What does “post curing” do for a urethane casting?
Posted on 7/21/2014
Post curing any urethane plastic will enhance the physical and performance properties of the plastic.
Procedure; flat castings and simple shapes can be post cured outside of mold if placed on a flat surface. 3-d or complicated shapes should be post cured in the rubber mold to prevent distortion.
Following the normal cure cycle for the plastic (consult product technical bulletin), casting can be exposed to mild heat 150°F / 65°C for 2 – 4 hrs. Allow to cool to room temperature before demolding.
Increased Heat Resistance – To give the casting higher heat resistance, cure for two hours at 150°F / 65°C, followed by two hours at 212°F / 100°C. Allow to cool to room temperature before demolding.
Epoxy Resins – Offer the advantage of higher physical and performance properties vs. urethane resins. Epoxy resins also offer higher heat resistance properties. Many epoxy resins require heat curing at a minimum of 212°F / 100°C. For maximum heat resistance, post curing at 300°F / 150°C is recommended. Consult product technical bulletin for complete directions.
Sources Of Heat – What Are Your Options?
An oven is best for applying uniform heating, but use with caution.. We recommend that you do not use your kitchen oven. Mold making and casting should never be done in the home and accidents can happen. For example, applying too much heat to some materials may result in dangerous fumes being emitted and/or a material may melt resulting in a ruined oven.
The FAQ list is offered as a guideline and offers possible solutions to problems encountered during mold making and casting. No warranty is implied and it is up to the end user to determine suitability for any specific application. Always refer to the provided Technical Bulletins (TB) & Material Safety Data Sheets (MSDS) before using any material. A small scale test is suggested to determine suitability of any recommendation before trying on a larger scale for any application.