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Ensuring all seams in your mould box are properly sealed is essential when working with resin or polyurethane. Even tiny gaps can quickly result in leaks, wasted material, and ruined castings. Here are practical tips for creating a leak-free set-up.
Why Seam Sealing Matters
Lack of proper sealing leads to resin escaping from the mould box, causing mess, loss of product, and flawed moulds. Resin and polyurethane are both highly fluid prior to curing, making it especially important to inspect every edge and corner of your mould box for potential gaps.
Materials and Methods for Sealing
Common sealing solutions include using a hot melt glue gun, modelling clay, or high-quality masking tape on the interior seams before pouring your silicone. Press these materials firmly into all corners and joints, creating a smooth, continuous barrier. For critical or complex moulds, you may opt for a silicone caulk, applied sparingly. Allow your seal to set fully before introducing your casting material.
- Inspect both inside and outside seams for complete coverage.
- Check the seal’s integrity by adding a small amount of water first; remedy any leaks before proceeding.
Handy Tips and Product Recommendations
Selecting the right silicone for your moulds helps too—products like “Pure Mould” Translucent Liquid Silicone Rubber offer excellent flow and fine detail transfer, but will escape through any seam that isn’t tightly sealed. Use a good release wax for easy demoulding once your piece is cured, and choose your mould box material to match your project.
When This Matters
Sealing seams is vital for any open mould box, but it’s especially important when making highly detailed or deep moulds, or when using high-value silicone and resin. A small amount of prep work can save time, cost, and frustration later on.
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Related guides
By taking a little extra care to seal every seam in your mould box, you’ll enjoy more reliable, professional results with your polyurethane and resin casting projects. For a full guide to creating resin moulds for polyurethane, visit our main page.