Polymerization
Polymerization is the chemical reaction that transforms the mixed Plastiform base and catalyst into a solid impression. It begins the moment the two components are mixed together and continues until the material reaches its final hardness.
Polymerization is a global process, if a product is cured on the outside part of an impression, it will be polymerized in it’s core at the same time.
There is one exception to this property. In very large impressions, if there is a temperature difference between one side of a part and the other, it can slow the chemical process on the colder side.
What Happens During Polymerization
Plastiform products are bi-component. The base and catalyst are chemically inactive while separated. When mixed in a 1:1 ratio, molecules from both components link together to form long polymer chains. This process is called cross linking.
The reaction has these characteristics:
- 01 / 04
No heat produced
The reaction is isothermal. The impression does not warm up as it cures.
- 02 / 04
No odor
No volatile compounds are released during polymerization.
- 03 / 04
No volume change
The mixed volume equals the final solid volume. There is no shrinkage or expansion.
- 04 / 04
Irreversible
Once cured, the impression cannot be melted or returned to liquid form.
Changing the ratio doesn’t change the polymerization time.
Do not mix Plastiform products at a different ratio than 1 for 1.
If you need faster / slower polymerization time for a product, contact us.
Polymerization Time
Plastiform products polymerization time is indicated in minutes at 20°C on the product label and technical sheet.
Time is temperature dependent. Polymerization speed changes with ambient temperature:
| Temperature | Effect |
|---|---|
| Above 25°C | Faster polymerization. Working time is reduced. |
| 15°C to 25°C | Optimal range. Nominal polymerization time applies. |
| 10°C to 15°C | Slower polymerization. Allow extra time before extraction. |
| Below 10°C | Significantly slower. |
| Above 50°C | Outside functional range. Performance is not guaranteed. |
The stated polymerization time on the label is valid only at 20°C. If your workshop is significantly warmer or colder, adjust your timing accordingly.
How to Know Polymerization Is Complete
For most products, the impression is ready when it no longer feels tacky and resists light finger pressure. If your nail doesn’t mark the surface of the impression it’s ready for extraction.
We recommend leaving the impression to polymerize for several minutes until it reaches its final rigidity before extraction, especially for roughness measurements.
Practical indicators:
- The surface is no longer glossy or wet looking.
- A light press with a fingernail does not leave a mark.
- The impression detaches cleanly from the part when pulled.
Safety margin: Wait 1 to 2 minutes beyond the nominal time before extracting. This ensures complete curing and the replica reach its final hardness.
