Help my friend make home-made rock sealant.

[RangerWickett]

My friend's cat recently died, and she wants to make a memorial marker to place in her garden. Her plan is to paint a stone, but she wants to seal the stone from the elements. Because she wants to make this a personal endeavor, she really wants to avoid using any commercial products. She's making her own paints, and wants to find a recipe for home-made sealant.

So far she's found recipes for wood sealant involving cottage cheese and lime, but she's not sure that'll work on stone. I was hoping someone here is crafty enough to know how to make rock sealant from scratch.

 

[Pbartender]

It depends on what she means by "home-made" and "sealant". Basic sealants (shellac, for example) are simply a resin that's been dissolved into a solvent like acetone or alcohols... You brush it on, the solvent evaporates and leaves behind the sealant coating.

Here is an article I found for making a marble sealant out of Tung oil...

A marble sealer is usually made of highly toxic solvents that can be degrading to the health. However, you can make your own marble sealer by a simple mixture of drying oils and mild solvents. While linseed oil is a good drying oil to use, it does cause discoloration on marble so the best oil to use is Tung oil. Tung oil is derived from the nuts of the Tung tree—a tree common in China. When applied on a wooden or stone surface, it dries out completely to leave an effective barrier against water and other contaminants. To act as a marble sealer, however, it has to be mixed with a mild solvent. Read on for more information.

Tools and Materials

• Pure Tung Oil
• Citrus Solvent
• Stirrer
• Plastic Container
• Spray Bottle, Brush or Cloth
• Rubber Gloves

Step 1 – Preparation

To make a sealer out of Tung oil, prepare equal amounts of citrus solvent and Tung oil. The solvent is an important ingredient in the marble sealer because it allows the oil to be evenly spread on the surface of the marble and to dry out completely. Citrus solvent is also a natural and safe solvent that can replace naphtha and mineral spirits that are commonly used to prepare sealers. To prepare the mixture, pour one part of citrus solvent and one part of Tung oil in a plastic container. Never use a metal container because metal may react negatively to the mix.

Step 2 – Cleaning the Marble

In order to produce a great finish, the marble should be free from dust, debris, stains and discoloration. Never use vinegar to clean the marble because it is too acidic and may cause more damage than good. Use baking soda paste instead along with hydrogen peroxide if necessary. Or, make use of a damp cloth to clean the surface. If it does not have any stain whatsoever, use a clean cloth to wipe away the dust and debris on the surface.

Step 3 – Applying Tung Oil Sealer

When using a cloth to apply the sealer, make sure to use rubber gloves to protect the hands. Soak the cloth in the mixture and use it to spread a thin coating onto the marble. Make sure that the thickness is consistent. If not, place the sealer in plastic spray bottle and spray in on the marble. Another way to apply the sealer is to paint it thinly using a brush. Since the Tung oil easily dries off unlike other drying oils, a coating is okay. Allow the first coat to dry before applying the next coat.

Step 4 – Applying the Finishing Coat

Apply another thin coat if proffered and allow it to dry before applying the finishing coat. The finishing coat should be applied thickly to ensure that the sealing effect lasts longer. Unlike other drying oils, Tung oil dries completely and a lot faster so it is okay to apply a thick coat for the last coating. Allow the sealer to dry
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Also, "boiled" linseed oil (look it up, it's not exactly what it sounds like) can be mixed with kerosene or paint thinner to make a home-made concrete sealer.

Also, also, plain old mineral oil is often used as an inexpensive (but more frequently reapplied) sealant for stone, especially soapstone counters and outdoor flagstone. Apply it liberally, leave it sit for 10 minutes or so, and then wipe off the excess.

Also, also, also, I'd recommend doing just a little experimentation with the paints and potential sealants before making the final memorial... Some of the oils and solvents used for the sealants might not play well with paint, if the paint is applied first.

 

[Umbran]

It depends on what she means by "home-made" and "sealant".

What it sounds like she wants is not so much a sealant, as a clear protective top-coat or glaze, which is not the same thing.

"Sealant" typically refers to a substance penetrates the surface of a material, and takes up residence, to keep other substances from getting in. Your mineral oil on slightly porous stone or wood is a good example - you fill all the microscopic pores in the surface with oil, and the oil won't admit water.

If you're painting the stone, a sealant isn't necessarily going to help keep the paint on the stone, it'll keep other things from getting into the stone - and may itself be kept out by the paint underneath, depending on the paint.

I'd suggest you go talk to a local ceramics expert, as many of the techniques used to decorate ceramics will also work on stone.

 

[Pbartender]

I'd suggest you go talk to a local ceramics expert, as many of the techniques used to decorate ceramics will also work on stone.

That's a good idea... Glaze it, instead of painting and varnishing it.

And glazes are not especially difficult to make yourself.

 

[Janx]

That's a good idea... Glaze it, instead of painting and varnishing it.

And glazes are not especially difficult to make yourself.

Well, make sure you've taken a pottery class and know how to mix glazes. The powders are metallic and can be quite dangerous to inhale.

You're also going to want to use the school's kiln. Those things aren't cheap.


My wife spent several years making pottery.