[Strawbale] Strawbale Digest, Vol 7, Issue 24

[Michel Couvreux]

Jacek,

As you know, by the European Standard, Natural Hydraulic Limes are 
classified in 3 different categories: NHL 2, NHL 3.5 and NHL 5, going from 
the weakest (NHL 2) to the strongest (NHL 5).
The reworking time will vary with the type of NHL used: 24 hours for NHL 2, 
12 hours for NHL 3.5 and 8 hours for NHL 5. These numbers may vary widely, 
depending on the conditions in which the mixes are kept, the mixing ratios, 
etc. For exemple, 18 hours for the NHL 3.5 is pretty common.
As a general rule, if more than 1/6 of the water used initially to mix the 
mortars is necessary to bring the mortars back to a workable state, the mix 
should be discarded.
When the mortar is left several hours before being reworked, it should be 
covered with, for exemple, some plastic or visqueen in order to keep its 
water content and limit the contact with the air.

Michel

Michel Couvreux
TransMineral USA, Inc.
501 Lakeville Street, Suite F (Physical)
201 Purrington Road (Mailing)
Petaluma, CA  94952
707-769-0661
707-769-0352 Fax
transmin at sonic.net
www.limes.us
----- Original Message ----- 
From: <strawbale-request at listserv.repp.org>
To: <strawbale at listserv.repp.org>
Sent: Wednesday, January 31, 2007 10:00 AM
Subject: Strawbale Digest, Vol 7, Issue 24


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> Today's Topics:
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>   1. Re: Strawbale Digest, Vol 7, Issue 18 (Michel Couvreux)
>   2. Hydraulic vs Hydrated Lime plaster (Jacek Zagorski)

>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 30 Jan 2007 10:58:11 -0800
> From: "Michel Couvreux" <transmin at sonic.net>
> Subject: Re: [Strawbale] Strawbale Digest, Vol 7, Issue 18
> To: <strawbale at listserv.repp.org>
> Message-ID: <003201c744a0$976df390$5f64a8c0 at micheldell>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> I would like to make some comments on Derek's statements.
> Hydraulic lime does not set in a short time. It is a product that can be
> reworked up to 24 hours.
> To say that it will harden in the mixer, bucket or trowel is wrong.
> For exemple, you may mix a batch and use it several hours later. Yes, it
> will harden, but you mix it again and it comes back "alive". As a matter 
> of
> facts, it will result in a mortar which is easier to spread. In the old
> time, they used to mix the mortar in the evening, let it sit covered
> overnight, and remix it the next morning.
> As for the inexperienced plasterer, working with Hydrated Lime requires
> skills and time, and the result is far from being guaranteed. Too many
> factors like slow curing, thicknesses, ratios, etc. will give huge
> variations on the performances. I do not know of any reliable technical 
> data
> for plasters with Hydrated Lime.
> On the contrary, the use of Hydraulic lime does not require special 
> skills.
> Any ordinary stucco contractor can use this product by following a few 
> basic
> guidelines. The performances are known and the technical data is 
> available:
> you know what you get.
> One more comment on the Hydrated Lime: by reading Derek's comments, one 
> may
> believe that you can start plastering a wall and continue months later 
> with
> the same mix. This is wrong: you would create a cold joint and more
> cracking. To be able to keep a mix for months in a bucket is irrelevant
> (except perhaps for interior finishes where you do not need a lot of
> material) simply because plastering generally requires a lot of material
> (several cubic yards).
>
> Michel
>
> Michel Couvreux
> TransMineral USA, Inc.
> 501 Lakeville Street, Suite F (Physical)
> 201 Purrington Road (Mailing)
> Petaluma, CA  94952
> 707-769-0661
> 707-769-0352 Fax
> www.limes.us

> Message: 2
> Date: Tue, 30 Jan 2007 15:35:34 -0800
> From: Jacek Zagorski <jaz at shastanetworks.com>
> Subject: [Strawbale] Hydraulic vs Hydrated Lime plaster
> To: strawbale at listserv.repp.org
> Cc: Michel Couvreux <transmin at sonic.net>
> Message-ID: <32396FB5-F2A1-48DD-88FB-9583B247CD74 at shastanetworks.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Michel,
>
> We spoke a couple months ago regarding our strawbale/earthen/lime
> plaster home near Ashland, Oregon.
> We have not plastered yet but will be doing so shortly - hopefully...
> it's warming up and we found a nice vein of clay. We'll wait to seal
> up with NHL when it's much warmer.
>
> The hydraulic lime you're talking about below is the Austier NHL? And
> this is true for the 2, 3.5 and 5 ?
> Should it be covered with water while sitting overnight or just
> covered in the mortar mixer or some other tubs?
>
> Thank you for your advice.
> Jacek Zagorski
> cell # 541.941.3252