Penetrol vs Boiled Linseed Oil – What Will Work Better?

Many metal and wood treatment oils are on the market, each with one or more characteristics that set them apart. Two of these are Penetrol and Boiled linseed oil.

Although they are both great for treating surfaces, many DIYers and homeowners often wonder what will work best between Penetrol and Boiled linseed oil.

This article discusses that concern and more. Read on to find out more.

Penetrol Vs Boiled Linseed Oil

Penetrol is a product of linseed oil mixed with a few other ingredients. Penetrol is essentially a product of linseed oil, long oil alkyd resin, and Stoddard solvent.

It is an oil-based additive of high quality that is colorless, low-odor, and non-toxic while curing. Penetrol can be used on metal and steel. It can also be used on wooden surfaces to improve adhesion and ease the use of paint brushes when applying the paint.

This blend of natural oils has been used for over five decades globally because of its long-lasting quality, and ability to reach tiny spaces. And the fact that it dries up without evaporating makes it a great choice for treating bare metal and wood.

There are products specifically made for the choice of workpiece you want to work on.

On the other hand, Boiled linseed oil is a versatile treatment oil derived from regular linseed oil, which is derived from flaxseed. Raw linseed oil, otherwise known as flaxseed oil, takes longer to dry up after use.

So, to reduce this drying time, Boiled linseed oil was produced. After linseed oil goes through a heat process and gets mixed with drying agents, the resulting product becomes thicker and dries up faster than its raw form.

Contrary to the misconception that regular linseed oil is boiled to make boiled linseed oil, boiled linseed oil is raw linseed oil that is treated with hot air and mixed with lead acetate and cobalt-manganese. This removes the oxygen in the raw oil and other impurities.

This is why many manufacturers call it “purified linseed oil”.

Boiled linseed oil is used for many projects. It is so versatile that it can be used for wood, metal, and many other projects.

What Will Work Better?

There is no straightforward answer to the question. However, you can be better equipped to know which one to choose for your project after understanding how they work.

Penetrol stops rust by penetrating the rust to rid the metal surface of oxygen and moisture. At a close inspection, you will find that rust is no more than a sponge of air on the metal surface.

This “sponge of air” contains oxygen and hydrogen, forming iron-hydroxide, which is another name for rust.

Since Penetrol has a very low surface tension, it penetrates the sponge closely to eliminate the air and moisture. This leads to the complete saturation of the rust all the way to the bare metal surface. It essentially removes the “food” that rust thrives on and changes the existing rust into a protective coat.

Also, unlike boiled linseed oil which is used for much larger surfaces and to build a moisture-repellent surface, Penetrol is more of a patina.

Perhaps the main reason Penetrol is used is its ease of use. Unlike Boiled linseed oil which you may have to bake in an oven or with a blowtorch for best results, using Penetrol only requires applying it on the surface and cleaning the excess.

Boiled linseed oil, on the other hand, does a whole lot more than Penetrol. For wood, Boiled linseed oil penetrates. It penetrates the fibers of the wood to strengthen it as a whole mass.

It penetrates deep into the wood to saturate it.

This helps protect the wood from changes in humidity. And for metal works, baking the metal after applying the boiled linseed oil not only makes the workpiece durable but also gives the metal workpiece a golden-brown color.

Boiled linseed oil is a great option for rust inhibition on metal surfaces. In terms of drying time, Penetrol dries faster than Boiled linseed oil. Penetrol fully cures within 12-24 hours, while Boiled linseed oil must be left for no less than 24-48 hours to cure fully.

And finally, unlike Penetrol, applying and baking boiled linseed oil on metal will give you a really nice amber color and a very tough coating. In many instances, the coating is even tougher than good-quality paint.

Although you can scratch to dig into it, the boiled linseed oil coating is so tough that it is almost scratch-resistant when done right.

What Can Make Them Work Better?

Whichever products you use, here are some tips to make your project perfect when you use Penetrol and Boiled linseed oil.

