Another yakisugi / burnt siding question

[forrestM]

I'm planning to charr my 1/2"x6" poplar clapboard siding. I wanted to just use natural oil, but you can't keep it from mildewing in Virginia, even with mildewcide it seems. The black look will be bold, but from what I've read it should last for a long time, and there will be nowhere for any mildew to grow. 

It seems the traditional method only burns the face side, with the back left natural - to me that seems like painting and priming only one side?

And it seems like you get a huge moisture differential and might be prone to cupping. 

I asked one company about it and they even burn the bark side, so the bark side is then facing out - and what I've always thought to be the rule was to have the heart side facing out for best durability, and also because any cupping would cause the laps to move back towards the house and make a tighter seal. 

I am wondering if I would get into trouble charring all 4 sides? Does that somehow seal moisture in side the plank? The wood I'm using is poplar kiln dried to usually a little under 12 percent. To me it seems easy enough and better practice to charr all four sides, but don't want to somehow cause it to rot from the inside out. 

Thought @GeneWengert-WoodDoc miggt have some science for me?

[Broncman]

I am getting ready to mill some poplar for siding. I will not be burning mine,  but I watched one guy use a circular saw with a guide and cut relief grooves in the back to help prevent cupping.

He cut 2 grooves about a 3/16 or so deep the length of the board on the back side.

He claimed it helped stop cupping. 

[beenthere]

Burning will not give you much more than coloring the wood a burnt color.

Doubt you will gain much protection otherwise. 

[Don P]

Outta the muck and into the fire  .

[GeneWengert-WoodDoc]

You certainly want to have a waterproof finish, as water accelerates weathering.  One possible finish to consider is 

BEHR PREMIUM® SEMI-TRANSPARENT WATERPROOFING STAIN & SEALER NO. 5077

You also would likely benefit from a finish that blocks UV.  UV accelerates weathering.  One example is 

 Flood FLD520 Cedar CWF-UV Exterior Clear Wood Finish

[Don P]

This came in email from ALSC a few days ago;

PACIFIC LUMBER INSPECTION BUREAU (PLIB) SUBMISSION FOR THE REVISION OF "PROPOSAL FOR THE SAMPLING AND TESTING OF SUGI (CRYPTOMERIA JAPONICA) FROM THE COUNTRY OF JAPAN FOR THE ESTABLISHMENT OF ALLOWABLE PROPERTIES FOR NGR GRADES" The Board of Review will consider the revision of "Proposal for the Sampling and Testing of Sugi (Cryptomeria japonica) from the Country of Japan for the Establishment of Allowable Properties for NGR Grades" dated February 7, 2023