What is slate?
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. – via Wikipedia
Slate is a dense playfield material with a low water absorption index (0.4%) making it nearly waterproof. Moisture is important in the wear on a table overtime but it’s also important during the installation process. Slate can crack if it is too dry when tightening down screws.
Slate is important because it gives the ball a frictionless roll that is smooth and untampered with by peaks or valleys in the table. Depending on the mineral content of the location the slate was sourced from (Italy, Brazil, China, Spain, Wales, etc.), slate is found in many colors. Billiard slate is most commonly gray or black. Now, let’s talk a little about the milling process.
The Milling Process
The playfield of a pool table is made out of either slate or non-slate material. Slate being the superior and most common, is mined from the ground. From there, the slate is cut, sanded (or “honed”) flat, then backed with a wood or MDF frame.
The sanding process is very important to the leveling of a table because this can create or eliminate natural high/low spots in the slate. Large 5’ sanding disks are used to properly flatten a table while smaller 6” disks are sometimes used. These smaller 6” disks create problems because the disk can only smoothen a small area at a time, creating grooves and rifts in the slate. You can tell what size disk was used by looking for patterns on the slate. Sanding marks are an indication of improperly honed slate as evidenced by the back and forth strokes that can be seen.
Moisture is another key factor in the milling process. Slate with low moisture content is prone to cracking and chipping because it becomes too rigid. This is one of the reasons Brazilian slate is preferred over Italian slate.
One piece vs Three piece Slate
What’s the difference between 3 piece slate and a 1 piece slate pool table?
A one piece slate table is built using a single piece of slate while a three piece slate table is divided into three sections. Effectively, the one piece slate table doesn’t have any seams while the three piece slate table has two seams. Properly milled three piece slate starts as a one piece slate and is then cut into three pieces so essentially, you’re getting a single piece of slate that’s just cut into pieces.
Tip: Look for a small semi-circle chalk mark on a three piece slate table to tell that you have a “matched set.” When the pieces originated from the same piece of slate, the chalk marks should line up perfectly when assembled!
Almost all high quality tables use three piece slate because it offers several advantages. The most important being the ability to accurately level a three piece slate table. Three piece slate is also much easier to move and less inclined to warping over time like one piece slate does due to weight. Three piece divides this weight into smaller portions making it better for the table in the long run.
Read More: 1 Piece vs 3 Piece Slate Pool Tables
One Piece Slate
- Built using a single piece of slate
- Seamless playfield
- Extremely difficult to move
- Mostly used for coin-op tables found in bars or clubs
- Sag or warp overtime due to the weight
Three Piece Slate
- More accurate leveling
- Easier to move
- Does not sag over time
- More common than one piece tables
- More common in larger tables
Slate Thickness: 3/4 Slate vs 1” Slate
Slate thickness is far more important than the number of pieces the table uses. ¾” slate is good and 1” slate is the best. Sometimes you’ll find lower quality tables that only use ½” slate. Thicker slate has fewer deficiencies and is usually permanently framed with wood to provide additional support when installed on top of the pool table cabinet. Heavy slate will also prevent the table from moving during vigorous play.
Read More: Pool Table Slate Thickness
Slate vs Non-Slate Pool Tables
What’s the difference between slate and non slate pool tables?
If you want the balls to roll straight when you hit them, then you will want a slate table plain and simple. Slate is the only play surface that can be precision leveled to 1/10,000 of an inch. This attention to detail ensures the ball rolls in a straight line. Non-slate tables are more appropriate for pool tables that will be used for small children as toys.
Where to Buy Slate Pool Tables?