Repairing boat gelcoat spider cracks

What are gelcoat spider cracks?

Spider cracks are small cracks in the gelcoat. These hairline cracks often occur naturally due to the aging of the paint system. By repairing gelcoat spider cracks with IJmopox ZF Primer, the treated surface looks great again.

Repair gelcoat spider cracks [manual]

Supplies

• IJmopox ZF Primer
• Thinner for ZF Primer
• Variopox Epoxy Filler
• Double Coat Degreaser
• Sanding paper grit 180, 200 (for dry sanding)
• Nitrile gloves
• Paint trays
• Mixing cups
• Mixing spatulas
• Digital scale
• Velour roller + Paint roller frame
• Filler applicators

Step 1. Cleaning

Before repairing hairline cracks in the gelcoat, it is important to clean the gelcoat. For this, use a high-pressure cleaner or Riwax RS Boat Clean. By cleaning the surface properly, you will clean the cracks well and spray away loose pieces of gelcoat easily.

Step 2. Sanding

Sand the entire surface with 180-grit sandpaper. By sanding the surface, you improve the adhesion between the gelcoat and the ZF Primer that you will apply. After sanding, degrease the surface with Double Coat degreaser.

Step 3. Repairing loose pieces of gelcoat

During sanding, spots may have appeared where the gelcoat has come loose. Touch up these areas with Variopox Epoxy Filler and then sand again. 

Step 4. Applying IJmopox ZF Primer 

We are going to repair the gelcoat crackle with IJmopox ZF Primer. Before using ZF Primer, read the technical data sheet carefully. It contains important information about mixing ratio, amount of thinner, consumption and application.

Instructions for use of ZF Primer

• Determine the desired quantity and weigh both components on a digital scale according to the mixing ratio 87:13.
• Mix the base and hardener well.
• Apply ZF Primer with a velour roller.
• Immediately smooth the surface without pressing hard and rub the layer into the crack with a filler applicator.

We recommend applying 2 coats of this epoxy primer. 1 layer without thinner and then 1 layer with thinner. When working with ZF Primer, always wear covering clothing and nitrile gloves.

Step 5. Follow-up

When you have applied ZF Primer, the tiny cracks that cause gelcoat spider cracks will have been filled. We recommend sanding the surface again with very fine 200 grit sandpaper (dry). After this, you can continue with step 4 of the painting instructions for your deck or hull.

More information about repairing hairline cracks in gelcoat?

Do you have any questions about a gelcoat repair or about repairing crackle? Feel free to contact one of our specialists. We will be happy to advise you to make your project a success. Send us a WhatsApp message or email to support@polyestershoppen.com for free, no-obligation advice.