't fill in the hairline cracks in the wood. Can somebody recommend me a brand of paint and type that would fill these hairline cracks in the wood since the primer plus exterior coat doesn't seem to be able to take care of this. 

Thanks again!


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## toddscustompainting (Jul 18, 2006)

*Use Peel Bond!!!*

I buy a primer called XIM Peel Bond from Sherwin Williams. It is clear and can go on very thick. I would recommend using a thick nap 3/4" roller to apply it (spray application may be a little nicer but if you aren't familiar then don't attempt). It is absolutely the BEST primer out there to fill in hairline cracks. Email me if you need more information or call a local Sherwin Williams and ask the manager or sales rep about Peel Bond and what it can do for you. Hopefully they sell it and are knowledgeable about it! Good luck!


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## SgtBaldy (Jul 18, 2006)

Most people think of elastomeric paint as just for stucco but we have used it with great success on wood siding as well. It is a thick bodied paint that will stretch over those hairline cracks as the siding expands and contracts. Just make sure you do 2 coats to get on the proper mil thickness.

If I am understanding your problem right that is. Your paint isn't peeling back or lifting is it?


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## parasailing (Feb 6, 2006)

No it is not peeling or lifting after priming and painting. After sanding another test area and removing the old paint, I can see that the hairline cracks in the wood.


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## Jonesey (Jul 24, 2006)

If these are solid boards that join together at the sides, and are real wood, I think I understand the problem. Clear pine, or southern pine, often used in making vertical siding like this is a sappy, unstable wood. It tends to bleed out sap and crack rather badly due to loss of moisture. Often the worst areas are in direct sun exposure. 

To understand how wood reacts to changes is moisture level and temprature, I would suggest going to the Taylor Guitars Website. Bob Taylor has several videos of interest to musicians, and a few of interest to homeowners for this one reason. Wood is a living, breathing thing even after it's cut, dried, and nailed to your home.

http://taylorguitars.com/see-hear/

Click on the Understanding Humidity video for a good explanation of what happens to wood as it gets too dry. As an interesting aside: find the Humidity: the Solution video.

I'm well aware of Kelly-Moore's products, and if the original painter primed and used the 1240 series, the above signs are normal. The 1240 series should be in good condition. No to little chalking, and no flaking

I would suggest two coats of a good quality primer applied by brush over the bare wood areas, and the use of elastomeric caulking in the cracks that have already shown. Unfortunately, you'll be battling this problem for a good long time, but with the use of elastomeric caulking, and two coats of a good top coat, it shouldn't be too severe. I agree with Sgt. Baldy that an elastomeric top-coat with some sheen to it (satin at the very least) will last longer than the average acrylic products, and is well worth the extra investment.

I've seen several old homes with vertical siding still standing up to the elements, but few to none without these hairline cracks in pine vertical lap siding. 

I'm sorry to be the bearer of bad news here, but pine will simply crack. It may have been a better choice to use redwood, wich is a much more stable conifer for a building material, but it is in such low supply as to be economically impractical.


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