What Causes Fisheyes When Spraying Bathtub or Tile Coatings and How Do I Prevent It?

There are a handful of finish defects that stop a refinishing job cold and make you question everything you just did. Fisheyes are near the top of that list. You pull the trigger, the coating hits the surface, and instead of flowing out into a smooth, uniform film, it craters. Small circular voids appear — some tight and sharp-edged, some spreading outward in rings — and the surface that was clean and prepped thirty minutes ago suddenly looks like the surface of a golf ball.

The frustrating part is that fisheyes aren't random. They have specific causes, and once you understand what drives them, they become largely preventable. This guide covers what fisheyes are, why they happen in tub and tile refinishing specifically, how to spot the early signs before the whole coat is affected, and how to recover when they do appear.

What Are Fisheyes in Spray Coating?

Fisheyes — also called craters, crawling, or dewetting in technical coating literature — are circular depressions or voids in a wet coating film where the coating has pulled away from a localized area of the surface. The coating doesn't adhere or spread across that spot the way it should; instead it retracts, leaving a circular opening that can range from tiny pinholes to voids a half-inch across.

The physics behind a fisheye is surface tension. Coatings flow and level because the surface tension of the wet film is uniform — the coating spreads evenly across the substrate it's wetting. When there's a low-surface-tension contaminant on the substrate — an oil, a silicone, a wax residue — that spot has lower surface energy than the surrounding area. The coating film, driven by surface tension dynamics, flows away from the low-energy spot rather than across it. The result is a circular void where the coating refused to wet the substrate.



That's the mechanism. The cause is contamination. Always.

Why Fisheyes Are Particularly Common in Bathroom Refinishing

Bathrooms are contaminated environments. The surfaces being refinished are surrounded by — and have been in regular contact with — products that are among the most potent fisheye triggers in spray coating work.

Silicone is everywhere in bathroom environments. It's the primary ingredient in caulks, sealants, and countless shower and bath cleaners. It's also in hair conditioners, body washes, shampoos, and the "shine" products people apply to tubs and tile to make them look clean. Silicone in any form on a refinishing substrate is a near-guaranteed fisheye source. Even trace amounts — the kind left by a cleaning product that seemed like it was rinsed off — can crater a coat.

Body oils, cosmetic products, and residual bath oils also lower the surface energy of the substrate in the spots where they're present. So does wax and polish — products homeowners sometimes apply to fiberglass or acrylic tubs to restore shine that leave an invisible residue no amount of scrubbing with household cleaners removes.



And then there's the bathroom air. The aerosol environment of a bathroom where someone sprays hairspray, deodorant, or air freshener regularly creates a fine coating of silicone and other low-surface-tension compounds on virtually every surface in the room, including vertical tile walls and the ceiling above the tub. Those deposits are invisible. They don't wipe off with a damp cloth. And they're extremely effective at triggering fisheyes.

What Fisheyes Look Like — and How to Spot Them Early

Fisheyes appear as soon as the wet coating film tries to spread across a contaminated spot. They're usually visible within the first few seconds to a minute after a spray pass, while the coating is still wet. Early signs:

• Small circular craters appearing in the wet film, varying in size but consistent in shape
• "Rings" in the coating where the film has thinned at the edges of a contaminated area
• Coating that looks like it's pulling away from certain spots or failing to wet the surface uniformly
• On a second or subsequent coat, voids that follow the same pattern as underlying contamination that wasn't fully removed

The distribution of fisheyes tells you something about the cause. Fisheyes scattered randomly across the entire surface suggest airborne contamination or a widespread surface residue. Fisheyes concentrated in specific areas — near the faucet, around the drain, along the bottom edge — suggest a localized contamination source like a cleaning product residue that wasn't fully removed. Fisheyes in a pattern that follows your spray passes may suggest equipment contamination — oil from the air line getting into the spray stream.



If you see fisheyes forming in the first pass, stop. Continuing to spray over an active fisheye situation adds more material over contamination that's still present, making the problem worse and the eventual repair harder.

