• My Account
  • My Wish List ()
  • Sign In
  • Compare
  • Create an Account
Toggle Nav
Search
Menu
Account
Awlgrip Application Guide › Surface Preparation › Fiberglass

Fiberglass Surface Preparation for Awlgrip Paint

Before applying Awlgrip primer or topcoat systems, fiberglass and gelcoat surfaces must be properly cleaned, sanded, and prepared. Mold release agents, wax contamination, and oxidation will prevent epoxy primers from bonding correctly.

Need help with a project? Call our coatings team: 321-639-3046

Quick Answer: How Do You Prep Fiberglass for Awlgrip?

  • Clean and degrease — remove mold release agents, wax, and surface contamination
  • Sand fiberglass / gelcoat with 80–120 grit sandpaper (Awlgrip official spec)
  • Remove all sanding dust by brush, vacuum, or compressed air
  • Final clean with the two-cloth solvent wipe method using Awlprep T0008 or Awlprep 400 T0170
  • Apply 545 Epoxy Primer as the finish primer before topcoat
  • For peel-ply composites: apply Hullgard Extra directly after peel-ply removal

Skipping these steps is the most common cause of adhesion failure, fisheyes, or coating delamination in Awlgrip systems.

Fiberglass Prep at a Glance

StageTool / ProductAwlgrip Official Spec
Clean / degreaseDetergent + fresh water rinseRemove salt, dirt, surface contamination
Remove mold releaseAwlprep T0008 or Awlprep Plus T0115Eliminate wax, grease, oil before sanding
Sand fiberglass / gelcoat80–120 grit sandpaperAwlgrip YPAC standard for polyester / gelcoat
Sand peel-ply compositeNone — do not sandApply Hullgard Extra directly after peel-ply removal
Dust removalBrush or vacuum + compressed airSurface visibly clean before solvent wipe
Final solvent wipeT0008 (fast dry) or T0170 (hot weather)Two-cloth method: wet cloth + dry cloth
Finish primerAwlgrip 545 Epoxy Primer (D8001/D1001)Mix 1:1:½ (base:converter:reducer), 2–3 coats, 2–3 mils DFT

Where 545 Sits in the Awlgrip System

545 Epoxy Primer is the final primer applied before any Awlgrip topcoat. It can be applied directly over prepped fiberglass, or over Hullgard Extra, High Build, Ultra Build, or Awlfair LW fairing compound. Per the official Awlgrip system:

  1. Step 1Surface prep — degrease, sand 80–120 grit, two-cloth solvent wipe
  2. Step 2(Optional fairing) — Awlfair LW or Sprayable Fairing Compound, then High Build or Ultra Build over fairing
  3. Step 3Hullgard Extra — if pre-fairing or for additional adhesion (optional on clean fiberglass)
  4. Step 4545 Epoxy Primer — 2–3 coats at 2–3 mils DFT, applied as the final primer
  5. Step 5Topcoat — Awlgrip, Awlcraft 2000, Awlcraft SE, or Awlgrip HDT applied 12+ hours after final 545 coat

For most fiberglass refits, the simplified system is: prep → 545 → topcoat. Add Hullgard Extra and High Build only when fairing or filling is required.

Step-by-Step Fiberglass Preparation

1

Initial Cleaning & Degrease

Remove wax, grease, mold release agents, and salt contamination before sanding. Mold release on new fiberglass can migrate to the surface for weeks after layup — it is the leading cause of fisheyes on new builds.

Wash with detergent + fresh water, then wipe with Awlprep T0008 or Awlprep Plus T0115. Degreasing after sanding only drives contamination deeper into the surface.

2

Two-Cloth Solvent Wipe

Always wipe with two cloths to prevent re-depositing contamination across the surface.

  • Cloth #1 wetted with T0008 or T0170 dissolves contamination
  • Cloth #2 dry, lifts the residue off before solvent flashes

Single-cloth wiping just spreads contamination as the solvent evaporates. Replace cloths often — fold to a clean section every few square feet.

3

Sand Fiberglass / Gelcoat

Sanding creates the mechanical bond required for epoxy primer adhesion. Awlgrip's official YPAC training specifies 80–120 grit sandpaper for polyester, gelcoat, and composite (non-peel-ply) substrates.

  • 80 grit — heavy oxidation, repairs, deep contamination
  • 100–120 grit — standard new-build or refit prep

Block sand whenever possible — orbital-only leaves swirl marks that can telegraph through high-gloss topcoats.

4

Peel-Ply Composites

If the fiberglass was laid up with peel-ply, the official Awlgrip procedure is different:

  • Do not sand — the peel-ply leaves a perfect mechanical profile
  • Apply Hullgard Extra directly after peel-ply removal
  • Continue the system from Hullgard Extra normally

This is the only fiberglass prep that skips sanding.

5

Remove Dust

Dust contamination causes primer pinholes, craters, and adhesion failures.

Brush or vacuum the surface, then use compressed air to clear crevices, then a tack cloth (73009 Deluxe Tack Rags) as the final pass. The surface should appear uniformly dull with no glossy patches.

