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The Seam Line Nobody Photographs
Every cast piece has a line down its side. How it gets there, what we do about it, and how to tell good seam work from bad in a photo.
If a figure is cast rather than printed, it came out of a mould that had at least two halves, and where those halves met there’s a line. Every cast object has one. The question isn’t whether it exists, it’s whether you can find it after the piece has been finished.
How it forms
Resin pushes a little way into the gap between mould halves and sets there, leaving a thin raised ridge running the length of the piece. On a 120 cm figure that’s a line the full height of the body, usually down the side, sometimes down the back depending on how the mould was split.
Mould halves also shift slightly under pressure. When they do, the two sides of the line don’t line up perfectly and you get a small step, maybe half a millimetre, running alongside the ridge.
Removing it
Cut the ridge back with a blade held flat, then sand through grits, then check under a raking light, then fill if there’s a low spot, then sand again. The raking light is the part that matters. Under flat front-on lighting a bad seam is invisible. Hold a lamp at a low angle to the surface and the same seam throws a shadow like a scratch.
What you can’t do is sand it away without also flattening the sculpted detail around it. Over-sand a seam and you end up with a subtle flat running down the side of the figure, which is worse than the seam was, because a flat reads as a modelling error while a faint line reads as a mould seam and nobody minds.
Reading it in photos
Look at the product shot, then look at the shadow side of the same figure in any photo taken under a lamp rather than a softbox. If the line disappears in both, the seam work is good. If there’s a visible step in the paint where the colour changes level, it was filled rather than properly levelled, and paint over filler always gives it away eventually.
We photograph our pieces under soft, even lighting, which flatters them. It also means if you want to judge the seam work yourself, the honest way is to see one in person under a normal household lamp.
Patterned colourways are the unforgiving ones, since a seam running across a colour boundary has to line up on both sides. Patchwork Panda is about as hard as this gets.