Steam Chamber

[YellowHammer]

Has anyone set up or used a steam chamber for walnut?  For the big outfits down here, at least two have built huge "steamers" for coloring and flattening walnut and cherry.  They look just like big dedicated enclosures with steam being injected.
Thanks,
YH 

[Southside]

Will this help you?

https://www.youtube.com/watch?v=ae50P_ajLxA&feature=emb_logo

:D

[YellowHammer]

Yep, where do I get one?  

[GeneWengert-WoodDoc]

You will see three inexpensive steamers for walnut in DRING EASTERN HARDWOOD LUMBER, USDA Ag. handbook 528.  Written by McMillen and Wengert in 1976.  

[K-Guy]

I read an article in a woodworking magazine a few years ago talking about walnut fresh, aged and steamed, it warned about the fact that steamed walnut does darken but not the same as aged walnut. It is a matter of choice if you like it or not but it doesn't get the hue as aged wood.

[btulloh]

YH, you may want to quiz your customers about the steamed walnut. Personally, I hate it and I will drive a long way to get walnut that hasn't seen any steam.  I guess there's a case for it or wouldn't be so prevalent in the retail trade, but I really don't care for the color change.  I guess if I needed a lot and was concerned with uniformity of tone, I may be forced to go that direction, but I'd rather sort through and match the non-steamed stuff.  It is true that walnut never really reaches it's real color for many years though.  I suppose there's a lot of different opinions out there about the steamed walnut - maybe most people want it or don't know the difference.  Sounds like you've got a lot of walnut customers you can survey.  

[Glenn1]

Please don't tell me that you're moving to the dark side...steamed walnut...never!

[Southside]

That explains it - Got a call today from Alabama, thought it was a joke, all I could hear was deep breathing and something along the lines of "your father" and "ruling the galaxy".... :D

[Andries]

Ok, I'll 'fess up . . .  that was me on the phone.
 

[Andries]

 . .  and while we're talkin' about steam, you should feel free to send some of that our way. 
@goose63 and I would 'preciate it! 😧😧😨😧😧

[GeneWengert-WoodDoc]

There are two critical requirements for steaming walnut.

First, you must use 100% RH at all times, including the initial heating.  Anything less than that and you will get drying, which stops the color change.

Second, you need roughly 200 F.  

Did you know that the fiber saturation point (FSP) for wood at room temperature, or so, is 28% to 30% MC?  Did you know that when the wood is heated to 212 F, the FSP is dropped to around 22% MC?  This drop means shrinkage of the cell wall.  Plus water moves out of the wall into the cell cavity.  The hotter you go over 205 F, the greater this shrinkage effect.  It is easy to check walnut in a poor steamer

Did you know that medium pressure steam at 10 psi pressure has a temperature of 239 F?  And 15 psi is 250F?  When this steam is put into a chamber like a steamer, the pressure drops to atmospheric, but the heat stays with the steam.  This means that the wood surface and slightly below is exposed to 239 F.  The FSP drops even further, and the humidity will not be 100% RH.  The color change will be poor and some checking, surface and interior, as well as end, is likely.  For this reason, many people who try steaming find it does not work...they did not get the correct conditions within a hour after starting.  You need enough steam.  You also need to boil the steam through water, which allows the water to absorb the extra heat and achieve 100% RH.  If you look at the three plans in DRYING EASTERN HARDWOOD LUMBER, you will see the trough, which must be kept full of water.


So, without the proper steaming, lots of people, including researchers, come up with false information about steaming walnut.

[YellowHammer]

 



Steamed or unsteamed?  

I confess, I do want to rule the galaxy, but I'm a little rusty with my lightsaber, so I guess that won't happen. But that is a real cool look, Andries, I may have to get me one of those rigs.  

So here's a few things I've learned, because I've been selling both (Arghh) steamed and unsteamed walnut side by side in the rack for a couple years.  Yes, I tell customers the differences so they know what they are buying.  

Here's my observations, so far.
With unsteamed walnut, it has a richer color, a little purple, and it must be edged heavily to remove the sapwood.  Sapwood snobs, as WDH calls them, are hard to please.  So I trim all the sapwood off walnut, and sell the sapwood boards as "Edge Walnut" at $6 per bdft. Edge walnut sells well, but at a 40% lower price than my edged, full heart walnut.  

