Comments on: Estimating Your Natural Hydraulic Lime Order

By: David

David — Tue, 29 Sep 2009 21:50:11 +0000

I’m interested in applying a tinted hydraulic lime skim coat to my interior walls.

The existing walls are standard drywall with a hawk & trowel finish done with drywall mud.They have also been painted with primer & latex paint.

I’ve been told that I can apply the hydraulic lime skim coat over paint but need to apply a product called Plaster Weld or M-Bond on the painted walls first.

Any recommendations on how to skim coat painted drywall?

How many coats of plaster?Do I need a traditional scratch coat? or just a base coat?

What kind of mix ratio of sand to lime?

Since this will be a thin skim coat I would assume NHL 2 with a fine silica sand would work?

By: Jerry McIntire

Jerry McIntire — Thu, 23 Jul 2009 20:06:56 +0000

Barnie, et al,
I am using hydrated lime and sand to make my plaster, as I learned from a member of the natural building guild in New Glarus, Wisconsin. Hydrated lime is a little more work in mixing but I’ve found it to perform well. I have made exterior stucco repairs and interior plasters (rough, scratch and finish coats) with hydrated lime.

Ratios: 1 lime : 3 sand for scratch and brown coats, 1:1 or 1:1.5 for finish coat.
Mixing: water first, then sand, then lime. Start with 1-2 liters water in a 5 gallon bucket, you can add more water after mixing a while if needed.

You will notice it gets drier after the first 5-10 minutes, that’s the time to get you moisture right for troweling purposes. Try troweling a small patch or a sample board to get the water content where you want it.

Mist with water at least twice a day after applying a coat of plaster. If outside, shade it from the sun. Wait 2-3 days between coats for carbonation, or longer if applying thick coats of one half inch or more.

Lime wash finish: I am making lime wash with the same hydrated lime. The first coat can be thicker, 1 lime : 1 water : .1 salt (that’s one tenth of a part salt).
Subsequent coats: 1 lime : 2 water : .1 salt
Mix well and leave for a day before using.
Wet the wall well the night before you will limewash. Do this for each coat.
Apply in the shade, mist it with water after 30-60 minutes, especially the thick limewash. Wait 1-3 days between coats, and at least 3 days after plastering before applying the first coat of limewash.

By: Andrew

Andrew — Mon, 27 Apr 2009 18:28:30 +0000

Barnie,
I am not as much of an expert in the science and art of plaster as some on this list. I cannot add anything more to the conversation at this point. I imagine there are those out there who have a much richer bank of knowledge when it comes to plaster. Seems like some are already engaged and I hope others will chime in as well.

By: BARNIE Says:

BARNIE Says: — Fri, 24 Apr 2009 13:58:53 +0000

Hi Jeff, Do you perhaps have a ratio of the mix for AHL-Pozzolan and Hydrated lime etc? I am out of luck so far.
Barnie.

By: BARNIE Says:

BARNIE Says: — Wed, 15 Apr 2009 15:21:22 +0000

Hi Andrew, Jeff,Gene and Charles,I think Jeff came up with something for a lot of folks who have the same problem. Unfortunatly I am still out luck so far but at least there is something to work on. Any coments from your side Andrew.

By: jeff

jeff — Wed, 08 Apr 2009 20:45:09 +0000

Gene,
I don’t know of any sites that talk about it. This is based on my experience with NHL and hydrated lime, mixing the two, mixing hydrated lime with cement and just knowing those who have talked about it. I have not done it but want to try it out. Just haven’t had the opportunity. Other pozzolans include ground up pumice, rice hull ash, etc. Do some research on pozzolans. Much of it depends on what you have available locally.

By: Gene

Gene — Tue, 07 Apr 2009 14:28:26 +0000

Jeff,
Interesting post. Can you recommend any websites that might go into a little more depth on AHL?
Thanks,
gene

By: jeff

jeff — Fri, 03 Apr 2009 17:13:54 +0000

You can make your own hydraulic lime or you can find it already made. It is called artificial hydraulic lime (AHL) and is frowned upon in placed like France and England where restoration work requires high quality control. One place to find AHL is at sugar beet plants. They use hydrated lime which is converted to a basic form of hydraulic lime during the sugar extraction process. You can also make AHL by adding some sort of pozzolan to hydrated lime, such as fly ash. It is highly recommended you experiment with these materials before applying them to your building.

By: Andrew

Andrew — Wed, 01 Apr 2009 13:52:40 +0000

Her’s another great site with a page about lime and the differences between the different types. This could be helpful for you Barnie.

http://www.naturalbuildingsite.net/lime.html

By: Andrew

Andrew — Mon, 30 Mar 2009 15:01:33 +0000

Hi Barnie. You cannot make your own NHL from other lime products, The cool attributes of NHL come from the way the product is manufactured. Check out the following website for information on the production process: http://www.transmineralusa.com/production_flash.html. I am sure that you can find someone to drop ship the product directly to you. I do not know if this will be cost effective though. Try contacting the folks at Transmineral USA (http://www.limes.us/contact.php)and see if they can help you. They import the product from France to the West coast of the US.