Thread: Sealing natural stones

Just wondering, not looking to do this, unless its warranted.
Why do folk seal the sides and bottom of natural stones?
What is the reason?
Just trying to understand more on this subject.
Thanks.

Can't speak about all naturals but at least as far as Jnats are concerned they are sedimentary rocks. In sedimentary rocks there is concern that water could cause swelling and eventually result in cracking along the layers. Some people have seen it happen, others have not. I seal mine just for the peace of mind.
By sealing them you strengthen them and prevent water from getting in from the sides and thus decreasing the risk of cracking. At least that's the theory
Here is an jnat that cracked.

I see. Well then maybe i will seal my Jnat.
Anyone else have anything to say on this?

I've heard the same.

Yes, most jnat hones are layered and sealing keeps water out of the layer cracks or other cracks.

Two lacquers are traditionally used. On is the sap of the kiurushi tree, filtered and colored. It's basically poison sumac sap and will do the same thing to you if you get the uncured lacquer on your skin. It polymerizes with moisture in the air and frequently a humidifying cabinet is used to cure it. It's very strong when coupled with cloth or paper and can be used as a glue to mend things. It's kind of a natural fiberglass. It loses it's sensitizing property when it's fully cured.

The other traditional lacquer which is not a sensitizer is cashew lacquer, and it's available here in the States though it isn't cheap, about $40 for a 100ml can. It looks and feels like kiurushi and is available in several colors. It dries to a very high gloss. If the stone that you're coating has a layer crack, you can use mulberry paper with the lacquer to reinforce it. The tomonagura below has been reinforced that way and you can see the overlap of the paper if you look closely.

The stone on the stand has been coated with the transparent amber #51, and the stand with the red transparent #53, and the foreground stone with black #91.

Marine spar varnish is a good and cheaper alternative.

Cheers, Steve

I sealed mine with clear nail polish no complaints. Although if I could go back I might not have sealed it since I like how the stone felt. My other jnat is sealed with something called liquid glass I believe, it came sealed so all I can do is show you how it looks.

Image of bottom of stone with liquid glass.