Fisheyes In Clear Coat – How To Prevent And Fix Surface Contamination
Fisheyes are small, crater-like voids in your finish caused by surface contaminants like silicone, oil, or wax repelling the wet paint. You can prevent them by thoroughly cleaning the substrate with a dedicated degreaser and ensuring your compressed air system is free of moisture and oil.
You have spent hours sanding, masking, and prepping your project, only to pull the trigger on your spray gun and watch as the finish crawls away from tiny spots. It is a gut-wrenching moment for any DIYer, whether you are restoring a vintage truck or finishing a custom hardwood tabletop.
That frustrating pattern of small, circular dimples is known as fisheye, and it is the single most common enemy of a glass-like finish. While it feels like a disaster in the moment, you do not have to strip the entire piece down to the bare wood or metal.
In this guide, I will show you exactly why these defects happen and how you can reclaim your project without losing your mind. We will walk through the science of surface tension and the practical steps to ensure your next coat lays down perfectly flat.
Understanding the Causes of Fisheyes in Clear Coat
At the most basic level, a fisheye is a failure of adhesion. The liquid coating is being repelled by a localized spot of contamination on the surface you are trying to cover.
When your clear coat hits a microscopic speck of oil, grease, or silicone, the surface tension of the paint becomes higher than the attraction to that contaminated spot. The paint pulls away, creating a crater that exposes the layer beneath.
The most frequent culprits are usually products we use every day in the shop. Silicone-based furniture polishes are the primary offender, as they are notoriously difficult to remove and can travel through the air to land on your project.
How to Prevent Surface Contamination
Prevention is always cheaper and faster than remediation. If you want to avoid dealing with fisheyes in clear coat, you must treat your workshop like a cleanroom during the final stages of a project.
Start by auditing your cleaning supplies. Never use household glass cleaners or dusting sprays in the same room where you are spraying finishes, as these almost always contain silicone.
Invest in a high-quality wax and grease remover. This solvent is specifically formulated to lift contaminants from the surface without leaving a residue of its own.
- Wipe the surface in one direction using a lint-free cloth.
- Use a second, clean cloth to dry the surface immediately before the solvent evaporates.
- Always wear nitrile gloves, as the oils from your skin are enough to ruin a finish.
The Importance of Air System Maintenance
Even if your project surface is surgically clean, you might still see craters appearing as you spray. This is a classic sign that your compressed air system is the source of the problem.
Air compressors naturally generate moisture and heat, which causes oil from the internal pump to bypass the seals and enter your air lines. If that oil hits your workpiece, you will get instant fisheyes.
To stop this, install a multi-stage air filtration system. A basic water trap at the tank is not enough; you need an oil-coalescing filter positioned as close to your spray gun as possible.
Check your drain valves on the compressor tank daily. If you see milky water coming out, that moisture is likely making its way through your hoses and into your finish.
Addressing Fisheyes in Clear Coat During the Process
If you are already mid-spray and you notice the finish starting to crawl, stop immediately. Do not try to “bury” the fisheyes with more coats, as the contamination will just migrate to the surface of the new layer.
The best approach is to let the clear coat flash off and cure until it is hard enough to sand. Once cured, you can lightly sand the area with 800 to 1000-grit sandpaper to level the craters.
Clean the area again with a fresh solvent wipe. If the contamination was localized, you might be able to spot-repair it. If the entire panel is affected, you may need to use a specialized fisheye eliminator additive.
These additives lower the surface tension of your clear coat, allowing it to flow over the microscopic contaminants rather than pulling away. Use these sparingly, as adding too much can compromise the final hardness and UV resistance of your finish.
Choosing the Right Tools and Materials
Your choice of spray equipment plays a massive role in how your finish settles. HVLP (High Volume, Low Pressure) guns are generally better for preventing defects because they use less air velocity, which reduces the chance of blowing contaminants onto your wet surface.
When selecting a clear coat, look for products that are compatible with your substrate. A high-quality automotive-grade clear coat will often have better leveling properties than cheaper alternatives.
Always perform a test spray on a scrap piece of material if you are using a new brand of finish. This allows you to check for “orange peel” or cratering before you commit to the actual project piece.
Frequently Asked Questions About Fisheyes
Can I just buff out fisheyes after the clear coat dries?
Generally, no. Buffing removes material from the surrounding area, but the fisheye crater usually goes deep into the finish. If you try to buff it flat, you will likely burn through the clear coat before the crater disappears.
Is it possible that my tack cloth is causing the problem?
Yes, it is possible. Some cheap tack cloths contain waxes or oils that can transfer to your project. Only use high-quality, professional-grade tack cloths and use them with a very light touch.
Do I need a fisheye eliminator in every batch of paint?
No, you should never use an additive unless you absolutely have to. They are a “band-aid” for a contamination problem. It is much better to find the source of the oil or silicone and eliminate it than to rely on chemicals to fix your process.
What is the best way to clean a surface before painting?
Use a two-cloth method. Apply a wax and grease remover with the first cloth to dissolve the contaminants, then immediately wipe it dry with a second, clean cloth. If you let the solvent air-dry, you are just moving the dirt around rather than removing it.
Final Thoughts on Achieving a Flawless Finish
Dealing with fisheyes in clear coat is a rite of passage for every garage DIYer. It is frustrating, but it is also a great teacher that forces you to refine your shop hygiene and equipment maintenance.
Remember that a perfect finish is 90% preparation and 10% spraying. If you take the time to clean your workspace, maintain your air lines, and handle your materials with care, you will rarely see these craters again.
Stay patient with your process, keep your tools clean, and do not be afraid to sand back a mistake. That dedication to the craft is what separates a quick fix from a professional-grade result. Now, get back into the shop and finish that project with confidence!
