# When Fisheyes Aren't Contamination **Category:** Troubleshooting\ **Type:** Paint Behavior Diagnosis\ **Field Diagnosis:** When Repriming Doesn’t Fix It\ **Related Topics:** Surface Wetting, Cratering, Internal Product Failures *** ### Summary Not all fisheyes are caused by surface contamination. This field note documents a case where apparent contamination issues were actually traced to internal product formulation problems. The key diagnostic breakthrough came from recognizing that the defect persisted across multiple surface preparations and primers. ### Case Study: The BIN Shellac Test A kitchen cabinet refinisher encountered fisheye (crater-like) defects and initially assumed they were due to surface contamination. The typical response followed: > "Noticed contamination on my other primer so I shot 2 coats of BIN shellac... still have moon craters..." This statement contains a crucial diagnostic clue. When BIN shellac—known for its exceptional blocking and sealing properties—fails to eliminate the problem, contamination is unlikely to be the cause. ### Key Diagnostic Principle **If the problem follows the topcoat, regardless of what's underneath, it's not the surface. It's the topcoat.** When the same defect appears after switching primers and using BIN shellac, the common factor becomes clear: the topcoat itself. ### Understanding Internal Product Failures If you determine the topcoat is causing the issue, the fisheye or dimpling often points to one of two internal problems: **an overloaded defoamer or an imbalanced formula.** When the defoamer is too strong or used in excess, it can lead to siliconized kick-out, where parts of the formula repel each other during film formation. This creates craters that mimic surface contamination, even when the surface is clean. An imbalanced system can also present other issues such as dimpling at high film builds, increased shear resistance during application, poor rebound or leveling after movement, and weak surface wetting where the paint pulls back instead of laying down. These symptoms are unrelated to poor prep; instead, they indicate the topcoat is rejecting itself from within. ### What's Happening at the Surface Think of the difference between a meteor crater and a fisheye: * A **meteor crater** is caused by something hitting the surface * A **fisheye** is caused by the paint pulling away from itself The paint film attempts to level and form a smooth surface, but the overloaded defoamer repels parts of the formula (resins, pigments, or water). This rejection causes a hole to open up as the paint pushes away from that spot. The edges dry first, locking in the crater shape while the center remains lower. It's not an impact, but rather an expulsion where the film breaks apart because it cannot maintain adhesion and tension at that location. ### Field Test: Glossy Card Stock Method If you suspect the topcoat is the problem, here's a quick way to verify: Take a piece of glossy card stock—something smooth and nonporous—and apply a small amount of the topcoat. Draw it down gently and observe the surface. **Results:** * If it forms dimples, fisheyes, or crawls on the clean card, that confirms the product issue * If there's no contamination present and it still fails, the issue is almost certainly with the product **Why this works:** * Glossy card stock has no texture or porosity to interfere * It rules out sanding dust, leftover cleaners, or surface oils * It's a fast, low-commitment test that avoids wasting material or time ### Prevention Protocol Moving forward, whenever you experience fisheye or cratering, it's best to **test the topcoat using glossy card stock before proceeding with additional primers**, such as BIN. This simple test can save hours of unnecessary troubleshooting. ### Visual Reference

Figure 1. The image shows clean, circular dimples with smooth edges—hallmarks of internal expulsion rather than random contamination from dust, oil, or surface preparation issues.

### Takeaway > When in doubt, isolate the product from the surface. Fisheyes aren't always related to surface contamination. ### Industry Note This type of internal imbalance is often invisible in spec sheets or early production batches. Common causes include: * Changes in raw material sources * Overzealous defoamer use to correct other issues (foaming, leveling) * Poor quality control in batch blending The defect may not appear until specific environmental conditions or application methods trigger the imbalance.