Finishing a wood bowl is an important step. It allows you to preserve the finished product and provide a food grade coating which allows you to actually use it for what it’s meant.
Although there are many products out there, beginners still struggle to find the right technique and food grade options to finish their bowls. Furthermore, wood turners often find it difficult to achieve a satisfactory finish and will resort to either one single finish or the one they are most familiar with. This approach may work for certain pieces but does not account for the different ways the wood must be handled depending on its final use.
In this article, we will discuss the different finishes available for bowl turners, their advantages and the proper techniques to apply them to the finished product.
When to Use a Wood Sealer
By definition, any finish which forms a protective layer on the wood surface can be used and considered as a sealer. Some coatings, called “self-sealing” are considered to accomplish this task extremely well. On the other hand, some of the other finishes are not as effective and benefit from a separate sealer coat.
Oil-based and Shellac finishes, are very effective on their own and do not require any special sealer. Many woodworkers prefer to use a thinner mix for the first coats in order to apply them in quick succession. This allows for quicker drying and sanding time. However, it is strictly a personal choice and does not seem to have a great impact on the finished product or the protective coat.
Lacker and water-based coatings work much better when applied over a sealer. The proper sealer compound will lock in the harmful oils and waxes, reduce the number of coats needed by preventing excessive absorption, improve adhesion, and reduce grain raising.
The type of wood you have on hand is also impactful. With denser woods, it’s typically possible to completely omit the sealer. This is due to the fact that the fibers will not absorb the subsequent layers. On the opposite side, we have porous woods, which can greatly benefit from the right sealer. The coat will seal the pores and prevent the lacquer from being absorbed by the surface.
What is and When to Use a Sanding Sealer
The term “sanding sealer” has surfaced within the woodworking industry quite recently. However, there is quite a bit of confusion as to what it really is, when it is required and how to apply it. It is also important to recognize that the term itself means different things if you ask distinct woodworkers and finishers.
The reality is that sanding sealers have been heavily marketed by finish vendors, but it is not as effective as advertised. Most communities of woodworkers and woodturners agree that it’s not needed in most cases. Furthermore, it can negatively impact your product if it’s not used and applied correctly. Our general rule of thumb is to avoid sanding sealers unless you absolutely require it.
In essence, sanding sealer was developed to solve one particular problem. It is used to add zinc stearate, a type of chemical base, to lacquer. This causes the lacquer to build up faster, causing porous wood to seal quickly and better. The affected sealer will also subject itself to sanding easier since it does make the substance softer.
The Importance of Food Grade Sealers
Reaching out to chemists, regulatory agencies, finish manufacturers, finishing experts as well as woodworkers, it was found that there are several finishes which are deemed to be food grade. However, just like with everything else in life, there are compromises. A lot of food-safe finishes simply don’t hold up to the same levels of protectiveness as their hazardous counterparts.
The application of drying oils onto wood will cause it to penetrate the fibers and cause the material to harden. Drying Oils include linseed, tung and diluted varnish. They can also be found under the designation of wood sealers. They provide some of the most beautiful finishes for wood because of their glossy look and smooth feel. The oils also prevent moisture from penetrating the wood and make it much easier to clean the surface from any other contaminants.
These types of sealers are much easier to apply than some of the other finishes.
Applying Boiled Linseed Oil Finish
Linseed oil will provide you with a finish that is slightly less glossy than some of the other oils, but it will make the wood’s natural colors stand out.
To apply the oil, simply dampen a piece of cloth or paper in oil and apply a thin layer onto the wood. Let the surface dry for about 10 minutes. At that point, check the coat and even out any oil which gathered as a pool. Repeat the process every 10 minutes for an hour. At the end of the hour, completely wipe the oil from the surface. Let the surface dry for 24 to 48 hours. Apply the second coat; you should not need as much oil this time since the wood will not absorb the same quantity. Let the wood rest for 24 to 48 hours. If there are any dry spots left at the end of this, reapply another coat.
Applying Danish Oil Finish
Oils are a great finish as mentioned above. They will preserve the wood, keep it looking natural and allow you to consume food with or within your creation. Below is a simple guide on how to apply danish oil to a finished product.
- Start by applying a generous coat to your bowl. This can be done with a brush, cloth or piece of paper.
- Allow the bowl to rest while the oil flows down and covers the surface. The oil will penetrate the surface of the wood while it is resting.
- Using 400 grit sandpaper, begin turning the bowl at a low speed and sanding down the surface. This process will generate small particles which will help the oil create a nicer finish by filling in every single gap.
- Continue to sand the surface until you notice a thick slurry covering the wood. Give yourself another 5 minutes of turning.
- Clean the bowl with a cloth or paper towel, completely removing the coat of dust in the process.
- Leave the piece in a dry environment to dry for 24 to 48 hours. Ideally, cover the piece to prevent particles from coming into contact with the surface.
- Apply a second coat by brushing it on as in the first step.
- Let the bowl dry for about 24 to 48 hours.
- Repeat subsequent coat applications until the desired result is achieved.
- (Optional) Apply wax to the surface.
Nondrying oils will include varieties of vegetable and mineral oils which will penetrate the wood. Vegetable oil finish is an excellent choice for your bowls as it is completely edible. You’ve probably guessed that these are your oil, corn, peanut and sunflower oils. The less commonly talked about, yet very effective, oil is walnut oil.
Mineral oil typically comes from petroleum and may be used for food grade items. However, not all types of mineral oils will be free of additives. Make sure to read the label carefully before using this type of finish on your kitchen creations.
The natural oils need to be applied in heavy coats due to their ability to penetrate the wood. They are quite easy to apply and are popular among woodworkers of all skill levels. That being said, this oil will go rancid over a period time. Although it’s not harmful to your health, the odor can be uncomfortable to bear. These pieces will need to be dried for several weeks before they can be used.
Paraffin Wax is an excellent finish for pieces which will come in contact with food.
It is also a very cheap and easy to use finish. In case you didn’t catch it by the name, paraffin wax is the substance which comes from regular household candles. The application process is slightly more complex than the ones we described above, but with a proper guide, you simply can’t go wrong.
Applying Paraffin Wax Finish
Sand Down – Once you have completed turning your project, use sandpaper to give it a smooth feel.
Apply the Wax – As the lathe is still turning, simply touch the surface of the wood with paraffin wax. This will melt it and leave a thin coat which will penetrate the surface.
Remove Excess Wax – With a dry paper towel, remove the excess wax from the surface. Simply place the towel against the wood to once again melt the wax with friction and remove the unneeded excess.
Enjoy the Finish – If you aren’t satisfied, apply a second coat. However, if thoroughly applied, the wax should penetrate the wood very well. Stop using the lathe and enjoy your project.
Warning About Food Grade
Choosing the right food grade finish can be challenging. On one side, you have the beautiful yet toxic substances, on the other you have the luxury of using your creation, but it simply doesn’t look as good. Whatever finish you choose, if you go the food grade route, you need to make sure that it is in fact safe. It may appear like a great idea, but avoid scuffing at the ingredients list; that’s definitely not something you want to compromise on.
Lastly, if you have any doubts about a product, double check the label, contact the manufacturer, contact the Food and Drug Administration or speak to a local representative.