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4 Tips for Using Boiled Linseed Oil Safely on Your Raised Beds

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Linseed oil in both it’s natural form (100% linseed oil) and boiled alternative, have long been used by woodworkers to add color and some degree of protection to raw wood. When it comes to vegetable gardens, you may be wondering two key things:

  • Is this safe to use where I will be growing my food.
  • Will it help protect the wood.

Let’s have a look at those very important questions. First, it helps to explain a little bit about what Linseed Oil is to begin with.

What is Linseed Oil?

Linseed oil is the oil extracted from flaxseed. It is also commonly called flaxseed oil or flax oil. It is sold, commercially, in a couple of different forms.

linseed oil

100% Natural Linseed Oil

100% Natural Linseed Oil can actually be manufactured and sold as a nutritional supplement. When processed properly, it is non-toxic and safe for human consumption. In fact, it is commonly packaged and sold as a supplement.

Boiled Linseed Oil

Boiled Linseed Oil is the form most commonly used as a wood coating. Traditional boiled linseed oil processing involves boiling the oil in containers with no air for several days. This causes the oil to thicken, dry quicker when applied, and become a more suitable substance for use on surfaces.

Truly boiled linseed oil can be very difficult to find. Because this process of boiling down the oil takes a lot of time, modern-day Linseed Oil manufacturers will add drying agents, hardeners, and plasticizers to help improve the performance of the product.

Depending on what is used by any particular manufacturer, these could be toxic…or not.

Reasons to Use Boiled Linseed Oil on Your Garden Beds

The big thing to consider before going down the path of using boiled down linseed oil is why do you want to use it in the first place? What do you hope will be the results and will this product give you the results you are after.

One of the great things about pure boiled linseed oil is that it is a non-toxic way to add color and some protection to your wood. I would be remiss, though, if I didn’t warn you that those effects may not be as long-lasting as you hope.

As an all-natural alternative to doing nothing, linseed oil will definitely help things to look nicer when it is first applied. Over time though, the wood will still fade and it will still rot.

To keep the wood looking nice you will need to apply linseed oil more regularly than you would if you used a more “chemical” based sealer. That’s a fair tradeoff for most people but one I wanted to be sure you were aware of!

vegetable garden

Is Boiled Linseed Oil Safe for Vegetable Gardens?

Pure boiled linseed oil that is chemical free is 100% safe for your vegetable gardens. Care should be taken to ensure the boiled linseed product used is free of chemical additives.

Any time you have any type of preservative coming into contact with your raised garden beds, it’s natural to be concerned about safety. The last thing any gardener wants is the possibility of chemicals leaching into the soil and then into the plants being grown.

The key is to find a product that is actually pure boiled linseed oil. It can be difficult. I found this one  that had great reviews.

When using any boiled linseed oil product that does contain chemical drying agents, stabelizers, or polymers, you’ll have to determine what you are comfortable with as far as the steps to take to keep your foods safe.

4 Tips for Using Boiled Linseed Oil on Garden Beds

1. Start with a clean surface.

Before adding any type of finish to wood you always want to start with a clean surface. Whether you are applying linseed oil to raw wood before you assemble your garden beds for the first time, or applying it to pre-existing beds out in the garden, you’ll want to make sure your surface is clean.

In the case of existing beds in the garden, you can use a wire brush or even end of a broom to knock off any dirt or mud from the wood. Once the surface is clean, you are ready to apply the product.

2. Apply generously

Applying boiled linseed oil is relatively easy. For wood that has not yet been assembled into garden beds, you can simply pour the linseed oil onto the wood and then wipe it off using a shop rag or other clean cloth.

For aged wood already in the garden, simply pour the oil onto your rag or dip your rag into a container full of oil and then apply generously. You can even use a paintbrush for the initial application.

3. Wipe off the excess

If you are using a rag to apply the linseed oil, you shouldn’t have too much trouble with excess. If you are using the paint brush method, it’s good to follow the paintbrush with a shop rag to mop up any excess oil.

Ideally you’ll have a nice, even coating of linseed oil applied to the wood’s surface.

4. Allow to Dry

The drying time for Linseed Oil will vary depending on the type you use. Here is a general guide for drying times based on James Wright’s video below.

Linseed Oil TypeDrying Time
Pure Linseed Oil5-7 Days
Store Purchased Boiled Linseed Oil24 hours
Vacuum Boiled Linseed Oil26 hours
Home Boiled Linseed Oil30 hours
1-Day Bleached Linseed Oil48 hours
3-Day Bleached Linseed Oil48 hours

Keep in mind that your actual drying time will depend on several other factors including the density of the wood, temperature, and how much oil was applied.

You will want to ensure the wood has enough time to dry before getting it wet or exposing it to water if possible.

Dangers of Using Boiled Linseed Oil

The biggest danger for using Boiled Linseed Oil is actually not a concern of toxicity as much as flammability. Boiled Linseed Oil is highly flammable. It is even possible for rags soaked in boiled linseed oil to spontaneously combust and cause a fire.

After using boiled linseed oil, great care must be taken to ensure that any rags used to apply it have been allowed to dry thoroughly before storing or even discarding in the trash.

In fact, discarding used shop rags into a trash can, often also containing wood and sawdust, is a fire waiting to happen. In fact, here is a great video showing the process of linseed oil rags combusting.

3 Steps to Properly Discard Used Linseed Oil Rags

  1. Squeeze out all excess oil back into the jar.
  2. Lay the rags out in a well-ventilated area to thoroughly dry.
  3. Discard or store only when completely dry.

Final Thoughts

The key takeaway here is remember to read the label so you can be 100% sure you know exactly what you are putting on your raised beds. Boiled linseed oil isn’t a replacement for using naturally rot-resistant materials like cedar. And above all, be very careful with how you discard any cloth materials used to apply it!

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