Resin: separated layers and parts split in half

Likely causes

In order: the most frequent cause comes first.

1. 01Insufficient exposure: layers do not bond with the needed strength
2. 02Resin shrinkage on curing, which creates internal stresses between layers
3. 03Excessive peel force from a large cross-section
4. 04A loose or worn FEP film, which increases suction on lift
5. 05Cold resin: below 18–20 °C viscosity rises and the print fails

How to fix it

Apply one fix at a time and reprint the same test part. Changing three settings at once tells you nothing about which one worked.

1. 01

   Increase normal-layer exposure

   Easy

   Manufacturers give ranges: Anycubic publishes 2.5 to 3 seconds for its Standard Resin V2, 2 to 3.6 for ABS-Like 3.0, 2 to 2.5 for Water-Wash 2.0 and 1.5 to 3 for Tough 2.0. Raise in 0.2-second steps until layers stop separating, without overdoing it and losing detail.

2. 02

   Hollow the part and add drain holes

   Medium

   A solid part has large cross-sections that multiply peel force on every layer. Hollowing it to a 2–3 mm wall reduces that force and resin consumption too. Drain holes are mandatory: without them liquid resin stays trapped inside and later bursts the part.

3. 03

   Tilt the part and check the FEP film

   Medium

   Tilting 20 to 30 degrees reduces the area that peels at once. Also check the FEP film's tension: it should sound like a drum when tapped gently. An FEP with white marks, scratches or slack needs replacing.

4. 04

   Warm the room or the resin

   Medium

   Prusa recommends keeping resin between 18 and 32 °C and warns that below that range viscosity changes. On a winter night in Toluca, Chihuahua or Puebla, a resin printer in an unheated room fails for this reason rather than because of its settings.

How to prevent it

• —Always hollow large solid parts and give them drain holes
• —Check FEP tension before every long print
• —Shake the resin bottle for about ten seconds before filling the vat
• —Do not print resin in a room below 18 °C

Sources

1. [1]De-lamination / separated layers (SL1/SL1S) | Prusa Knowledge BasePrusa Research · Manufacturer · accessed July 27, 2026
2. [2]Resins | Prusa Knowledge Base (temperatura de la resina 18–32 °C)Prusa Research · Manufacturer · accessed July 27, 2026