Last Updated on January 30, 2023 by TWP Help
Moisture Content of Wood When Applying TWP
Whether the wood you are staining is new or more aged, the moisture content is an important factor in the timing of stain application. Applying TWP or most any wood stain for that matter to a wood surface that is still holding too much moisture can result in many problematic issues. Trapping moisture in wood can promote the growth of mold and mildew. A moist and mildew infected environment can lead to wood decay and rot. This should be avoided at all costs. Wood rot will most likely progress to structural damage causing expensive repairs and replacements.
After the wood surface has been cleaned and prepped correctly prior to staining, it should be allowed to air dry for several days depending on the age, condition, and porosity of the wood. A good rule of thumb is to let the surface dry for several days before staining and do not stain if rain is expected. A deck that is mostly shaded may take a day or two longer to dry than a deck that sits in full sun all day. Weather and climate can also be a factor.
To determine the exact moisture content of a wood surface, a moisture meter can be used. They are fairly inexpensive and easy to use. Just probe the wood in several different areas to get an average reading. The moisture content of wood when applying TWP should be 15% or less. A higher moisture content than that may lead to mold and mildew problems and jeopardize the integrity of the stain’s finish and performance.
It is best to be patient and not rush the application process of TWP by applying it to wood that is still too high in moisture. This applies to new wood as well. New wood is often referred to as “green” wood because it has not yet dried out. The moisture content in new wood can be very high even though it may appear dry on the surface. Allowing the new wood to age for 6 months or more may be necessary to achieve the desired moisture content prior to applying TWP stain.
We had an addition of a deck and screened porch in 2015. The decking material is 2×6 KDAT. We had to replace a rail topper last year(it started deteriorating several years ago) and we need to replace a deck board this year. It looks like it is deteriorating from the inside out. I have looked under the deck and I believe I will have more deck boards this next year to replace. My understanding was that KDAT did not have to wait the 3 to 4 months to cure. During the build of the deck and porch was the fall of 2015 major rainy season that year. As soon as they finished the build the next crew came in to paint and stain deck and porch. I have since heard if the KDAT gets wet then it needs to go through the curing process naturally(if that is true that did not happen for the first stain application). I started last year doing my own maintenance. I stripped the original stain and used the restore and renew product. Two days later I applied the TWP stain. We got a major thunderstorm shortly after the application. I reached out to TWP for advice and was told it would eventually cure but will take longer. So this year I cleaned and brightened the deck, waited 2 days and applied 2 coats of wet stain. It has a really great water resistant application, but it looks like there is mold or mildew coming through the stain. My question is can I save this deck or will it require for me to replace?
You can always prep and stain but if your wood is rotting from underneath, then applying TWP on top will not save it from eventually decay.
what would cause rotting from underneath? Is there anything I can do to prevent further damage?
Moisture and or lack of airflow. It cannot be prevented.
I stained my cedar deck yesterday afternoon when I went out this morning I noticed there was dew on the deck and a couple of the boards had a whitish color on them is this from the dew and any way to fix short of stripping and starting over thanks
See if it cures out in a week or so.
I prepped my 6month old pressure treated deck with the Gemini kit, stripped old stain from my 12 year old pergola and applied twp 116 rustic with one coat using a near dry roller and wiping the stain with cotton tshirt material. It came out uneven in color and I need to know what to do next short of hiring a pro to strip and start over.
Post some pictures.
How often should a Michigan deck be stained? Is ponding/puddling water on the boards a sign of non-penetration that determines frequency of treatment or is it best by a set schedule?
Every 2-3 years is normal. Beading water has nothing to do with the need to reapply or not. It is about color fading and visible wear.
TY— Would cleaners/brighteners be followed by a power-washing or used after power-washing?
Use this kit while pressure washing: https://www.twpstain.com/gemini-s-restore-a-deck-cleaner-and-brightener-kit
What are the “solids” percentage content of TWP stains?
https://www.twpstain.com/twp-stain-comparison-reviews-ratings
I checked the moisture content of my covered deck. I have a mix of 38 year old cedar and 1 year old cedar. Cleaned and brightened the deck over 2 weeks ago the moisture meter comes up with a range percentages from 15% to 18%. I have a few lengths of both new and old wood stored in my garage and the both measure at 8% to 10%. Should I wait longer until the content is around 12% ?
15% or lower is okay to stain.
So, I emailed back in July under Best Prep for TWP Stains. I followed instructions to the letter and we hadn’t had rain for days when I applied TWP100. Well, the rains have returned to the Seattle area and it appears I am getting black mold. Needless to say after all the prep work, I am not pleased. I attach photos for your reference.
The railing and picture frame border is western red cedar. The decking is Alaskan White cedar. I did only one coat on the white Cedar as it wasn’t absorbing much stain. The border and rails I did wet on wet.
Please bear in mind, we are just entering the rainy season. I am very concerned how this will progress over the Winter.
What can I do at this point?
The first two photos are the mold on the rail. The third is some spots starting to show on the decking and the last is showing no issues.
Thank you
Hello, the mildew is on “top” of the wood, not “in” the stain. It is not possible for a deck stain to prevent mildew from growing on top of the coating. Mildew can grow on any surface if the conditions merit it. At this point, I would try Wet and Forget. It is a mildew cleaner/preventer. It can be applied on top of the stain and should help remove it and prevent it for a period of time.
How many coats for PT pine that has had no previous stain/sealer? It is about 2 years old. Do you recommend the 1 or “wet on wet application”?
The 2 coats wet on wet.
After prepping, I have a lot of the white “fuzzies” left. I have cleaned/brightened (RAD) twice now with a pressure washer. Do I need to sand before staining?
Yes, lightly sand. The fuzzies will not typically show when stained.
Thanks! I can stain after I sand, right? No need to clean again. I’m running out of warmer and dry weather.
Yes but lightly sand.