Metallic stearates are among the most quietly useful additives in plastics. They rarely get top billing in a formulation, yet remove them and a PVC compound can stick, scorch, plate out or lose colour. A metallic stearate is simply the metal salt of stearic acid — a fatty-acid soap — and the metal you pair it with decides what job it does best. This guide covers the three we manufacture: calcium stearate, lead stearate and dibasic lead stearate.
What metallic stearates do
In PVC, a stearate usually wears more than one hat at once:
- Lubricant — both internal (improving melt flow and lowering viscosity) and external (reducing friction against hot metal surfaces and preventing sticking).
- Acid scavenger / co-stabilizer — mopping up trace hydrogen chloride (HCl) released as PVC heats, which supports the primary heat stabilizer.
- Release and anti-caking agent — in plastics, rubber and powder handling.
That multi-functionality is why stearates appear in almost every PVC recipe, whether the primary stabilizer is lead-based or calcium-zinc.
Calcium stearate
Calcium stearate is the workhorse — a fine white, non-toxic powder used far beyond PVC. In a PVC compound it acts as an internal lubricant and a co-stabilizer, improving flow and scavenging acid. Being heavy-metal-free, it is the stearate of choice for calcium-zinc systems and for any application with toxicity limits.
Typical uses:
- Co-stabilizer and internal lubricant in rigid and flexible PVC
- Acid scavenger in polyolefins
- Release and anti-caking agent in masterbatch and plastics
- Matting and flow additive in paints, plus a processing aid in construction chemicals
Lead stearate
Lead stearate is a lubricating co-stabilizer used specifically in lead-stabilized PVC. It boosts heat stability and improves flow during extrusion and moulding, and is commonly paired with primary lead stabilizers such as tribasic lead sulphate. Because it contains lead, it is confined to applications where lead systems are still permitted — notably some wire and cable compounds — and is not used for potable-water or food-contact PVC.
Dibasic lead stearate (DBLS)
Dibasic lead stearate combines stronger long-term heat stabilization with lubrication in a single additive. The "dibasic" form carries more stabilizing capacity than normal lead stearate, which makes it valued in rigid PVC for cables and profiles where both heat stability and good electrical properties matter.
Choosing the right stearate
| If you need… | Consider | Why |
|---|---|---|
| A non-toxic lubricant / co-stabilizer | Calcium stearate | Heavy-metal-free; food-contact friendly |
| Extra heat stability in a lead system | Lead or dibasic lead stearate | Co-stabilizing lubricant boost |
| A cable or rigid-profile co-stabilizer | Dibasic lead stearate | Heat stability + electrical properties |
| A masterbatch or paint additive | Calcium stearate | Dispersion, release, anti-caking |
The right choice depends on your primary stabilizer, your application and any regulatory limits. If you are building a lead-free recipe, calcium stearate is almost always part of the answer; if you are running a lead system, the lead stearates earn their place. For the bigger decision behind all of this — lead versus calcium-zinc chemistry — see our lead vs calcium-zinc stabilizer guide, and for packaging it all into one addition, our note on one-pack vs individual systems.
We manufacture calcium, lead and dibasic lead stearate as a full metallic stearates range. Tell us your compound and process and we will recommend the grade and dose.