Both of the people think that these two products are the same but they are not. There are key differences between them. A wood putty is a flexible material that remains pliable even when it dries. While a wood filler is made using pulverized wood byproducts which becomes hard after drying.
The wood putty is mostly used to fill the small holes. On the other hand, the wood filler is made using wood dust or sawdust suspended in petroleum or water-based medium. The putty made with the water-based medium is used for indoor applications while petroleum-based is for outdoor use. However, both of them dry very hard and stick tightly to the wood. But they cannot improve the strength of joints.
As you can see that the putties use polyurethane or epoxy like synthetic material and cannot harden it like the fillers. It remains flexible and makes it easy to fill the nail divots and small cracks. Its best application is on the finished wood.
How to Apply Wood Filler?
Before applying the filler, you need to mix it well using a putty knife. New woodworkers often think that hey can load up the knife and slather it on. However, fillers are not very easy to slather because it is hard. If you are applying it on a softwood like pine, it is more difficult. Because the putty becomes harder than wood and makes it difficult to sand. So, be careful while applying it and use a small amount for filling a crack or joint. If you are working with petroleum-based filler then you need to work fast as it hardens quickly. On the other hand, water-based can stay wet for longer.
While applying the filler, press it with your finger so it can go deeper into the crack. After that, remove the excess with a dry cloth. But if there is any residue, you can remove it later with water or acetone. You need to give at least 30 minutes to harden the filler. After that, take sandpaper and rub it on the area in the direction of the wood grain. If you will do the opposite side, then it will leave scratches.
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