Sticky Earthen Floor

Greetings,
I'm prepping for the install of an Earthen Floor in my building. I have been planning on installing the tubing as well to heat the floor for hydronic radiant heating. I've received a couple unsettling accounts around the negative impact of hydronic heating systems in Earthen floors, including the following:

A local Natural Home builder experienced with Earthen Floor installation was sharing some insights about hydronic heated systems in earth floors and how they effect the oil finish.

He mentioned that when the earth heats up, the placidity factor of earth increases because of the linseed oil. He shared that the oil becomes tacky when heated to the point where he no longer turns on the floor heat because the floor surface gets too sticky and ruined his rugs.

I had not heard of this happening before, but seems worth investigating. I'm not sure if there is an additive that can be used in the linseed oil that helps it stay stable when heated? Might the addition of Portland cement, or lime into the Earthen Floor help with its properties when heated?

BTW, for my install I'm following the procedures and protocols for a, "compacted gravel (road base) subfloor", as outlined on pp. 109-112 in the book: "Earthen Floors - A Modern Approach to an Ancient Practice" by Sukita Reay Crimmel
And James Thomson Copyright 2014 by New Society Publishers. Though the system of the install is really tangential to the issue of how hydronic heating affects the finish surface of these types of floors.

Many thanks!
Bill

i personally don't favor the idea of putting the warm water tubes throughout the floor. not to be critical, or suggest you should not, but i generally don't favor any idea that feels over complicated, too much to go wrong. it just does not strike me as a good idea to put any kind of water, in tubes, or even complicated pipes and such like in conventional houses, inside a floor.

with that said, in reponse to what your main question seems to be - you can use many different types of sealers, such as things you can purchase at your building supplies store. i have seen earthen floors finished off with polyurethane and other types of acrylic sealers. ...and because thats just what the person had lying around leftover from other projects.
i do think its a shame, and linseed oil, and or beeswax are the best way to go.

but if that appeals to you, you can use a variety of different commercially available sealers, which will form a much harder and protective surface for the floor.

We used a resin based hardwood floor finish over the (cured) linseed oil sealed floor.  It works well - no stickiness.  I don't know if it would have been sticky - we were going to use the hardwood floor finish regardless.

Our hydronic tubes are about 3 inches below the floor surface spaced 9 inches apart and are heated by a solar thermal system.  Even though the house is only about 800 square feet, there are three zones (& thermostats).  The bathroom/foyer (north side) are set the warmest, kitchen/living room less so, the bedroom zone we rarely heat.  We really like how it works.  It takes about 3-4 cloudy/cold days in a row before we have to build a fire in the woodstove.

I don't have experience with using radiant floor heating with earthen floors, but my own earthen floors have had issues around my rocket mass heater. The heater gives off enough heat to warm the floor wherever the cob attaches and the floor dries out. I think as the oil heats up it continues to penetrate into the earthen floor, but it has led to re-oiling this section a number of times.

It might be worth experimenting with various additives and also various other fats with higher melting points. I know that they used to add blood to the earth floors to seal them and i also know that linseed oil can be fairly fickle when it comes to setting/ being absorbed and adsorbed.

Lime might do some weird things with linseed ie mixing an alkali and an oil normally makes soap - not an ideal floor material. It might also depends on the mineralogy of the clay ie a high activity strength clay (ie volcanic) should form a stronger bond than a low activity clay, or a clay from an area high in calcium is going to give a low rate of adsorption.

I suspect that another problem might be getting the sand/clay ratio right to avoid cracking when the clay dries.

If all else fails then a watery mix of pva glue works wonders on dusty things.