The Primary Causes of Fisheyes in Tub and Tile Refinishing

Silicone Contamination

Silicone is the most common fisheye trigger in bathroom refinishing, and it's the most difficult to fully remove. It doesn't dissolve in water. It doesn't respond well to most household degreasers. It can be invisibly present on a surface that looks and feels clean after a thorough wipe-down.

Sources of silicone on refinishing substrates:

• Old caulk residue — even after caulk is removed, silicone from the body of the caulk can migrate into the surface or adjacent areas during the years it was in contact. The visible caulk is gone; the silicone isn't necessarily.
• Shower and bath sprays — products marketed as daily shower cleaners or tile shine sprays almost universally contain silicone. Regular use means the entire surface has received repeated silicone applications over time.
• Hair and body products — conditioners, moisturizers, and leave-in styling products contain silicone compounds that deposit on tub and tile surfaces during normal use.
• Silicone-based cleaning sprays — products that leave a "protective" shine on surfaces, often used in the same cleaning routine as tile scrubbers.
  

Body Oils, Wax, and Polish Residue

Airborne Contaminants

In a recently occupied bathroom, the air itself carries contamination. Aerosol products — hairspray, dry shampoo, air fresheners, body sprays — contain solvents, silicones, and other ingredients that settle on surfaces as an invisible film. Cooking oils can travel through shared ventilation in apartments. Even the oils in the ambient air of a regularly used bathroom deposit on surfaces over time.



If you're working in a bathroom where the client used hairspray that morning or sprayed air freshener the night before, those residues are on the tile, the tub, and every surface in the room, regardless of how clean it looks.

Equipment Contamination: Oil in the Air Line

This is the cause that catches contractors off guard because it looks like surface contamination but isn't. When moisture and oil from a compressor get past an inadequate or worn separator and into the air line, they travel to the gun and get introduced into the spray stream. The result is oil droplets depositing on the surface as you spray — fisheyes that follow your spray pattern rather than correlating with surface areas you know were contaminated.



If fisheyes are appearing in a consistent pattern that tracks with your spray passes — evenly distributed, appearing equally on areas you prepped carefully and areas adjacent to fixtures — suspect the air supply. Check your water/oil separator, drain the compressor tank, and inspect your air hose for any contamination. A compressor without an adequate separator or with an overdue separator replacement is a recurring fisheye source.

Contaminated Spray Equipment

A gun that wasn't fully cleaned after a previous job, or one that has old coating, oil, or cleaner residue in the fluid passages, can introduce contamination into the spray stream. Silicone-based gun lubricants applied anywhere near the fluid passages are a particular risk. Guns should be cleaned thoroughly after every use and should never have lubricants applied to components that contact the coating material.

Masking Tape Adhesive

Some masking tapes, when removed or when the adhesive migrates, can deposit a low-surface-tension residue at the tape edge or on the substrate. This is most likely to affect the perimeter of the spray area — the areas immediately adjacent to where tape was applied. Fisheyes concentrated along tape lines after a coat goes on can indicate adhesive transfer from the masking material.

How to Prevent Fisheyes: A System, Not a Single Step

Preventing fisheyes in bathroom refinishing isn't a single product or a single step — it's a system of practices that collectively minimize the chance of contamination reaching the substrate when the coating goes on.

Step 1: Clean Aggressively and in the Right Sequence

The cleaning sequence matters as much as the cleaning products used. Here's the approach:

1. Remove all traces of silicone — use a dedicated silicone remover or solvent that specifically attacks silicone deposits before any other cleaning step. If the tub or tile has a history of silicone-based cleaner use or if caulk removal was part of the job, this step is critical.
2. Degrease thoroughly — follow silicone removal with a degreasing step to address body oils, wax, and petroleum-based residues. A solvent-based degreaser applied with a clean cloth, wiped in one direction (not back and forth, which redistributes contamination), covers the substrate.
3. Rinse, dry, and wipe — a final solvent wipe with a fresh cloth after degreasing removes any remaining residue and leaves the surface ready for etch or prep. This is the step most often rushed when a job is moving fast.
4. Don't touch the surface with bare hands after the final wipe — skin oils contaminate surfaces immediately and can be enough to trigger a small fisheye in the finished coat.