Unsteamed walnut can have a lot of stress, and bow in boards is common and must be removed by mechanical means or.....heat.  Basically steam straightening, but at a lower temp because I don't have any steam.  However, I have been able to straighten pallets of bowed wanut and cherry if I go into a "Super Sterilization" cycle in my DH kiln.

Many of the professional high volume walnut custmers prefer steamed walnut, as it's much easier to match colors with existing furniture, and it has a more brown rather than purple color.  It also doesn't turn as dark with a finish and steaming takes out much of any residual stress in the boards.

Also, for most walnut the higher grade boards are sidewood, and knots appear as the boards are cut closer to the pith.  So grade goes down as heartwood color goes up.  

So steaming has several advantages over ussteamed walnut.  It has less stress, resulting in flatter boards, utilizes sapwood soôrecovers more usable wood from logs, has a lighter color tone and is preferred by many of the commercial users here.  

Which type do I sell more of being both are in the rack side by side? Steamed.  My higher volume customers just don't care, or actually prefer steamed.  

I've got 5,000 bdft drying in my kilns right now, so I still am sawing and drying a decent amount of wanut.  Unfortunatelty,
I have to buy steamed walnut for my steamed customers, so I want to try to make my own.  Those are good references Gene, I'm going through them.
 

[Southside]

So are you just blowing off steam here over having to buy walnut for your customer base? :D

[goose63]

. .  and while we're talkin' about steam, you should feel free to send some of that our way.
@goose63 and I would 'preciate it! 😧😧😨😧😧

Yes we would 22 below to night but just think 40 or so days the warm up will be here :new_year:

[YellowHammer]

I'm buying steamed walnut and selling it, as well as our unsteamed.  I'm getting my steamed walnut from various places, but the last load came from Missouri.  There are very few, as in almost none, who can match our grade quality and that's another reason we are selling so much of it, because most of our commercial customers have been burned by others, and being sold low grade walnut, sold on "Walnut Rules" which drops the grade in one notch.  So I can't dry enough to keep up with the demand for our premium unsteamed walnut, (both my Nyle kilns are full of walnut now) and am struggling to keep up with the demand for steamed walnut, as well.  Since I can't produce steamed walnut, I was turning high dollar customers away.  Since I'm in business to make money, I found a couple places that can produce premium grade steamed walnut, I buy from them, do the secondary processing if necessary, and then resell it very rapidly.

So I'm thinking of getting another kiln, and maybe it's a steam cycle this time.  Then I could produce both steamed and unsteamed walnut.  There are a lot of customers out there who want steamed walnut.  There are also a lot of customers who only want unsteamed.  They can stop at Hobby Hardwood and get a premium grade of either.  

This is a piece of 8/4 steamed walnut, high grade, no knots, flat as a pancake, and edged one side.  I guarantee you this board will be sold tomorrow, along with many of its brothers.  Selling price, $15 per bdft.  

Right next to it will be a pallet of unsteamed 8/4 of equally high grade.  Selling price, $15 per bdft.  Customers choice.  


  

[btulloh]

Choice - best of both worlds and serves the customers well as well as the bottom line.  

It'll be interesting to see where you end up with the steam chamber/kiln.  

[Andries]

YH, when you mentioned that the steamed wood sold for the same price as the un-steamed, that didn't seem to make sense.
It's a value added process that you've paid for, but then you mentioned the "one stop shop" concept to maintain the valued customers. So, that probably justifies the small loss on the bf. $
As you move forward, is the drying cycle a rate limiter in your production? If you were to look at a vacuum kiln would that increase production, and do those kilns have a steam cycle as an option? 

[btulloh]

It's a value added process that you've paid for,

. . . or cost added / value subtracted depending on your point of view! :D

[boardmaker]

Robert,

We have a commercial built Steamer by AW Stiles out of McMinnville TN.  It will hold approx. 20,000 feet per charge.
I didn't have time to checkout Gene's info.  However, everything I have read so far seems accurate.

One thing I want to point out is how hard the steaming is on your equipment.   Anything made out of mild steel will be completely corroded/"eaten" in just several charges.  It's best if everything is made out of aluminum or stainless.  Also, the concrete doesn't hold up well either.  Not nearly as bad as the steel but it's still worth mentioning.  We've had decent luck with an expensive epoxy coating on the floor.  

We heat with a dual system of steam coils in a water vat in the floor.  Plus for a rapid heatup in the beginning stages, we inject raw steam into the water vat as well.  

If you have any questions, feel free to ask.  I'll help however I can.

