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What is Mill Glaze on Decking

What is Mill Glaze on Decking and How to Remove?

When using new wood to repair or construct a deck it is important to know that the wood will not stay new for long. When wood is exposed to sun and rain it quickly turns gray and begins to soften. The wood will have to be protected with a deck stain as soon as it seasons for a few months and dries out.

Before staining a wood deck it should be cleaned. There is some debate as to whether or not new decking needs to be cleaned prior to staining. After all, it may still look new and not be very dirty. The truth is, new decking does need to be cleaned before it can be stained or sealed.

The reason new decking should be cleaned is mainly to remove any mill glaze from the wood. Mill glaze is the glossy like film that develops on milled lumber during the production process. When lumber is being cut, the high speed generated from the lumber planers creates high temperatures. These hot temperatures cause the wood sugars to form a glaze on the surface. This mill glaze is present on most types of newly milled wood like pressure treated pine and cedar.

If the wood is not cleaned to remove mill glaze, it prevents any deck stain or sealer from properly penetrating the wood. This can result in peeling, flaking, poor performance, and premature failure of the stain.

To remove mill glaze from decking, clean the wood with a wood deck cleaner and a light pressure washing or heavy scrubbing. After cleaning, apply a wood brightener to help open the wood pores to accept stain.

If necessary, once the wood dries it can be sanded to remove any remaining mill glaze and to further soften the wood to get better stain penetration. Once mill glaze is cleaned from the wood and it dries, apply a quality deck stain to protect the wood from weather damage.

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25 responses to “What is Mill Glaze on Decking”

  1. Lynn says:

    We just finished building a pressure treated deck. Full sun in northern Virginia. How long should we wait to clean and stain the deck? If we wait three months, we are into November, so is it better to wait until Spring? Would you recommend TWP 100 or TWP 1500? Or something else? Thank you so much.

  2. Janet says:

    We have 20 year old deck in back of our house that was stained with Deckscapes solid acrylic stain 2 years ago. There was some peeling, especially some replacement boards we had put in. After reading your site, I am sure they had the mill finish, because the stain didn't adhere well. I pressure washed 5 weeks ago, and there are 4 or 5 boards with some soft wood that need replacing, plus exposed wood on many others where the stain peeled. We are near Seattle, WA, so there will be rain all Fall, Winter and Spring, but we have a week of sunny weather coming up, with time to prep this weekend.

    Should we wait to replace the soft boards, then prep and stain everything this week? Or should we wait to replace the boards and do those when and if things dry out next summer? What stain do we use for Washington State's VOC requirements? Thanks so much for your help!

    • I would replace now, prep and stain with another solid stain acrylic. Problem is the base coat is still going to be the SW solid and that will continue to peel on the floors. The only way to fix is to remove and that will require sanding it all off which is very hard.

      • Janet says:

        We are sanding. I want to correct my first post–the Sherwin Williams Deckscapes was put on 5 years ago, not 2 years ago, so it held up pretty well. Since we're sanding anyway, we're going to use the TWP 100 oil-based stain. Thanks for your help!

  3. Mark says:

    new PTW deck installed Nov 2014. rough cold snowy winter. Contractor plans to stain/seal this spring, but declined to use cleaner and/or brightener despite numerous recommendations. Any thoughts? Are cleaners and brighteners just gimmicks?

    • No they are not gimmicks. That is ridiculous to say. Washing with water alone can damage your wood extensively if done with too much pressure. Prepping products make it easier, better and gentler for the cleaning process. In addition on new wood they will help to remove the mill glaze and open the grain better for the stain to absorb. Your contractor is not very well versed on the subject. I am sure he does good work but he is missing the value.

  4. marjan says:

    Hi, new redwood deck in California.
    Need to be stained , the price is high from outside contractors, plan to do it by ourselves,running out of money.
    We will use cleaner and brightener by Super deck , the good brand like RDA should be ordered online. The stain that we will use,is Armstrong Clark in Red wood tone.
    Should we use something extra product for removing the mill glaze?
    Any suggestion?