For Zen-Tek's full prep sequence for porcelain, enamel or ceramic substrates, including cleaning and etching steps, see the post on surface prep and coating steps for refinishing fiberglass tubs and showers.

Step 2: Use AdvanEtch for Surface Profile

After cleaning, AdvanEtch — Zen-Tek's zero-VOC micro-etching sanding liquid — prepares the surface profile that primers need to bond to. The etching process also addresses some residual surface contamination that cleaning alone doesn't fully remove, creating a mechanically clean surface for primer adhesion. It doesn't replace degreasing, but it reinforces the prep by working the surface at a microscopic level.

Step 3: Prime With a Quality Bonding Primer

A high-build bonding primer applied over a properly prepared surface creates a uniform, sealed substrate for the topcoat. Primer fills micro-contamination at the surface level and provides a clean, uniform platform for the topcoat to flow across. Prime-X, Zen-Tek's single-coat epoxy primer, is formulated for strong adhesion to porcelain, fiberglass, acrylic, and ceramic — the substrates where fisheyes are most commonly a concern.

For low-VOC jobs or water-based systems, WTR-Prime provides the same adhesion-focused priming performance without solvent odor.

Step 4: Maintain a Clean Air Supply

Install and regularly maintain a water/oil separator on your compressor line. Drain the compressor tank before starting jobs to remove accumulated moisture. Replace separator elements on schedule. If you're running long air hoses, consider a second separator point closer to the gun. Oil in the air line is an equipment maintenance problem, and it's entirely preventable with a regular maintenance routine. For a full equipment maintenance reference, the Professional Refinisher's Equipment Cheatsheet on the Zen-Tek blog covers compressor setup, separator selection, and air hose considerations.

Step 5: Control the Environment Before Spraying

Before spraying any coating, consider what the bathroom environment has been exposed to in the last 24 hours. If the client used the bathroom that morning and the air still carries hairspray or aerosol product, that contamination is on the surfaces you just cleaned. When possible, ventilate the space thoroughly before prepping — open windows, run the bathroom exhaust fan — to clear airborne contamination from the room before you begin. Once the surface is cleaned and prepped, keep the spray area free of aerosols, sprays, and anyone who might introduce contamination before the coating goes on.

How to Fix Fisheyes When They Happen

Despite best preparation, fisheyes can still appear. How you respond depends on when you catch them and how severe they are.

Catching Fisheyes Mid-Job

If you see fisheyes forming during or immediately after the first spray pass:

1. Stop spraying immediately. Adding more coats over contamination already on the surface makes the problem worse and the repair more involved.
2. Allow the coat to dry to the point where you can sand without smearing.
3. Sand the affected area — or the entire coat if the fisheyes are widespread — back to a smooth, uniform surface. Start at 400 grit and work up to remove the defects.
4. Identify and eliminate the contamination source before proceeding. Did the fisheyes follow a pattern that suggests airborne contamination? Equipment oil? A specific area of the substrate? The pattern tells you where to look.
5. Re-clean the surface with the appropriate solvent or degreaser for the contamination type identified. On jobs where significant silicone removal was required — or where you've caught fisheyes mid-job and suspect silicone may still be present on the surface — this is also the point to consider adding a fisheye eliminator additive as a preventive measure. Add approximately 0.5 oz to your already-mixed topcoat batch, remix thoroughly before spraying, and proceed with the recoat. One important note: fisheye eliminator should only be mixed into the topcoat — never into the primer.
6. Reprime if the sanding went through to the substrate, and allow proper dry time before recoating. One thing worth noting: fisheyes rarely show up in the primer coat, even when applied over surfaces with residual contamination — and with Prime-X applied at a good heavy build, they almost never appear at that stage. It's the topcoat where fisheyes typically reveal themselves, even over a primer coat that looks perfectly clean. It's one of those quirks of the refinishing process that catches contractors off guard, but knowing to expect it means you're watching for fisheyes at the topcoat stage rather than assuming a clean primer coat means you're in the clear.
   