How To Get the Best Results with Penetrol?

If you are prepping bare metal, you want to do the following:

  • Before anything, you want to remove all loose rust, debris, dirt, oil, or any grease from the surfaces to be worked on. You can do this by washing, wiping down, or dusting, depending on the nature of the dirt.
  • After ridding the workpiece of contaminants, you want to leave the surface to dry from the cleaning. This is important for the next step, which is the saturation of the metal. Use a towel to apply the penetrol product over the dry surface of the metal.
  • After applying the penetrol, it is important to wait for at least 12 hours. If you like a dim glossy sheen, you can return with a dry rag to wipe the surface of the metal. You do not need to soak the towel or rag in anything.
  • If you are working on a brass, chrome, aluminum, or copper surface, it would be best to scrub the surface with some steel wool. You want to first soak the steel wool in penetrol before scrubbing with it. Afterward, you want to buff the surface with a clean rag.
  • If you want to condition your fiberglass with penetrol, it would be best first to clean the fiberglass thoroughly. You want to ensure that the surface is free of dirt, dust, or debris. After cleaning the fiberglass, you need to wet a rag with some penetrol and wipe the fiberglass down. Finally, you want to buff the fiberglass surface with a clean, soft cloth after 5 minutes.
  • If you wish to use it for faux finishing, you can increase the working time and the brushability of your paint by mixing the penetrol with your oil-based paint. However, if you are working on a vertical surface; you want to add only very little penetrol because too much of it can cause your paint to sag.
  • Ensure that you mix the right proportions. You can use a disposable cup for measurement. A rule of thumb when using penetrol for faux finishing is to mix 3 cups of the alkyd (i.e. the oil paint) with a cup of penetrol.

How To Get the Best with Boiled Linseed Oil?

Boiled linseed oil is more versatile than penetrol and is, in fact, one of the main ingredients of penetrol. To get the best out of your boiled linseed oil, here are a few tips to make it work better:

  • Adequate prepping

The steps to prepping wood will differ from prepping metal, but both are very important if you want an excellent protective, and beautiful finish.

If you are working on metal, it would be best to sandblast the metal after cleaning it to have a completely bare surface. The goal of prepping the metal surface is to get rid of the rust and dirt of the metal.

If you are working on wood, it would be best to sand it. The goal is to get rid of the dust, dirt, grime, and other contaminants that may come between the oil and the surface of the wood.

  • Baking or Blowtorching the Boiled Linseed Oil on the Metal Project

You cannot do this for woodwork. You can polish the wood surface with a clean cloth to improve its appearance after it has fully cured.

You can improve the durability of the protective coating by baking the boiled linseed oil on the metal.

There are two simple ways to do this: baking the boiled linseed oil on the metal or blowtorching the boiled linseed oil on the metal. The choice usually depends on how big the metal work is.

Baking will be appropriate for small metal pieces like metal clamps, dumbbells, small metal tools, and other small-sized pieces that can fit into an oven.

Blowtorching, however, will be more appropriate for metal works that cannot fit into an oven, like a big metal sculpture or a metal truck bed.

If baking, you want to coat the clean metal workpiece with your Boiled linseed oil. Let it dry for a minute. Leave it in the oven at 400°f for an hour. It should come out with a strong amber and almost scratch-proof coating.

If you want a darker color or to double the coat, all you have to do is recoat with more boiled linseed oil and leave it in the oven again for another hour at 400°f. But one coat is usually enough for the best result.

If the metal workpiece is too big to fit into an oven, you can bake the boiled linseed oil on the metal with a blowtorch. The procedure is the same. Coat the metal piece in boiled linseed oil and use the blowtorch for baking the oil on the metal.

But for this procedure, baking only once is recommended as it is usually enough. It would also be best to pay attention to the color of the metal as you torch it. Spraying the blue flame on an area for a short time should be enough to bake it on the metal surface.

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