# Mill glaze



## ExcelPaintingCo

I'm pre-finishing some 5/4" western red cedar decking. The wood got delivered soaking wet with some mold growth in a few areas. I laid it out in the yard and spayed it with cleaner and rinsed. Then I thought I should hit it with brightener (BM brand 6:1) to etch away the mill glaze. After it dried I thought I should test it to be sure.









The board on the left is not sanded, the board on the right was sanded with 80 grit and soaked up the water like a sponge. Moral to the story: always test for mill glaze, and nothing beats sanding to eliminate it.


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## Gough

http://www.fpl.fs.fed.us/documnts/finlines/finishline_mknaebe_2013_007.pdf


:whistling2:


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## ExcelPaintingCo

Gough said:


> http://www.fpl.fs.fed.us/documnts/finlines/finishline_mknaebe_2013_007.pdf :whistling2:


 hmmmm....I wonder what else is preventing the water from penetrating, if not mill glaze. Since its new, un-weathered, cleaned and conditioned. Based on my little test, I'd say that sanding will greatly increase the penetration potential of this wood. I'm a believer!!


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## Gough

Sorry, Excel, I was just being ornery. There's no question that sanding makes a big difference. As the FPL article points out, and updated corroborate, the failures attributed to the mythical "mill glaze" may be due to other factors.


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## ExcelPaintingCo

Gough said:


> Sorry, Excel, I was just being ornery. There's no question that sanding makes a big difference. As the FPL article points out, and updated corroborate, the failures attributed to the mythical "mill glaze" may be due to other factors.


 my nearly equally ornery self will ask you: what else could be causing the left board's lack of penetration? 
I've seen it in the field before. Example: old deck with a few replaced boards. New boards are not weathered and dry. Only new boards fail. This exact phenomenon is currently happening on my own cedar deck. I stripped and sanded it, then replaced a few bad boards. Now a year later, the only failure is on the new (moisture tested, un weathered) boards.


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## Gough

As the FPL article mentioned, they don't even have to be visibly weathered, just a few days is sufficient. 

To me the most damning evidence is the lab's inability to duplicate the condition with dull blades, feed rate, etc.. Clearly, something is causing a problem and sanding helps it. In the long run, sanding is the important part, not so much what we call.


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## ExcelPaintingCo

Gough said:


> As the FPL article mentioned, they don't even have to be visibly weathered, just a few days is sufficient. To me the most damning evidence is the lab's inability to duplicate the condition with dull blades, feed rate, etc.. Clearly, something is causing a problem and sanding helps it. In the long run, sanding is the important part, not so much what we call.


 Maybe one of the mods could be so kind as to change the title of this thread and all other references to mill glaze to "a mysterious condition proven to be nonexistent by the USFS". I don't want to come across as being ignorant!


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## Gough

Maybe we should just refer to it as "kumquat"....


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## Jmayspaint

Gough said:


> http://www.fpl.fs.fed.us/documnts/finlines/finishline_mknaebe_2013_007.pdf
> 
> 
> :whistling2:



What I've always found interesting about that article is they insinuate that "mill glaze" is a myth, then go on to recommend the preparatory steps that we use to deal with it anyway. 

Whether or not mill glaze exists in the strictest sense of the word seems rather a moot point. The phrase has been adopted by the industry as a persuasive measure to convince people that their new wood needs to be prepped before coating. I find it rather handy myself. Many home owners don't really like to hear that there brand new wood needs washing and/or sanding before being coated or stained. "Mill glaze" sounds just scary enough to convince them of the necessity. And it helps that many cleaner and coating systems are labeled in such a way that reinforces the idea. The BM brightner is sold as a mill glaze remover. 

I think of mill glaze as meaning that new, smooth wood is just too non-absorbent to readily accept coatings. Whether or not it's caused by dull saw blades is irrelevant.


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## ExcelPaintingCo

Jmayspaint said:


> What I've always found interesting about that article is they insinuate that "mill glaze" is a myth, then go on to recommend the preparatory steps that we use to deal with it anyway. Whether or not mill glaze exists in the strictest sense of the word seems rather a moot point. The phrase has been adopted by the industry as a persuasive measure to convince people that their new wood needs to be prepped before coating. I find it rather handy myself. Many home owners don't really like to hear that there brand new wood needs washing and/or sanding before being coated or stained. "Mill glaze" sounds just scary enough to convince them of the necessity. And it helps that many cleaner and coating systems are labeled in such a way that reinforces the idea. The BM brightner is sold as a mill glaze remover. I think of mill glaze as meaning that new, smooth wood is just too non-absorbent to readily accept coatings. Whether or not it's caused by dull saw blades is irrelevant.


