Behlen Paste Wood Filler:
Selection of a good paste wood filler is key to getting a mirror finish on your instrument. I have experimented with this process quite a bit and have developed a procedure that really works, but it does take some time and patience to complete.
First of all let me say that the decision to select a good wood filler will pay you back many times over. I prefer the use of an oil-base filler as it gives me a lot more time to work. Also, by remaining in a liquid state somewhat longer, it allows you to work it deep into the wood pores, and that is essential to prevent later collapse of the filler or sanding through it.
Why a Wood Filler In Important:
Most of the hardwood such as Rosewood, Mahogany, Walnut, and many more are referred to as open-grain woods, in that there are openings or pores that are evident in the wood even after finish sanding is completed. Certain woods are closed-grain such as Maple, Birch and all of the conifers including Sitka Spruce, Cedar and Redwood. These woods do not need, nor should they have a paste filler applied to them.
Why can’t you just fill-up the these pores with consecutive build coat of sealer or lacquer? Well, you can but…..What happens is when you get your finish nicely sanded very flat and later buff it out you will find that in a few short weeks or even days you will begin to see pits forming in your finish. That is the clear finish coats actually shrinking in the pores and it sucks the outer finishes down as well.
Therefore you need to get a colored, non-shrink material worked into the pores so you have a absolutely level, non-shrink surface on which you can spray your finish coats. This is where the oil-based wood filler can give you just that. Just one small caveat though. You need to exercise patience to give this filler time to thoroughly dry and then re-apply to get the great level finish.
How to Work With Wood Fillers:
The wood filler is applied over the sealer coats and just prior to any stain that would be placed on the guitar. Then the finish coats are layered over this succession of finish products.
As much as I love working with the oil based fillers, if you intend to apply stain to your instrument, go with a water based filler instead. You will have much better success.
If you are a novice, to this whole procedure, I would recommend that possibly do a bit of experimentation before you forge ahead and slap this stuff on your first instrument that you have been working of for weeks, or possibly suffer from having to strip off the sealer coats and start with bare wood once again. All you have to do is prepare some scrap wood of the same type you are working with and practice application of the filler. The trick is removal of the excess filler at just the right time to be successful.
Wait too long and you can;t hardly get it off. Don’t wait long enough and your results at pore filling are poor at best. I will write an article on how best to tackle the wood filling operation to give you some guidance.
Oil Based Wood Filler – The Advantages:
- It dries much slower than the water based variety, so it is much easier to apply.
- This filler type has been around a long time and it is will give very reliable results.
- There are a wide variety of color available.
Oil Based Wood Filler – The Disadvantages:
- Staining of the guitar finish, which takes place after the wood filer is applied is very difficult.
- If you sand through, it is difficult to repair with a oil filler.
- Oil based wood fillers will take several days to dry.