Spot Repair vs. Full Recoat

Whether you can spot repair or need to redo the full surface depends on the extent and distribution of the fisheyes. Isolated fisheyes in one or two areas — where a specific contaminant was localized — can often be addressed with spot sanding, re-cleaning, spot priming if needed, and recoating the affected area blending out to the surrounding finish.



Widespread fisheyes across the entire surface indicate a system problem — the contamination was everywhere, not just in one spot. In that case, the whole coat needs to come back, the contamination source identified and eliminated, and the surface recleaned before repriming and recoating. A fisheye that's not fully fixed before the next coat goes on will telegraph through — the void in the underlying coat creates a surface profile that the topcoat follows, producing a visible defect in the finished surface even if the topcoat itself looks smooth in isolation.

Fisheye Eliminator Additives

Fisheye eliminator additives work by raising the surface tension of the coating, allowing the film to wet and flow over low-surface-tension contamination rather than retracting from it. They're a useful tool when used appropriately — primarily as insurance on jobs where contamination risk is elevated (heavily used bathrooms, fixtures with a history of silicone cleaner use) rather than as a substitute for proper cleaning.



The caution with fisheye eliminators is dosage. These additives are silicone-based compounds themselves — they work by introducing a controlled, uniform silicone into the coating that prevents the film from retracting at contaminated spots. Too much additive, and you've introduced your own contamination into the system — excessive fisheye eliminator in a coat can cause adhesion problems in subsequent coats and may affect gloss. Follow the product's dosage guidance precisely. A little goes a long way. And always test the additive level with the specific coating you're using before using it on a client's job.

Fisheyes vs. Other Spray Defects: How to Tell the Difference

Fisheyes can be confused with other finish defects that produce surface texture or voids. Knowing the difference matters for diagnosis and repair.

Fisheyes Vs. Pinholes

Pinholes are small voids caused by outgassing — air or solvent vapor escaping from the substrate or the coating film during cure. They're typically smaller than fisheyes, lack the circular ring pattern, and are distributed differently (often more random, sometimes concentrated in areas with heavier film build). Fisheyes have a characteristic ring or crater shape from the film pulling away.

Fisheyes Vs. Orange Peel

Orange peel is a uniform surface texture — the coating didn't level properly across the whole surface, not just at contaminated spots. Fisheyes are localized circular defects. If the entire surface has texture, you're looking at orange peel from spray technique or environmental issues, not fisheyes. Zen-Tek's post on what causes orange peel and how to fix it covers that defect in detail.

Fisheyes Vs. Dry Spray

Dry spray is a texture caused by overspray that partially flashes before reaching the surface, depositing as semi-cured particles rather than wet film. It's a grainy, rough texture — not circular craters.

Fisheyes Vs. Adhesion Failure

Adhesion failure produces lifting, peeling, or delamination of the coating — not craters in a wet film. If you're seeing coating lift after cure, that's an adhesion problem, not a fisheye situation.

Choosing Coatings That Minimize Fisheye Risk

Not all coatings carry equal fisheye risk. Well-formulated professional refinishing coatings are engineered with surface tension characteristics that resist fisheye formation in normal contamination conditions — they give you some margin before a marginal cleaning job becomes a visually obvious defect.

Zen-Tek's topcoat systems — Synergy for solvent-borne applications, Zenix for iso-free 2K finishing, and WTR-Tek for water-based work — are all formulated for the kind of controlled application environment that professional refinishing contractors create. They're not immune to fisheyes from significant contamination, but their formulation characteristics support proper wetting and film formation in a correctly prepared substrate.

Water-based coatings like WTR-Tek have a different surface tension profile than solvent-borne systems and can respond differently to the same contamination sources. In some cases, water-based coatings are less sensitive to silicone contamination than solvent-borne systems. In others, water contamination on a substrate that looks dry can introduce a different type of surface defect. The prep principles remain the same regardless of coating chemistry.

Frequently Asked Questions About Fisheyes in Refinishing