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Deck Cleaning Questions and Answers
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Topic starter
10/07/2017 4:52 am
Figure I need to do a back story to properly tell the problem...
- 2 years ago we had a brand new cedar deck built
- 4-5 months later we clean it with the deck brightener kit and stain with TWP
- the next summer its already fading in spots so we pressure spray it and add another coat of TWP... I'm guessing heres where the problem started. Possibly not waiting long enough for it to dry to apply stain?
- within a month, mildew starts rapidly spreading under the stain (i.e. you cant wipe it off)
- deck turns basically black with mildew
- by the end of last summer we decided we had to sand it all off but it was such a rainy season that we couldn't properly finish.
- Forward to This summer. sanded everything off and plan to wait for wood to dry out before staining again. IT's been 7 days and already mildew is forming again
At this point, I'm at a loss on what to do. keep sanding the mildew formations? use a different type of cleaner? we're in MN so its not exceptionally wet but there has been some rain every week. I am half afraid to do anything as I keep thinking the mildew is going to grow under whatever stain we use.
10/07/2017 11:47 am
How did you sand? Anything with metal in it? Typically black spots are mildew or rust. It does look like mildew though. If you stain it in, it will be a repeat of before. We hate to use bleach but sometimes it is a necessary evil as it does kill mildew very well. You would mix it at 1 part to 4 parts water. Apply and let dry. Wait a week or two and see if the mildew comes back or not.
Another tip, the TWP 100 Series does seem to do a little better with mildew prevention over the 1500. Not sure why but this has been our experience with it.
Topic starter
10/07/2017 7:24 pm
Thanks. It's definitely mildew; it spread rapidly last night after the rain shower and is now affecting 4-5 boards. I sprayed the bleach mixture on it this AM and will watch closely.
I assume that if/when we are able to stop the growth and re-stain - a thicker stain option is better? The TWP was semi-transparent.
Fingers crossed that the bleach works.... thank you!
This is a photo of what it looked like by this AM.....
