Back-plane issues on a resin print (the flat “back” side of a box) are super common—and usually come down to suction, orientation, or support strategy. Here’s how to fix it depending on what you’re seeing:

### If the back surface is wavy / sagging - Cause: Large flat area parallel to the build plate → suction + poor support - Fix:

1. Tilt the model 20–45° instead of printing it flat
2. Avoid any large surface being parallel to the plate
3. Add more medium supports across that back face (not just edges)

### If you get layer lines, ripples, or “elephant skin” - Cause: Peel forces + insufficient rigidity during lift - Fix:

1. Increase lift distance slightly (e.g. +1–2 mm)
2. Reduce lift speed
3. Increase exposure time slightly for better layer bonding
4. Check FEP is tight and not worn

### If the back plane has holes or missing patches - Cause: Suction failure or supports failing - Fix:

1. Add drain holes if it’s a hollow box (critical!)
2. Thicken walls to at least 1.5–2 mm
3. Add internal supports if hollow
4. Ensure supports connect to the problem area directly

### If it’s rough or has support scars - Cause: Supports placed directly on visible surface - Fix:

1. Re-orient so the back face is not the support side
2. Use lighter supports + increase density instead of heavy ones
3. Place supports on edges or hidden faces

### If it looks compressed or distorted - Cause: Too much suction force during peel - Fix:

1. Add vent holes
2. Tilt more aggressively
3. Use “hollow + holes” instead of solid block

### General best practices for boxes - Never print a box flat like an FDM print - Tilt + hollow + drain holes is almost always the correct approach - Think in terms of minimizing cross-sectional area per layer

If you want, send a photo or your slicer orientation and I’ll pinpoint exactly what’s going wrong 👍