Module 4 — The Stack Gradient Framework

# Module 4 — The Stack Gradient Framework

> **Note:** "Stack gradient" is a conceptual teaching framework, not an
> industry-standard term. No manufacturer or ITTF organisation uses this
> language. The underlying *physics* is real and validated; the naming
> is ours for clarity.

## The Concept

If you plot stiffness from the core outward through the plies, you get a
"gradient profile." How abruptly or smoothly that gradient changes determines
whether the blade has a single unified feel, or whether you notice a clear
gear-change as stroke power increases.

### Three Archetypes

**1. Smooth Gradient (All-Wood Blades)**
```
Core [soft] → Sub-outer [slightly stiffer] → Outer [stiff]
```
No sudden stiffness jumps. Feel changes gradually with power.
The blade responds proportionally — more power in = predictably more out.
*Examples: 5-ply Korbel, Stiga Clipper, Tibhar Stratus Power Wood*

**2. Stepped Gradient (Inner Composite)**
```
Core [soft wood] → [INNER CARBON/ALC] → Outer wood [moderate]
```
At low power (soft shots, pushes), the carbon layer is barely engaged.
The outer wood plies dominate — feel is woody, controlled.
At high power (full-swing loops, smashes), the carbon "kicks in" — you
get an extra boost of speed and stiffness.

*Community description on Revspin.net:*
> "Lower gear: soft woody feel like no other ALC. When you swing hard,
> that's when the ALC kicks in providing an extra boost."
> *(Innerforce Layer ALC, jerem review)*

*Examples: Butterfly Innerforce Layer ALC, DHS Hurricane 301*

**3. Geared Gradient (Outer Composite)**
```
Core [soft] → Inner wood → [OUTER CARBON/ALC] → thin wood or no outer wood
```
Carbon is at or near the surface — the blade structure is "engaged" on
every single contact, even soft shots. Response is consistent, direct,
and speed-biased regardless of stroke power.

*Community description:*
> "Ball behaves similarly at the ends and in the middle. Very crisp on all
> shots — more precise feel."
> *(Viscaria, ControlledSpin review)*

*Examples: Butterfly Viscaria, Timo Boll ALC, Butterfly Boll TriCarbon*

## Which to Choose?

| Playing style | Recommended gradient |
|--------------|---------------------|
| Spin-heavy looper, all-wood feel | Smooth (all-wood 5-ply) |
| Transition player wanting control + occasional speed | Stepped (inner composite) |
| Flat hitter, blocker, mid-distance power game | Geared (outer composite) |

The stepped gradient is ideal for players transitioning off all-wood —
you keep wood feel at close-table distances while gaining speed when needed.