How to Thin Linseed Oil

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What You'll Need
Cardboard or newspaper
Heavy-duty rubber gloves
Safety glasses
Glass measuring cup
Linseed oil (boiled)
Mineral spirits (such as turpentine)
Quality floor varnish
Wooden stirring utensil (a paint stirring stick or three is perfect)
Metal containers or buckets

Using linseed oil to cure wood surfaces has been a popular practice for hundreds of years. Linseed oil is a natural preservative and is very effective in curing the wood to withstand both the elements as well as the wear and tear that, as in the case of a wood floor, it receives. Linseed oil will absorb into the grain, even on a molecular level with wood, preserving it and giving its surface high durability.

The primary trouble in using linseed oil is that raw linseed oil takes a long time to cure, up to two weeks in a dry, well-ventilated area and, ultimately, a couple of months if it is applied to surfaces that are exposed to extreme heat, cold, or high humidity. The bottom line is that pure linseed oil can be very difficult to work with, particularly in a case where it is a wood floor or deck that is being finished with the substance. Here you will find some tips on thinning linseed oil so that it retains its preserving qualities while being modified into a substance that is easy to work with and will actually dry in a span of time that makes it realistic to use.


All of the materials used in this task are flammable. There are numerous stories of linseed oil spontaneously combusting, so make sure that you are working in a well-ventilated area and that you know how to dispose of any stirring utensils or rags that become saturated with any of the solutions you’re using. You may want to put cardboard or several layers of newspaper down on the work surface to protect from splashes or spills. You will also need to don safety goggles, gloves, and coveralls to protect your eyes and skin from any contact with solvents or materials.

Mix Ingredients

Using a glass measuring cup, one that you will not want to use again, measure out equal parts of the linseed oil, spirits, and varnish into the metal bucket or container. Use a wooden utensil or paint stirring stick to mix the solution together. You can then apply this solution in thin coats to your floor, decking, or another wood surface, using a brush to spread it evenly.

Storing the Finish

Any unused portion of the mixture will need to be stored in a heavy-duty metal can or container that should be tightly lidded. Any rags or applicators that have been used should be stored in a metal bucket filled with water until the proper disposal method can be done. Check with your local ordinances for instructions on how to get rid of such items in the safest and most environmentally friendly manner. Store all materials and used applicators away from heat and flame, as they will be incredibly flammable.