Treating the inside of a bamboo "tube"

[Psilos]

Howdy all!

I've searched for an answer to my question here, but I haven't found anything, so I thought I'd join up and post it. :)

Here's what I know so far: I want to make a fairly long (2-3") bamboo container to hold water. I've read about heat treating the outside and that I should apply some sort of food-grade varnish to the inside. I'm unclear on exactly how to apply the varnish to the inside. Do I have to clean out the inside somehow? How? It will be a multi-section piece with all but the last node knocked out. Should I just pour some varnish in and swirl it around a bunch? I really appreciate any advice you knowledgable people might have!

Thanks, Richard

[Mark Meckes]

Hi Richard, you're right, we need to explore this subject more. The inside of bamboo is a whole different world!
Whatever I make with bamboo, the inner part of bamboo requires it's own special attention to preparation and finishing.
The inner wall of bamboo has characteristics and properties similar to the shell of a gourd.
The nodal diaphragm is of the same consistency, double-sided and thicker, containing only occasional cross-directional vein-like bundles of fiber.
I should note that different species have differing variations of this characteristic, which changes during it's growth. Inner wall characteristics vary with the drying/curing procedure.
Nonetheless, I presume all bamboo inner walls are `sheathed' with a layer of tissue-like velum, though for some species, it is barely visible, and others thicker. Sometimes, and with some species it detaches easily, other times it seems adhered with superglue...

Regarding waterproofing sealants, firstly, you mentioned food grade... is this a requirement?

Here's a thread called...
Question on preparing bamboo for water fountains (http://www.bamboocraft.net/forums/showthread.php?t=801)

Mark

[Psilos]

Mark,

Thanks for the reply! It would be good if the sealant is food-grade, but as long as it's non-toxic and liquid isn't kept inside the container for too long, I think it would be OK. Do I need to find a way to remove the velum from the inside before I seal it? (With a very long hone bit on a drill perhaps?) If I leave the inside as it is, will the bamboo come to harm over time? (Cracks, stains, etc.). I'm not going to be using a toxic species of bamboo (if they even exist), so I don't mind drinking a bit of bamboo water. Is there maybe a chemical wash I can use to remove the velum? So many questions!

Thanks again, Richard

[Mark Meckes]

Hi Richard,
The inside of bamboo is different with differing species.
Are you planning on working with locally fresh harvested, or imported materials?
Species, quality and condition of the material that you use will ultimately determine what you can achieve with your bamboo.

Re: moisture proofing, types of oils and finishes...
Though maybe in a somewhat different context to your intended application(?), this article provides valuable information and observations on types of finishes, and their moisture retententive properties.

Shaku Design; Oiling Bamboo by Nelson Zink (http://www.bamboocraft.net/forums/showthread.php?t=931)

Mark

[Psilos]

Mark-
I'll be using locally harvested bamboos. Not sure of the exact species, but it's a very common running species. I guess the big question is, do I have to do anything to the inside at all? If water is stored for a few hours, or maybe a day, inside the untreated tube, will there likely be any cracking or discoloration? I do intend to heat-treat the outside. Thanks yet again!

-Richard

[Mark Meckes]

Richard wrote...
> "I'll be using locally harvested bamboos. Not sure of the exact species, but it's a very common running species."

Okay, that's more then likely a Phyllostachys species, of which only a handful of species in this Genus that will get to 2-3" or larger in the NW USA, so we might be able to pin down the species name eventually, noting some which can be more prone to splitting.

> I guess the big question is, do I have to do anything to the inside at all?

I haven't quite figured out exactly what it is you're interested in making...

Most Phyllostachys only have a very thin layer of tissue, which can be either tenaciously hard to remove, though can sometimes upon drying, be taken out intact, or in sheets like the pic below...

>If water is stored for a few hours, or maybe a day, inside the untreated tube, will there likely be any cracking or discoloration?
I do intend to heat-treat the outside.

Now this sounds like a good backyard research project!

Cheers!
Mark