Hello to all!
This is my first time posting here and I’m hoping someone will be able to offer some insight. We recently had our home re-sided with red cedar shingles, pre-primed and back primed. They have since received their final coat of paint and after a few weeks we noticed a dark, oily, substance appearing on the shingles in a number of areas. What is this and how can we get rid of it?!?!? Is this sap leaking through the shingles? The substance is fluid (meaning you can smear it) when there is a lot of moisture in the air in the AM, but dries up in the afternoon. HELP!
Mike
Replies
What was the topcoat material?
David,
The contractor used an exterior latex paint for the topcoat (red color) over the pre-primed shingle siding. I don't know if the staining is due to sap surfacting from the shingles? Degradation of the red paint color (black color mixed in to create the red is somehow separating itself). This is a far-fetched notion, I know, but we're at a total loss!
Thanks,
Mike
About the color separating: I used a heavy bodied brown stain on a house once and black kept "boiling" to the surface and spreading--looked like when you put instant coffee in water; the black was like the coffee. Very strange and annoying. The black did sort of look greasy and it looked like the brown was being "repelled" in those spots, so at first I thought that pine tree sap (there were lots of pines around this house) was on the claps under the stain, but I'm pretty sure the dealer just didn't mix the stain long enough. It seemed to sort of blend when it dried though, in my case. May be different on red, or may not be what I'm describing. Could it be oil from the cedar coming through? That was my first thought. You could try a stain blocking primer on one spot and see if it stops it. (If the bleach idea that someone else posted doesn't work.)
I have used Teal Cedar WRC pre-stained shakes once, and the finish is oil. Latex paint would not work over that particular finish. When you say pre-primed, what exactly is the primer and did your painter make 100% sure that his topcoat was compatible? I'd say call the company that supplied the shingles and talk to their paint chemist about it. Mildew is a possibility but it's easy to recognize. I'm suspecting some unhappy interaction between the two finishes.
Good chance you are seeing mildew. Are there any trees or bushes within 20 feet or so? Is it more predominant on sides that don't get much sun? A mildewicide can be added to paints and stains but it doesn't last forever. Spray a little chlorox on it. If it is mildew it will be killed by the chlorox and run off. To keep it away you will have to wash the house periodically with a mixture of TSP, chlorox and water. Not the best thing for dark red paint but you can't stop Mother Nature, you can only deal with her and try to fight back.
Beat it to fit / Paint it to match
Here was my first thought - red cedar and redwoods have tannins that are hard to cover and paint companies make special primers to seal them in when painting those woods. I believe that for some reason it is a greater problem on exterior surfaces.
So I was fgoing to ask what product you used for the priming and sealing and if the lable pronounced it specifically for those woods.
But the fact that this seems to come on go makes it a mystery to me.. Tannin stains tend to remain and harden, in my experience, anyway.
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Thanks for everyone's response - you've all been a great help!
I'm almost positive it's not mildew as the only vegetation near the house are some bushes in the front and the problem is occuring almost everywhere but there. These greasy stains started appearing about 2-3 weeks after the final coat of paint was applied. I'm leaning toward the explanation that there is some sort of reaction between the pre-primed shingles and the paint. The only other possibility is tannin. I'm going to try and take some digital pics tomorrow and post them. I've spoken with the GC again and the supplier will be contacted Monday. Thanks!!!
It will be interesting to see what the painter thinks it is.
Can't see any profile info on you.
Where abouts are you and what were the temps and humdity like when this was painted and since then.
Any condensation or frost on the house?
Which/whose latex product was applied?
Sprayed, brushed or both?
Knowledge is power, but only if applied in a timely fashion.
Goldhiller,
My first post was yesterday-I'll have to set up my profile.
I live in Massachusetts. The temperature was in the mid 70's when this first started a few weeks ago with temperatures dropping to the low 60's at night. There was considerable condensation on the house first thing in the morning and the "geasy" substance could be smeared easily. As temps picked up the substance dried. The paint for the body of the house was sprayed.
Any thoughts?
Thanks,
Mike
I'm definitely suspecting surfactant leaching.
Not that uncommon of an occurrence under the moist conditions you describe.
Been there, done that.
IME, the material will eventually set up hard, usually within a couple days and can then be painted over with a thin coat via the brush to hide it from view. This spot touch-up may or may not be a viable solution for you. Depends on just how much of it there is.
Or you could try washing it off or just letting it weather away.
http://www.paintquality.com/failures/exterior/surfactant.htm
Knowledge is power, but only if applied in a timely fashion.
Hey Mike
Welcome!
I installed red cedar handsplits on my circa:1680 house less than a year ago.
I'm on Long Island.
I primed the face with a Benny Moore fast drying oil primer.
I then painted over that with BM soft gloss cottage red (two top coats).
Its been about two three weeks and I see no signs of tannins appearing.
You may want to give the BM tech rep a call as I did.
They even came to my house before I started.
One other thing I did was before I painted, I sprayed on a mix of one part bleach to three parts water.
Left it on for ten minutes or so making sure it stayed wet then power washed it off.
Checked the walls with a moisture meter a few days later till I knew it was dead dry.
Be wall.....I mean well : )
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As temps picked up the substance dried
Did it evaporate or leave a dry residue after drying. If a residue, what type?
Did you ever get an answer from the guy who painted it?