[Cob] Bad news: Countertop will need to be rebuilt!!

[Ocean Liff-Anderson]

Ok, I've been reading about this sticky wet countertop for weeks now,  
and have to chime in.

(Disclaimer:  I've made the following comment on this list several  
times before, but here it again bears repeating...)

This project is a good reason to learn earth building from "experts"  
who have experience in proper techniques.  Kiko Denzer and Ianto  
Evans always recommend making "test bricks" of cob or "test swatches"  
of plaster and floors, letting these dry completely to check for  
cracking/hardness (usually insufficient sand).  Also you need to test  
any finish treatment you are going to use on these test swatches,  
BEFORE applying it to your beautiful creation.  Hence the trouble you  
are having with red food coloring, veggie oil, etc...
_____

So on to solving your problem:

Sounds like your counter is either saturated with veggie oil, which  
will never dry, or was treated while still wet with water?  Think of  
trying to paint wet wood - would you expect the paint to adhere or  
dry, ever?

Cob floors are treated with several coats of "boiled linseed oil"  
blended with various amounts of solvent - it's nice to use citrus  
solvent instead of turpentine (huge areas lead to very stinky and  
toxic air).  For example, there's a little cob building at  
Breitenbush Hot Springs which has a floor which was obviously treated  
with turpentine - you go in there and the toxic fumes are still  
strong, YEARS later!

For application to a floor (not unlike a countertop situation), one  
must start with a bone-dry earth/sand floor surface, apply the  
linseed/solvent mix, let dry completely, then apply another coat,  
dry, then another coat, etc.  The final layer is a mix of beeswax  
with boiled linseed - caution here, since too much beeswax results in  
a sticky surface that never dries, stays tacky...(ask me how I know  
about this!)

I know everyone on the coblist wants natural products, but raw/ 
natural linseed oil will NEVER dry.  The "boiled" variety actually  
has "drying agents" - which are a bit nasty (carcinogens, etc).  You  
might find a natural version with citrus drying agents, let us know  
if you do.

However, all the above directions won't help with your existing  
sticky wet countertop.  If your surface has a deep penetration of  
veggie oil, it will likely stay soft, tacky, and red-staining  
FOREVER.  I don't agree that a surface treatment of some conventional  
wood sealant would help - again, imaging trying to paint wet wood.

Sadly, I think you'll have to start over - chip off the red clay oil  
mix, build again with a proper cob floor mix, let dry, then apply the  
above linseed treatment.  Sorry to be the bringer of bad news, but I  
don't see any way out of this, especially if this is to be a high  
impact commercial surface!  And when you do rebuild it, please call  
Kiko Denzer for advice, an expert on cob surface treatments,  
plasters, etc (I have his phone number, ask me for it), and make test  
patches and test your surface treatments before applying them!

Good luck!
Ocean Liff-Anderson

Ahimsa Sanctuary, Philomath, Oregon
www.peacemaking.org

FireWorks Restaurant, Corvallis, Oregon
www.woodfiredeatery.com


On May 15, 2008, at 11:24 AM, Stephen Karrington wrote:

>
>> The polishing is a good idea... use a smooth stone, or cut a piece
>> of plastic out of a container and start rubbing.  You'll catch on
>> pretty quickly to how to do it... too much pressure moves the
>> material, too little and you don't get a polish.  It's a lot of
>> elbow grease.  I've wondered at using a grinder with a speed control
>> (go slow!) and a soft wheel on it.
>
> I was thinking about one of those car buffing machines. That might do
> the trick.
>
>> You're in a tough spot if ALL the material has veg oil through it.
>> It likely will never dry completely.
>
> That's the problem! Its been months already.
>
>> You might be able to impregnate it with a drying oil like boiled
>> linseed mixed with turpentine.  But beware, most 'boiled' linseed
>> oil just has lead, mercury and other heavy metal drying agents in
>> it... but it works.
>
> I have the natural linseed oil. What % of linseed oil to turpentine
> should I use? Can I use 100% turpentine and hope it dries it up?
>
>> Usually by a week it's quite dry and hard.  You
>> can buy organic boiled linseed oil that doesn't have junk in it...  
>> but it's horribly expensive.
>
> I have plenty of containers of natural linseed oil. I don't think its
> boiled. Looks raw to me. Smells good too. I could try a combination  
> of linseed and
> turpentine and hope for the best.
>
>> Those are my only thoughts at this time.  I wish I had better  
>> news, it's a beautiful counter.
> It looks real good. If only it was usable :) I was thinking about
> putting some ceramic tiles in the worker area of the counter top to
> cover it. Someone suggested before using a blow dryer or I think blow
> torch to it. But the torch might burn it and turn it black.
>
> Thanks.
>
> S
>
>> Rodger
>
>
>
> _______________________________________________
> Coblist mailing list
> Coblist at deatech.com
> http://www.deatech.com/mailman/listinfo/coblist