 Yeah, I thought the brightener would completely take care of it. It might have made the wood slightly more absorbent. Sanding crushed it. 

The logic behind mill glaze makes sense to me. Why wouldn't a high-speed steel blade polish the surface enough to inhibit penetration? It was even visible on the wood, like a sheen. 

Oh well, If I've learned anything on PaintTalk, it's: don't argue with Gough!


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## straight_lines

According to that PDF not only UV exposure you have to be concerned about but if the lumber is stored for a few months before installation then it needs sanding. 

Its no wonder we see so many paint failures that are only a few years old with wood.


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## ExcelPaintingCo

I'm loving my new RO90. This decks going to be nice!


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## stelzerpaintinginc.

ExcelPaintingCo said:


> View attachment 44881
> I'm loving my new RO90. This decks going to be nice!
> 
> View attachment 44889



Don't wanna get off topic too much, but speaking of the RO 90, I'm continuously impressed by how well the delta pad actually sands. I've used almost every vibrating corner sander on the market, and none can remove material like my RO 90. 

I could even use it to, uh, remove mill glaze! See that? Right back on topic.


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## ExcelPaintingCo

I'm getting started staining:








TWP 103-Dark Oak is looking good.


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## PRC

ExcelPaintingCo said:


> I'm getting started staining:
> View attachment 45849
> 
> 
> TWP 103-Dark Oak is looking good.
> 
> View attachment 45857


...........


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## Damon T

I'm digging that dark oak. I've never used that color before. Mostly cedar or natural. Very rich looking.


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## DeanV

We have used Rymar Hickory Bark that is a dark brown also. Nice to know there is another option since Rymar is so expensive. 


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## IHATE_HOMEDEPOT

I believe that the most important thing to understand when coating decks is that you are painting trees. Almost every single board is unique. Moisture content is equally as important.


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## ExcelPaintingCo

The staining is complete. I used a tiny bit over 2 gallons to cover 1200 linear feet of material. I only sanded the tops. The bottoms got one coat and the tops and sides got 2 coats wet-over-wet with about 20-30 minutes to penetrate between coats. As per the directions on the can. 









Here's another illustration of how sanding aids in penetration:











The board on the left is an un-sanded underside and the board in the right is a sanded top after one coat. The darker color means more material penetrated.


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## stelzerpaintinginc.

ExcelPaintingCo said:


> The staining is complete. I used a tiny bit over 2 gallons to cover 1200 linear feet of material. I only sanded the tops. The bottoms got one coat and the tops and sides got 2 coats wet-over-wet with about 20-30 minutes to penetrate between coats. As per the directions on the can.
> 
> View attachment 46177
> 
> 
> Here's another illustration of how sanding aids in penetration:
> 
> 
> 
> View attachment 46193
> 
> 
> The board on the left is an un-sanded underside and the board in the right is a sanded top after one coat. The darker color means more material penetrated.



Great info all around Excel. I might add that sanding DOES aid in penetration, provided 80 grit or a rougher grit are used. However, if the wood is pre-sanded with much higher, (finer), grit than 80-100, the stain will not be able to penetrate as deeply. 

I'm 100% sure you already know this. I only mentioned it for any noobs who read this thread.


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## ExcelPaintingCo

stelzerpaintinginc. said:


> Great info all around Excel. I might add that sanding DOES aid in penetration, provided 80 grit or a rougher grit are used. However, if the wood is pre-sanded with much higher, (finer), grit than 80-100, the stain will not be able to penetrate as deeply. I'm 100% sure you already know this. I only mentioned it for any noobs who read this thread.


 Good point. For the record, I did mention 80 grit in the OP.


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## PNW Painter

This post is a great reminder about mill glaze. Thanks!


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## ExcelPaintingCo

An after shot of the mill glaze free, pre-finished cedar deck:


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## doctors11

Great job! What did you use for spacers?


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## ExcelPaintingCo

doctors11 said:


> Great job! What did you use for spacers?


 I don't know. I didn't partake in the construction process.


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