Slate, cushions and what holds a table true.

What the WPA asks of slate

The WPA tournament specification calls for slate at least 1 in thick, in three equal pieces, on a wooden frame at least 3/4 in thick. It also sets tight flatness limits: within 0.020 in along the length and 0.010 in across, no more than 0.030 in of extra sag under a 200 lb load at the center, and the joints within 0.005 in of a single plane once leveled. The BCA reproduction recommends the same three pieces, 1 in minimum, on a 3/4 in frame for tournament play.

Thickness

Sources give different ranges, partly because they describe different kinds of tables:

• Sawyer Twain: 3/4 in on entry-level tables, 1 in as the commercial and tournament standard, and 1.25 in as rare and generally not needed at home. A second Sawyer Twain article says 1.25 in shows up on some premium tournament tables.
• Wikipedia: home tables can use slate as thin as about 1/2 in.
• Bar Games 101: 3/4 to 1 in.

Total slate weight is also disputed. Seybert's says about 450 lb, Bar Games 101 says 400 to 600 lb, and Pro Billiards says more than 600 lb. Triangle Billiards warns that over long periods a slate table's weight can damage some floors.

One-piece vs three-piece

Three-piece slate can be leveled more precisely and is easier to carry through narrow doors and up stairs, according to Sawyer Twain and Pro Billiards. Billiard Factory says the bed on 8 and 9 ft tables is typically three seamed pieces that run under the rails. The tradeoff Bar Games 101 notes is that a seam between sections can show over time.

One-piece slate, per Pro Billiards, is typical of bar-style and coin-operated tables that seldom move, and it is the hardest kind to move. Diamond offers its Pro-Am in 1 in slate as either one piece or three. A retailer says one piece is the default and three pieces are offered for upstairs installations.

Backing, origin and checking a used table

Slate sits on a wood backing, and the cloth is stapled into that backing (Bar Games 101). Brunswick describes the Gold Crown VI bed as backed 1 in slate. Olhausen frames its slate in what it calls a Slate Liner, which it says reduces stress on the slate and lets the cloth be installed tighter.

Bar Games 101 names Brazil, China, India and Italy as the top four slate exporters. It says Italian slate is regarded as the highest quality and is marked OIS (Original Italian Slate), and describes Brazilian slate as more durable and Italian as softer and easier to work. Machining claims come from the makers: Brunswick says its slate is measured twice, exceeds BCA specifications, and has each side checked four times during machining and curing; Olhausen says its slate is diamond-honed and checked for flatness and bolt-hole placement.

To confirm a used table really has slate, look underneath. The bottom of slate is not covered, so you will see bluish-gray stone.

Non-slate beds

Billiard Factory adds that re-leveling a warped non-slate bed does not fully fix the warp, and new cloth only hides it for a while.

Cushion rubber and height

Cushions are elastic vulcanized rubber, natural gum or synthetic. The WPA sets the cushion nose height at 63.5% of the ball diameter, plus or minus 1%, which Pool Table Portfolio works out to about 1.429 in (36.29 mm) for a 2.25 in ball. The cloth-covered cushion must be 1 7/8 to 2 in wide, and in the WPA rebound test a ball has to travel 4 to 4.5 table lengths without jumping. The BCA reproduction adds that cushions must match three-cushion angles within one ball width either way.

Sawyer Twain says high-quality cushions use natural gum rubber and keep a consistent bounce over time. Named cushions are the makers' own: Brunswick uses SuperSpeed rubber, and Olhausen describes its Accu-Fast cushions as natural gum rubber made in the USA.

Cushion profiles: K-66 and K-55

The profile is the cross-section shape of the rubber. Pool Table Portfolio stresses that K-66 and K-55 are profile names, not rebound ratings, and that a replacement cushion has to match the rail cut the table was built for.

• K-66. Wikipedia and Black Label Billiards both call it the American standard. They disagree on its dimensions: Wikipedia gives a 1 3/16 in base and a 1 in nose height, while Black Label lists it as 1 3/16 in high with a 1 in base, the reverse. Wikipedia adds that with 2.25 in balls the nose sits 1 7/16 in above the slate.
• K-55. Black Label lists it at about 1.25 in high with a 1 1/8 in base, describes a sharper, faster rebound, and says it is used mainly on carom and European tables and on some high-end American tables. A retailer comparison says Diamond's Pro-Am and Professional both use K-55.
• Snooker. Snooker tables use an L-shaped profile, such as L77.

There is no fixed service life for cushion rubber. Before deciding the rubber is dead, Pool Table Portfolio says to check how it is attached to the rail, the condition of the cloth, and the nose height.

Leveling and installation

Built-in leveling varies by maker. A retailer lists the Brunswick Gold Crown VI with 22 built-in slate levelers, and Diamond uses a 22-point wedge leveling system. Olhausen says its frames are pre-fit, pre-leveled and squared at the factory and can be knocked down for difficult installs.

Pool Table Portfolio's installation order:

1. Pre-level the frame.
2. Set the center slate, then the head and foot pieces.
3. Shim each section.
4. Fasten the slate.
5. Fill the seams, only after the pieces are aligned.
6. Recheck level.
7. Install the cloth.

Its tools are a calibrated machinist's level and a 4 ft level or straightedge. On a Brunswick Sanibel, it says seams are filled with rock-hard putty or slate joint wax and scraped flush, and that body filler is not a substitute. The often-repeated claim that installers use beeswax could not be confirmed from any source we read. For the cloth, the WPA specifies relieving about 1/2 in of length and 1/4 in of width after stretching, with bed fasteners no more than 1 in apart and rail fasteners no more than 3/4 in apart, each going at least 3/8 in deep. Pro Billiards recommends professional installation and leveling for slate tables.

Moving a table

Seybert's guidance:

• Even within one room, plan on at least four strong helpers and dollies rated for at least 1,000 lb.
• Take it apart in this order: pockets, rails, cloth, slate, legs. The rail bolts cover the slate bolts, usually 3 to 4 per section about 18 in apart.
• Professional movers average about three hours to disassemble.
• To reuse the cloth, roll it on a tube instead of folding it, and reinstall it with new staples from head to foot.
• On reassembly, tighten rail bolts gradually in a star pattern.
• Re-level fully after any move, however short.