[Ljohnsaw]

Very interesting read.  So steaming walnut is not really subjecting it to a direct blast of steam (that is what comes to my mind), but rather 'low temp' cooking at 200° and 100% RH, correct?  That's still pretty hot!  I've never done steam bending but I'm guessing that steam is pretty hot at 212° or better in the chamber?

[YellowHammer]

YH, when you mentioned that the steamed wood sold for the same price as the un-steamed, that didn't seem to make sense.
It's a value added process that you've paid for, but then you mentioned the "one stop shop" concept to maintain the valued customers. So, that probably justifies the small loss on the bf. $
As you move forward, is the drying cycle a rate limiter in your production? If you were to look at a vacuum kiln would that increase production, and do those kilns have a steam cycle as an option?

The steaming is part of the conventional kiln drying process, so isn't really a value added step, just part of the process of conventional kiln drying walanut.  Actually, it does two things that a DH kiln schedule doesn't, in that it purposefully runs the heartwood color into the sapwood, thereby allowing a higher yield per log.  It also, according to several kiln operators I've talked to, causes the wood to dry much flatter, with typically very little bow, which would be extreme in a board with a heavy mix of heartwood and sapwood.  I talked to one mega kiln owner and asked him if he would ever consider selling non steam cycle wanut and he replied no, the waste would be too high and run him out of business.  So there are two very valid commercial reason for steam drying walnut.
So in many ways, DH drying walnut, and heavy trimming of sapwood decreases yield.  Also, although I can use the DH kiln to manipulate and reduce the bow in walnut and cherry to some degree, I have no idea if the same steps can be used in a vac kiln.  Also, the yield of the less expensive vacuum kilns is not as much as I need.  With one of my Nyle kilns and air drying, I can produce maybe double the Idry output in the same time.

Boardmaker, I appreciate the info.  I did not know corrosion was at an excessive rate.  I know where McMinnville is, it's not too far away from me.  What species do you subjet to the steaming process? 

I have bought steamed walnut from a mill in McMinnville, and when talking to the owner, he said they built their first steam chamber out of concrete blocks and a big tarp for the door.  

[boardmaker]

Robert,

We only steam Walnut.  It does a very good job of mixing the heartwood and sapwood.  It's basically one solid piece of chocolate and very consistent from one board to another.

To switch to another species(like Cherry), I assume you would want to completely clean out the chamber and water vat.  It would be more time consuming than it sounds.  We've never done it.  We've never been asked for steamed cherry from our customers.

Just some quick math in my head, we probably steam 500,000 feet a year or so.  

Have you seen your current Walnut provider's steamer?  

[GeneWengert-WoodDoc]

The deterioration of a structure when steaming is well known. That is why a wooden structure is often better, as it is more durable, lower cost, and easily repaired.

When steaming is not done at 200 F plus or minus a few degrees and at 100% RH, the color is poorer and the sapwood color is not as dark as it can be.  Done properly, steaming will darken the sapwood.

[YellowHammer]

I have not seen the steamer from where I'm buying this wood, it is in Missouri.  I have however seen another steamer, but it was a nothing more than a big concrete bunker with a large door.  I didn't go in so I don't know exactly what they look like inside.

[nativewolf]

@GeneWengert-WoodDoc :

Well it is Thanksgiving.  I wanted to give special thanks to Gene for 

https://www.fpl.fs.fed.us/documnts/usda/ah528.pdf

His book, Drying Eastern Hardwood Lumber is a gem of a book and I found online as a pdf (link above) and to have him answer so many questions is really wonderful so thanks Gene!.  

Here's what lead me to this older thread:  we took several days off to help a poor and humble solo logger buck and sell a low quality WO and Walnut job.  He nearly doubled the pay of his highest truckload and my buyers were very good to him considering the small nature of the WO.  Fingers crossed  downpayment and he'll be a first time homeowner.  Anyway it was a 90 min drive each way and on the way home my son and I were wondering how in the world do these sawmills make money sawing walnut limbs at $1/bdft.  I mean if you slab off a 10" limb you have a juvenile core.  So while the kids sleeping in on Thanksgiving I started reading FF threads (thanks to @Jeff and all the others that keep it going) and came upon this thread and thanks to @YellowHammer I now have some idea of what's going on.  The steaming is reducing some of the twist and tension in the wood and enabling all the wood to be used so there is basically no juvenile wood.  As long as they can get to a 4-6" cant they are ok, they are going to steam it all and it will get sold.