  5. Marsha says:

    I sanded new deck to get off black ink prints and color of wood lightened will it darken back or have I ruined it?

  6. Travis Mattox says:

    We are building a new house with a wraparound porch. We had planned on using a composite decking but a friend works for a building supply company recommended we use western cedar. We would like to stain it in a dark mahogany color not the natural color of the wood. What type of stain would you suggest for this. I have researched composites and I haven't found anything appealing about it.

    • We like Western Red Cedar and that is what most of our clients have. Hard to get it to a dark mahogany color though. You can get it fairly dark brown with TWP in Dark Oak color.

  7. Andy says:

    Hi, I live in Southeast PA and am using new cedar planks. I'm planning to stain with Cabot Australian Timber Oil in Jarrah Brown. Do you have a recommendation on the type of wood cleaner & brightener to use? I've noticed that several products indicate that they're both a cleaner and a brightener, but the above article suggests a 2-step process. What's your recommendation?

  8. Georgeanne says:

    This info was very helpful. I had two decks replaced the summer of 2015 and the stain did not appear to absorb the stain. Shortly after the initial staining I contacted the contractor saying the decks were "sticky". His response was lets check next Spring (2016). Ugg! After one power wash/cleaning in Spring of 2016 they still appeared to have a film on the floor boards. I have spent a bit of time cleaning and brightening them. I now plan to sand them. Irritated that the very competent builders of the decks were not so competent in the staining process. (My decks are made of untreated cedar.)

  9. Doug says:

    I am planning on using premium grade pine KDAT 5/4 decking boards for my new deck. I want to use a clear stain/waterproof product. Rain is expected this weekend and my deck builder insists on installing the decking Sat morning before it starts. Since I"m paying a premium for the KDAT I don't want it to get wet before I seal it so I was planning on sealing the boards prior to installing. I'm also not going to have time to clean & brighten the boards before sealing again due to weather forecast. Not ideal situation but that's where I'm at so my question is this: Is the worse thing about not cleaning the new KDAT boards and sealing prior to installation going to be that I may have to retreat the boards in about a year or less? The other question since I'm sealing before installing is I plan on sealing all sides of the boards. Is this ok?

    • No need to seal all sides. If you do it now, you will have to redo in 9-12 months. Clear sealers will not provide UV protection from graying. You need tint/color in the stain for this. The more you have, the longer it lasts.

      • doug says:

        Actually my wife likes the grey weather look which is what she's hoping for (matches our house better than the stain colors). It's a small deck so no big deal to recoat each year unless the UV eventually destroys the wood. I'm thinking if the cleaning and brightening step is critical before staining and rain is imminent this weekend would it work to install the boards uncoated and then cover with plastic sheeting until I have a week of sunshine to do the cleaning and staining as recommended? I've read it's best to waterproof/stain after boards are put down anyway. True?

  10. Cecile says:

    We had a brand new Cedar deck built in our back yard. The contractor used top-line Olympic stain and applied it via brush. After five months the deck is peeling…parched from the sun. We discovered the deck was not prepped via washing/sanding the Mill Glaze from new wood. What would be the best path to fix and re-stain? i.e. Strip with a product, sand, and can it be re-stained? Do you have a recommendation on stripping product? I really appreciate the advice.

    • Prep with Restore A Deck stain stripper and pressure washing to remove as much as possible. If needed, sand the rest off if the stripper does not remove all. Brighten all when done. Use a penetrating stain after. TWP or Armstrong Clark.

  11. Susan says:

    We're installing a new kdat deck. All info says to clean the mill glaze off first, which means getting it wet. TWP says to wait a full month before applying their stain to kdat wood. My husband insists that we stain immediately and if there is a mill glaze we sand it off. Help!!!

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*This is first and foremost a help site from our experience as wood restoration contractors. All stain and prepping manufacturer directions were followed with our reviews and ratings. We offer no guarantee of similar results. Take inconsideration that wood and deck stain results may differ due to prepping procedures, different wood types, exposure to UV radiation, natural weathering, etc.