What is Mill Glaze on Decking 4.9/5 (26)

by Deck Stain Help

Updated February 2020

Mill Glaze on Wood Decks

DeckStainHelp.com has become the Internet’s go-to site for professional wood deck staining tips. We often hear about mill glaze on new wood surfaces. We offer tips on how to remove pesky mill glaze and prep new wood for an ideal surface. We encourage discussion on our site, so feel free to leave a comment below.


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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John
John

Hi. I am installing a new t&g porch dog fir in Seattle. I didn’t account for mill glaze and had actually never heard of it. Well, now about half the wood has the spots everywhere and that just isn’t going to fly with person I am installing it for. I used Daly’s Deck Stain (which was fairly popular in the PNW) and the rep there told me I didn’t need any conditioner or to do anything for prep since it was new wood. All six sides are already stained and the plan was to get it and stained in one of our last windows before we have rain for the next 6 months. How can I fix this? Thanks for you help.

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Rene
Rene

Is weathering and cleaning and brightening to remove mill glaze for stain prep necessary both for new cedar vertical tongue in groove siding as well as cedar planks for decking?

Rene
Rene

Can mill glaze be removed from new cedar siding just by sanding, without using wood cleaner and brightener?

cynthia
cynthia

DID I RUIN OUR NEW DECK?! Went to prep newly installed deck (4 months ago) for staining. Did water test and drops seemed to absorbed so I thought wood wasn’t treated. Washed/scrubbed with a Bob Villa recommended ‘natural cleaner’ of Oxyclean, some borax, and dish-soap. As I scrubbed, gunky grayish lumps started appearing in my brush and the boards became very slippery. I clearly see some ‘finish’ coming off-now the boards are unevenly free of this ‘stuff’. Should I just keep scrubbing and rinsing to get it all off? Is it, indeed, mill glaze?

Norm
Norm

I have new cedar decking. Installed 5 weeks ago.
i live in Seattle Washington, It had rained on it about 10 days ago, but otherwise dry and tempurture in 80s.
Read various website about how to stain and all talked about mil glaze.
Board are very smooth and I suspect they must have mil glaze on them.
Didn’t even bother to do the water test on the board.
I bought Lowe’s Wood prep that has Oxalic acid (said on label that it removes mil glaze).
I sprayed it on, vigorously prushed the wet treated boards (doing 4 boards at a time) to make sure it really does a good job. let it sit on the wood (keeping it wet by apply a little more solution) for about 10 min, then rinse it off.

Now I’m ready to put the stain this weekend, I pure a little water (about 1 oz.) on one of the deck boards.
Water just just sits on the top of the wood.
It took about 5 min for water to get soaked into the wood.
Is that acceptable?

How long should it take for the water to get soaked in?
I figured if the wood is ready for staining, it would soak in the water within first 10 seconds.
That didn’t happen. It took 5 min.
On various sites that talk about this and all these questions here, no one mentioned how fast should the water get soaked into the wood.

Should I

1. Go ahead and stain the deck (5 min is fast enough)
2. Do another treatment of deck prep, maybe use another product.
3. Sand the deck since wood prep didn’t open up the wood enough.
4. Wait another month to let is weather so me more.
5. All the above
6. (insert your option here)

Thanks,
Norm

Harold J Hovel
Harold J Hovel

We are building a screened-in porch. Floor is Trex so no staining. The supports are pressure-treated 6×6 pine and the horizontal railings are also pressure-treated pine 2×4. There are darker and lighter areas on the wood which I can’t tell if they are dirt, oxidation, or mill glaze. Sanding leaves stripes of darker surface where the sandpaper didn’t reach (since the surfaces are not completely flat). Question is – how to tell if those areas are dirt or mill glaze or weathering discoloration. Can a person stain over the wood even with the discoloration areas? Is it essential to do the cleaning and brightening prep after allowing time for the wood to “dry” or do I have to sand away the discolored areas? Thank you.

evefc
evefc

We had floor and handrail deck boards replaced over 1 year ago. Installers never power washed or sanded to remove mill glaze. The guy who will be staining now did a very light power wash, saying it should be light because its new wood and that it’s ok to just stain without sanding. Will the mill glaze have disappeared by now sitting in the sun all that time? Also, water doesn’t “bead up” but sort of lies on top in a sheet of water.

Ryan
Ryan

I have a smooth cedar deck that is about 1 year old. After I let it cure, I powerwashed it thoroughly, let it dry, then applied one-time wood stain. It looked great right after applying. Then the next day I looked out and saw green discolored spots everywhere which I later found out was due to the mill glaze. This was last Summer. Now that Spring is here, this is my next project. They kindly sent me 2 gallons of stain to re-do my deck. I was instructed to sand the old stain off, then apply their stain and sealer remover to get the rest of it up along with fixing the mill glaze issue. Then power wash, let dry, and re-stain. Since this is quite time consuming and their stain is very expensive, I want to get this right. Can you confirm if I should sand, then apply the remover or should I do this in the opposite order. Any help is appreciated! Thanks!

Jasonk
Jasonk

I have brand new tongue and groove cedar I’m using for a Seiter ceiling. They are one by sixes. One side is rough one side is smooth from the mill. This sequence of cleaning the word and sending I am a little confused. Do I give it a light sanding with my orbital sander and then scrub it with a wood cleaner and wash it. Or do I scrub it with the wood cleaner now let it dry and then send it and then just brush off The dust or does it require another washing after the sanding. And what grit sandpaper would you use?

Carol
Carol

I am trying to repair / replace rotted boards on a handicap ramp for my mom. I purchased pine deck boards and not knowing anything about mill glaze, I wiped it “clean” and applied BEHR PREMIUM® Solid Color Waterproofing Stain & Sealer. While searching for something else, I just came across this page on mill glaze. Ohhh, never heard of that! So, now my question is – what do I do? I ‘thought’ I was going great at it—- applied the Behr product to all 4 sides. Two coats. So, now, what to do? Thanks for your help.

Tyrone
Tyrone

I have a new deck that came with my house purchase. It has been weathering for 1.5 years due to life events and rain. I am trying to stain deck this 2017 Labor Day weekend and came across your mill glaze advice. If I sand the entire deck to remove mill glaze and green mill marks/stamps, do I need to still wait 1 to 4 months? The entire deck should be even right?
I was going to do the following order 1. Powerwash 2. Use deck cleaner 3. Dry for a day 4. Sand entire deck 5. Stain
Is this okay for new decks?

Darren
Darren

I put pine plank siding on my barn in the snow of December. It has rained and snowed and been 95 degrees on the bare, untreated wood for 7 months. Do I still need to worryworry about mill glaze?

Steve MacMeeken
Steve MacMeeken

I used an exterior water based stain from Sherwin Williams to stain some new cedar 1×6 tongue and groove cedar boards under a protected patio and some cedar beams it fished eyed on me and even started to run in areas making drip marks way after the stain was applied.
Sherwin Williams wants me to power wash then chemically treat the surfaces using their product called “Resolve” Appling it with a pump sprayer. How long should I wait before re-staining?

Katherine Delapas
Katherine Delapas

Is it still necessary to open the pores when you are using solid color stain?

Susan
Susan

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!!!

Cecile
Cecile

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.

Doug
Doug

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?

Georgeanne
Georgeanne

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.)

Andy
Andy

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?

Travis Mattox
Travis Mattox

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.

Marsha
Marsha

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

marjan
marjan

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?
Thanks

Mark
Mark

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?

Janet
Janet

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!

Lynn
Lynn

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.