Name: DOWSIL 3-6559
Brand: Dow Silicones Corporation
SKU: DOWSIL 3-6559

Main features

Adjustable 1 to 5 Wt% Addition Level
4 to 12-Hour Cure Window
Surface/Environment Cure-Inhibition Management

Product Description

DOWSIL™ 3-6559 Cure Accelerator is a one-part, straw-colored liquid organoplatinum additive for accelerating the cure of compatible platinum-catalyzed Silastic™ moldmaking silicones. It is mixed at 1–5% by weight into the combined silicone base and curing agent. Within the Silastic E, J, L, M, and T systems covered by the supplied technical bulletin, increasing the accelerator level progressively reduces working time and cure time. The concentrated additive may also be applied to certain inhibiting surfaces or added in small amounts to help address surface or environmental cure inhibition. Addition levels must be controlled carefully because excessive accelerator can shorten the available working time to only a few minutes.

Key features

Concentrated organoplatinum additive: Uses the same general catalyst chemistry found in compatible platinum-catalyzed Silastic moldmaking silicone systems.
Adjustable addition level: Recommended at 1–5% by weight of the combined base and curing-agent mixture.
Controlled cure acceleration: Increasing the addition level reduces both working time and cure time in the identified compatible silicone grades.
400 cSt typical viscosity: Supplied as a pourable liquid with a typical kinematic viscosity of 400 cSt at 25°C.
Cure-inhibition support: May be used on certain inhibiting surfaces or in small additions where environmental contaminants interfere with normal silicone cure.

Applications / Suitable for

Accelerating the cure of compatible Silastic E, J, L, M, and T moldmaking silicones.
Treating certain cure-inhibiting surfaces before silicone molding.
Evaluating cure inhibition caused by contaminants in molding equipment, parts, molds, or the surrounding shop environment.

TDS, SDS & Technical Documents

Technical Specifications

No specifications available.

Additional Information

Silicone curing agents

DOWSIL™ 3-6559 Cure Accelerator

DOWSIL™ 3-6559 Cure Accelerator is a concentrated, one-part organoplatinum additive used to shorten the working and cure times of compatible platinum-catalyzed Silastic moldmaking silicones. Its adjustable 1–5 wt% addition range allows the cure schedule to be selected according to the silicone grade and available processing time.

One-part liquid additive Organoplatinum chemistry 1–5 wt% addition 400 cSt at 25°C

Container of DOWSIL 3-6559 Cure Accelerator, a liquid organoplatinum additive for compatible silicone moldmaking materials

As supplied

Material characteristics

Kinematic viscosity

400 cSt

Typical value at 25°C. The liquid form supports measured addition and incorporation into the mixed silicone system.

Relative density

1.00

Typical value relative to water, useful when planning material handling or volume-to-mass calculations.

Physical form

Straw-colored liquid

A one-part liquid additive with a slight odor.

Property	Value	Unit	Method / condition
Chemical nature	Organoplatinum compound	—	Product mixture
Physical state	Liquid	—	As supplied
Color	Straw-colored	—	Typical physical data
Odor	Slight	—	Typical physical data
Kinematic viscosity	400	cSt	Typical at 25°C
Relative density	1.00	—	Water = 1
Boiling point	>100	°C	At 760 mmHg
Flash point	>101.1	°C	Closed cup

Physical-property values are typical and are not guaranteed specifications.

Processing

Addition level and cure-time control

Add the cure accelerator only to compatible platinum-catalyzed Silastic moldmaking silicone systems. Select the concentration according to the required working time and cure schedule, and verify the result under the actual molding conditions before production use.

Recommended addition: Mix 1–5% by weight into the combined silicone base and curing-agent mixture.

Mixing sequence: Combine the silicone base and its curing agent, add the selected accelerator quantity, and mix thoroughly before pouring or applying the silicone.

Cure-time range: For the Silastic E, J, L, M, and T grades covered by the technical bulletin, 1 wt% produced listed cure times of 8–12 hours, 2 wt% produced 5–8 hours, and 5 wt% produced 4–6 hours, compared with 24 hours without accelerator.

Working-time range: Across the same listed grades, working time ranged from 78–105 minutes at 1 wt%, 40–70 minutes at 2 wt%, and 30–52 minutes at 5 wt%.

Addition control: Avoid excessive accelerator. The material is highly concentrated, and over-addition can reduce the working time to only a few minutes.

Technician weighing a small quantity of liquid cure accelerator into a mixed two-part silicone moldmaking compound

Measure the accelerator by weight and distribute it thoroughly through the combined silicone base and curing-agent mixture.

Storage and handling

Keep the material in properly labeled containers and store it in accordance with applicable local requirements. Avoid contact with strong oxidizing agents. Use adequate ventilation and follow the current safety documentation and workplace risk assessment when handling the product.

Managing cure inhibition

Localized surface inhibition

Sulfur-containing clays, certain woods, some plastics, and particularly some epoxy surfaces can interfere with the platinum-catalyzed cure. Where slight inhibition is confirmed, brush or paint the cure accelerator onto the inhibiting surface before silicone contact. Excess material applied to the surface is absorbed into the silicone during its normal cure schedule.

Barrier coating alternative

An inhibiting surface may alternatively be isolated with a suitable barrier coating. The supplied guidance identifies clear acrylic spray, oil- or latex-based paint, and thin petroleum-jelly coatings as examples. Confirm that the selected barrier treatment is suitable for the mold surface, silicone system, and required surface finish.

Environmental or gross inhibition

Machine oils, vapors, and other contaminants can settle on silicone mixing equipment, parts, or molds and produce sticky surfaces or slower cure. The preferred approach is to identify and remove the contamination source. When the molding operation cannot be isolated, a small controlled accelerator addition may sometimes reduce the observed inhibition.

Next steps

Evaluate cure acceleration for your silicone molding process

Krayden can help review the silicone grade, target working time, cure schedule, addition level, and potential sources of cure inhibition for your molding process. Contact us to discuss product selection, processing trials, technical information, or material availability.

Discuss Your Application