[Bob]

Hi. I’m trying to embed an object in a large paperweight (7.5″ x 3.5″ x 3″). I’ve done a couple of test casts and I have a few problems. I’m using Castin’ Craft Clear Polyester.

First, I can see the border between separately poured layers. I let each layer cure before pouring the next one. Would pouring the second layer sooner work better?

Second, the final, top layer sometimes has a wavy surface.

And finally, the top layer ends up with a meniscus along the sides. Is there a way to avoid this?

Thank you.

[Katherine Swift]

Hi Bob,

If you pour your next layer of resin before the first layer has fully cured, it will minimize the lines you see.

Unfortunately, you are going to have a wavy surface when using polyester casting resin. It is not self-leveling and this occurs frequently.

The meniscus you describe also happens when casting resin into a mold. However the physics of it works, the resin wants to ride up the edge. The good news is that you can sand your casting to get rid of the ridge and wavy surface. Start with a coarse wet/dry sandpaper, then end with something 1000 grit or higher to get the surface smooth again.

[Bob]

Thank you, Katherine. To avoid the waves and meniscus, would you recommend I use a different resin? Does the size of my cast (7.5 x 3.5 x 3) affect what resins I can use?

[Katherine Swift]

Hi Bob,

An epoxy would be better in terms of controlling the waves, but they are all going to create the meniscus on the edge of the casting where the resin meets the mold.

You can use most any polyester or epoxy resin with the mold, but the amount you mix at once is going to vary. Each manufacturer should share the minimum and maximum mixing amounts for the resin. We share that information for the resins we sell in the PDF at this link: https://www.resinobsession.com/resin-frequently-asked-questions/resin-casting

[Bob Alexander]

Thank you Katherine!

[Author]

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