Don MacRostie and his Torrefying Oven

The Luthier Bench Knowledge Base

Don MacRostie is the master of many things. In addition to being a fine mandolin builder, Don has continued to embrace new technologies that allow him to make better instruments. Dan Erlewine went down to Don's farm to help us get the most out of our interview with him. The whole thing's on Patreon, if you want to see everything, but here's a clip that I thought you'd want to see. Don's gone a step further than any other home-shop builder I know. He's put together a torrefying oven to age his wood in order to give it the best possible tone.  To watch the whole interview (and tons more!), join us on Patreon at www.Patreon.com/IanHatesGuitars.

Transcript

00:00Yeah, so should we go up are we done in this room or should we go look at the

00:18This is oh, what are we doing here?

00:23Are made of torrified wood, okay

00:27and

00:29When I started doing it I

00:31Sent it out to commercial torrifiers, and I had them do it at the lowest temperature

00:36They would do it at and I think was about a hundred and eighty five

00:40Centigrade and I thought it was too much

00:59I

01:03Think this is out of the same tree

01:08But

01:10This one the one in my left hand

01:13Was 185 and this is 170. Uh-huh, and you can see the color difference. It's quite different

01:21Yeah, and and you can over

01:25Guess it gets brittle

01:27Early experimentations I was doing this I

01:31Wasn't getting it even I

01:33Was getting more hit down here less down here. You know, it was you see how I need uneven the color is. Yeah

01:42So I've done a lot on this

01:48To put in a circulating fan

01:52And

01:54I've got a

01:55Thermometer that goes into my vessel this the wood is inside of here. It's not open to the

02:03elements and

02:06Torrifying you have to keep the oxygen away. That's the main point. There are several ways of doing that

02:13And I do it by pushing nitrogen

02:15Through this container. Okay, I trickle

02:20Nitrogen into that when it's at the height and the upper temperatures

02:24Okay, and so it pushes anything out which would be you know, any oxygen would be pushed out

02:32So getting nitrogen into that box has got to be a little bit of an engineering feat without melting whatever it is

02:38It's delivering it

02:50Uh

02:51Let's see if that light will come on. Could you still make some cookies in there if you needed to? Oh, yeah

02:56I make pies in here Thanksgiving. Okay good. Uh, I

03:01Do do you really?

03:05Do they taste a little sprucey

03:08I'll tell you what

03:10Maple when you heat it has this

03:13smell and

03:15Maple syrup. Oh good. This has a really nice smell and I do a lot of maple

03:21So it's maybe it's a maple leaf

03:23But anyway, this is this goes into a hole in the side of the box and it's got a tapeless layer on it

03:29So I push it all the way in and I'll I'll put steam

03:33There's a part of the process that takes steam in the can in the box and part of the takes nitrogen

03:40So I'll push from the outside. I'll push into that container from here

03:45Here's the thermometer that goes into the container

03:49So I know the inside temperature and here's a thermometer in the oven. I've got two thermometers up here

03:54I know the the temperature inside the box and in the oven

03:58So and it just hold it just holds drilled in there with a piece of

04:03copper

04:05So

04:07Are the commercial tour fires are they using vacuum or are they using nitrogen as well?

04:13Well, I would think that in those huge ovens it might be more efficient to use vacuum or

04:20I've also heard of them being completely sealed and a flame burns the oxygen out

04:27Okay, I've heard of some tour fires that will burn the oxygen out and then it's sealed enough that nothing gets in

04:37I've also heard of

04:40torrifying

04:42Containers exploding. Yeah, this isn't that none of this is sealed that tight again. Yeah

04:49Yeah, but but with a small box I have

04:53I don't think I have four or five dollars in each load in there in nitrogen cost

05:02You've got a lot of wood put up like if you if you had your choice

05:06Do you is there anything to have in like 15 year old wood versus

05:11Torrified or do you think it's roughly kind of equivalent at this point? Do you think torrification is good enough to?

05:19outpace

05:20naturally aged wood

05:23I

05:24Should say

05:25Torrified. I mean, I don't I

05:29Don't think

05:36So

05:42Here here's the same wood you can see the same knot on either side

05:46This side I'm using my iPhone light this side. Let's turn that overhead light out

05:52It might show up better right right behind that dust collector there that dust pipe. You got it right there

05:58Okay, so this side

06:00Is not torrified

06:02They're both the same thickness

06:07Interesting and that's what I was told

06:14Dana Bourgeois was telling me about this

06:20And that if you put a light inside of a 30s Martin you won't get any pass-through I

06:30Don't know if you've ever tried that you did that at the end shop first ones did I yeah, okay

06:36yeah, so he told me that and

06:38So basically what this is doing is mimicking the older would and why my theory?

06:45I don't I can't prove anything, but my theory is that

06:50The stuff that's in there besides the water the oils the resins

06:56the sugars are in there and a fresh-cut piece of wood is

07:02Liquid

07:04Liquid and when you torrify

07:07you turn it into a dry and

07:10The sap in wood when it dries. It's kind of granular like rosin

07:17So instead of the light being

07:21Transmitted through when the light hits it. It's randomly diffused refracted

07:27Refracted refracted. Yeah, whatever the term would be it's yes, so it very little of it passes straight through

07:34And those resins cure

07:37Over time or if you do something like this

07:42That's really cool, that's I I and I think you're the first person I've ever heard of doing

07:51Doing home home bake

07:54Yeah, like I've never I've never heard of anybody else doing it

07:58Is it is it expensive like getting a nitrogen tank set up to do it is it is it well

08:04I think I I think I mentioned that I think I have four dollars in each each box of

08:09Torrified okay, I my bottles. Here's a nitrogen bottle

08:15the refill on them is

08:19$26

08:22So that you can just get that at a welding supply like yeah, that's what you would use for like doing TIG welding or something

08:29So what kind of difference does it make?

08:32When you torrify a pie or a turkey rather than the bacon

08:38Flavor

08:51You

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