In most plywood units, once the board comes out of the sanding machine, it looks clean and uniform. At that stage, many people assume
the surface is already ready for dispatch or further finishing.
But in practice, there’s still one important step that follows — chemical dipping, and then brush sanding.
Note :Kumar Engineering offers two variants of brushing machines:
Double Head (Both Side): Equipped with two brush rollers on the top and two
on the bottom, making a total of four brush rollers. Check the tech spec
here .
Triple Head (Both Side): Equipped with three brush rollers on the top and
three on the bottom, making a total of six brush rollers. Check the tech
spec
here .
What Happens During Chemical Dipping?
After sanding, plywood sheets are often dipped in a chemical solution. This is mainly done to protect the board from:
- Termite attacks
- Wood-boring insects
- Fungal growth
- Moisture-related degradation
- Microbial or biological decay
The idea is simple — make sure the chemical reaches every part of the board, including edges and pores. Dipping ensures full
coverage, which is difficult to achieve with spraying or manual application.
But Dipping Changes the Surface
Once the board comes out of the chemical bath and dries, the surface is no longer the same as it was after sanding.
You’ll usually notice a few things:
- The surface feels slightly rough
- Fine wood fibers tend to rise
- There may be a thin residue or unevenness in some areas
Even though the protection is done, the finish quality drops at this stage.
Why Brush Sanding is Needed After This
This is where brush sanding comes into the picture.
Unlike a regular sanding machine, a brush sander works gently on the surface. It doesn’t remove material
aggressively — it just cleans up the surface after treatment.
1. It Brings Back Smoothness
The main job is to remove the raised fibers that appear after dipping.
Without this step, the board may feel rough to touch, which is not acceptable for most applications.
2. It Removes Chemical Residue
Sometimes a slight layer or unevenness is left behind after drying.
Brush sanding helps in evening out the surface without damaging the ply.
3. It Maintains Thickness and Quality
Since brush sanding is light and controlled, it doesn’t affect the board thickness like heavy sanding would.
This is important, especially when you’re working with calibrated boards.
4. It Improves Final Appearance
Whether the plywood is to be laminated, polished, or used as it is, surface finish matters.
A properly brush-sanded board looks more uniform and professional.
Why Not Skip It?
Some might think this step can be avoided to save time.
But in reality:
- The board won’t feel smooth
- Finishing quality will suffer
- Customers may notice the difference
In many cases, skipping this step leads to complaints or rework.
Conclusion
In plywood manufacturing, every step builds on the previous one.
- Sanding gives you a clean base
- Chemical dipping gives you protection
- Brush sanding brings back the finish
It may look like a small step, but it plays a big role in delivering a board that is both durable and well-finished.
