diff --git a/experiments/MODEL_SLICES.md b/experiments/MODEL_SLICES.md
index d705323..44fcafa 100644
--- a/experiments/MODEL_SLICES.md
+++ b/experiments/MODEL_SLICES.md
@@ -86,6 +86,16 @@ projecting reference positions of the deformed cut would be a different curve.
 An exactly coplanar surface patch is reported as unsupported instead of being
 silently drawn as a unique intersection curve.
 
+The tetrahedral subdivisions are conforming inside each parent hexahedron,
+but their face diagonals are not made globally consistent across differently
+oriented neighboring elements. Boundary faces are triangulated independently
+as well. On a curved shared face, these choices can produce slightly different
+chord approximations: small gaps or overlaps between neighboring element fills,
+or a mismatch between the colored edge and the independently drawn outline.
+Deterministic ownership of a coincident planar face does not remove this curved
+interface approximation. These image artifacts must not be interpreted as
+physical gaps, jumps in geometry or an additional density feature.
+
 Curved cuts are displayed using straight triangles and boundary chords. Field
 colors are piecewise linear on those triangles, not exact values throughout
 their interiors. Root tolerances, maximum physical-plane residuals, sampled
@@ -96,6 +106,15 @@ between subdivision vertices can be missed; compare subdivisions for image
 stability. This visualization does not certify pointwise positivity or exclude
 small unsampled features.
 
+Before interpreting an actual FEM image, export the same saved state and plane
+at two subdivision counts, for example 6 and 12 (or 4 and 8 for a first bounded
+check). Compare the outlines, element-interface seams, sampled chord errors and
+the visible density/enthalpy structure at the same axes and color ranges. The
+pure geometry and plotting controls below do not test differently oriented
+neighboring curved hexahedra and do not replace this export refinement check.
+Globally consistent face triangulation would remove the diagonal mismatch;
+it is not implemented in this bounded diagnostic.
+
 ## Checks
 
 Every export runs pure geometric controls: unit-cube section area, integration