painting bamboo/ sandblasting bamboo

[Mark Mortimer]

Hi everyone,
I have been asked to make a quote for a bamboo fence, made from whole Tonkin canes, but they want the whole thing painted white. Not really my scene, I'm a bit of a purist, but, hey, it's work.
Has anyone successfully painted bamboo for exterior use? What kind of paint did you use? How long did it last? Has anone prepared the bamboo in any way, such as rough up the surface, or sanding it first?
I have to paint many hundred bamboo canes, so it I have to come up with a fast easy method. I am thinking of getting the bamboo sandblasted first. Has anyone ever sandblasted bamboo before?

[Mark Meckes]

Hi Mark,
I haven't painted any fencing, but it can look quite attractive. ( I have a pic of one which I'll dig up sometime).
Do to the waxy nature of the skin of bamboo, and that the underlying layer above the wood fiber is kinda similar to a shell, this makes it impervious to penetration of paints, stains and dyes.

However sanding will enable the paint to adhere to the bamboo.
Initial sanding isn't so much to make the smooth (it already is), but to cut through the waxy surface to give the paint something to grip onto.

Suggestion:

- Sand (perhaps with 80 or 120 grit sandpaper)
- Paint with a primer
- Sand with a lighter grade sandpaper
- If needed, apply primer again/sand
- Apply top coat of pigmented paint

More thoughts...

Oil/solvent based paints may meld better into the waxy surface but latex based paints have come a long way, are easier to work with/less toxic/easier cleanup. I would go with a high quality latex paint used for outdor patio/decks etc...

As with woodwork, multiple sucessive layers of a thin film of paint is the best prevention to chipping and flaking paint.
Using a paint sprayer will produce thin layers of paint though this can be achieved by brush, applied lightly.

My painting bamboo experience is mostly with smaller craft items.
The biggest concern is scuffs and nicks through their use, so sanding/multiple layers of paint, and a sealant is what I use.

A fence may or may not be subject to the same wear and tear as a bamboo toy, but nonethe less care needs to be taken after they are painted, (if the fence is painted prior to assembly) that they don't get scuffed during transport and construction.

Now, how to paint them? - horizontally, on sawhorses, leaning upright against something , or suspended in some way, or after a section is assembled or the fence is erected?

Mark

[Mark Meckes]

Hi Mark,
Here's a side thought that I posted into a thread as..
Has anyone used a tumbler to smooth bamboo pieces? (http://www.bamboocraft.net/forums/showthread.php?p=1935)

This bit concerns exploring ideas for removing the waxy coating...

"Curious too if anyone has made their own tumbler, ie from metal drums?

In theory, one could make a long tumbler, and fill it with bamboo poles and course sand or whatever, to remove the waxy surface skin, (cutin) off of the bamboo so that stain would absorb or paint could adhere better.
In practice, there's a few challanges involved to get a heavy tumbler rotating at the optimum speed, and not to be so noisey that it drives your neighbors insane!"

~ Mark

[Mark Mortimer]

I took a prototype panel down to the sandblaster and this is what I found:
It actually takes a lot of sandblasting: they guy thought it would just put a hole in it, but he, along with a lot of other people, underestimated the hardness of the culm surface.
Sandblasting provides an excellent key for accepting paint/stains/varishes etc. Unlike sanding, which takes off the impervious layer, but makes it smooth, sandblasting makes a pitted surface which is perfect.
I don't know whether it will be economically viable to do this as an option for fence panels. It is quite an industrial process, and takes the edge off the eco-friendly aspect of bamboo. Also, it really seems a shame to take off what is naturallly a great impervious layer, which has many advantages.
Anyhow, you will see the effect from the photos I'm uploading.
What do you think?

Photos from left to right:
1) Normal
http://www.bamboocraft.net/workshop/data/536/thumbs/normal.jpg See photo (http://www.bamboocraft.net/workshop/showphoto.php?photo=1420&cat=500&ppuser=31)
This shows some normal Tonkin cane (Arundinaria amabilis) which I'm using for this fence. It's imported from China.

2) Normal/stained
http://www.bamboocraft.net/workshop/data/536/thumbs/normalstained.jpg See photo (http://www.bamboocraft.net/workshop/showphoto.php?photo=1419&cat=500&ppuser=31)
This is a piece of normal Tonkin, with some stain applied. As you can see it's hopeless - the stain doesn't sink in, it just sits on the surface, and you can see the brush marks etc.

3) Sandblasted
http://www.bamboocraft.net/workshop/data/536/thumbs/blasted.jpg See photo (http://www.bamboocraft.net/workshop/showphoto.php?photo=1418&cat=500&ppuser=31)
This is a piece of sandblasted Tonkin. Evident is the pitted surface, providing a good key.

4) Sandblasted/stained
http://www.bamboocraft.net/workshop/data/536/thumbs/blastedstained.jpg See photo (http://www.bamboocraft.net/workshop/showphoto.php?photo=1417&cat=500&ppuser=31)
As you can see the stain has gone on evenly, and been absorbed by the culm. Good even coverage

5) Sandblasted/closeup
http://www.bamboocraft.net/workshop/data/536/thumbs/blastedclose.jpg See photo (http://www.bamboocraft.net/workshop/showphoto.php?photo=1416&cat=500&ppuser=31)
Finally a closeup of the pitted unstained surface of the culm.

[TribalWind]

WOW
actually, i really LIKE the 2nd photo, it looks like "tigerstripe bamboo"
does it still dry? i suppose itd just flake off,but maybe a clearcoat of something could seal it on? would make for an intersting flute or craft piece.!

[Mark Meckes]

Superb presentation Mark!
What type of sandblaster was used? Was it an enclosed box or open type?
Are there different grain particle sizes used with these sandblasters, for example to do coarse work, or graduating down to polishing?

Okay, I did a little web search and here's a link to sites and manufacturers of equipment....
"About Abrasive Blast Machines and Sandblasters" (http://process-equipment.globalspec.com/LearnMore/Manufacturing_Process_Equipment/Cleaning_Surface_Preparation/Abrasive_Blast_Machines_Sandblasters)

A separate thread has been started to discuss Sandblasting, health and safety issues. See SILICOSIS IN SANDBLASTERS: Health and Safety Issues (http://www.bamboocraft.net/forums/showthread.php?t=719)

Okay, here's a `natural' way to sandblast bamboo...
Ship the bamboo off to a sandy desert, stand your poles up in the dunes and let the prevailing winds do the job!
One might need to rotate the culms occasionally to get a uniform finish.
Only problem might be cracks in the boo and the boo tenderer from dry heat.