6

Final Solvent Wipe

Perform one last two-cloth solvent wipe immediately before primer application.

  • T0008 — fast-dry, standard temperatures
  • T0170 (Awlprep 400) — hot weather, 5x slower than T0008; also good for tape residue

The dry wipe cloth should come back clean. If anything shows on it, wipe again before opening the primer can.

7

Apply 545 Epoxy Primer

Mix Awlgrip 545 per the official spec:

  • Mix: 1 base : 1 converter : ½ reducer (spray)
  • WFT/DFT: 7–10 mils wet / 2–3 mils dry
  • Coats: 2–3 coats
  • Recoat itself: 1 hr (spray) / 12–14 hr (brush/roller)
  • Topcoat after: 12 hours minimum

Surface temperature must be at least 5°F above dew point. In cool conditions, add M3066 Cold Cure (545 only).

Pro Tip: If the fiberglass surface still has gloss after sanding, the primer will not adhere properly. The surface should appear evenly dull with a uniform 80–120 grit scratch pattern. Run your hand across the panel — any glossy patches you can feel as smoother need to be sanded again before priming. Awlgrip's YPAC training specifically warns that mold release contamination can cause delamination and topcoat failure even on properly sanded surfaces.
Watch Out — Mold Release Migration: New fiberglass parts can have mold release agents (PVA, silicone, wax) migrate to the surface for weeks or months after layup. Per Awlgrip's official YPAC guidance, mold release residue can cause delamination or contaminate the paint system. Always degrease with T0008 or T0115 before sanding — even on parts that look clean. Sanding through mold release without dewaxing first drives the contamination deeper and is the leading cause of fisheyes on new builds.

Recommended Products for Fiberglass Prep

The complete prep + primer kit for fiberglass substrates, in the order you'll use them. All specs from the official Awlgrip Yacht Application Paint Center training.

Awlprep Surface Cleaner

T0008

Fast-dry clean solvent for the two-cloth method. Use before and after sanding. Lifts latent moisture off the surface.

Shop T0008 →

Awlprep Plus

T0115

Stronger solvent designed to remove wax, grease, and oil. Use before sanding. Will soften partially cured primers — do not use over fresh paint.

Shop T0115 →

Awlprep 400 Hot Weather

T0170

Final wipe-down product similar to T0008 but 5x slower — ideal for Florida summer applications. Also good for removing tape residue.

Shop T0170 →

545 Epoxy Primer

D8001 (white) / D1001 (gray) + D3001 converter

The finish primer before topcoat. 1:1:½ mix, 2–3 coats at 2–3 mils DFT. Spray, brush, or roller.

View 545 Technical Guide →

Hullgard Extra

D6120 base + D3730 converter

Required for peel-ply composite prep. Mix 10 : 1.5 by volume, reduce 5–15%. Recoatable for up to 6 months without sanding.

View Hullgard Guide →

High Build Epoxy Primer

D9002 / D8002 + D3002 converter

Use when fairing scratches or surface imperfections need to be filled before 545 and topcoat.

View High Build Guide →

Cold Cure Accelerator

M3066

For 545 Epoxy Primer only. Improves cure of 545 in cool conditions. Not a substitute for minimum application temperature. Do not use in High Build or Ultra Build.

Shop M3066 →

Deluxe Tack Rags

73009

Low-tack cloth specifically rated for use with Awlgrip. Picks up dust without transferring residue. 4 cloths per pack.

Shop 73009 →

Common Fiberglass Prep Questions

What grit should I sand fiberglass to before applying Awlgrip primer?
Short answer: Per Awlgrip's official YPAC training, sand polyester, gelcoat, and non-peel-ply composite substrates to 80–120 grit. Going finer than 120 reduces mechanical adhesion for epoxy primers like 545.
Long answer: The 80–120 grit profile is what Awlgrip's training program specifies for fiberglass and gelcoat substrates. 80 grit is for heavy oxidation or repair work; 100–120 grit is the standard for typical prep. After 545 cures, sand to 320–400 grit before topcoat application. Block sanding is preferred over orbital-only because orbital sanders leave swirl patterns that can telegraph through high-gloss topcoats.
Where does 545 Epoxy Primer fit in the Awlgrip system?
Short answer: 545 is the final primer applied before any Awlgrip topcoat. It goes on directly over prepped fiberglass, or over Hullgard Extra, High Build, Ultra Build, or Awlfair LW fairing compound.
Long answer: 545 is the universal finish primer in the Awlgrip system. It provides corrosion resistance, adhesion, and a uniform surface for the topcoat to bond to. On clean fiberglass, the simplified system is prep → 545 → topcoat. When fairing is required, the full system is prep → Awlfair LW → High Build → 545 → topcoat. When extra adhesion is needed, Hullgard Extra is used as the substrate primer with 545 on top. The official Awlgrip Anti-Corrosive System on metal substrates is Max Cor CF → Hullgard Extra → 545 (2 coats) → topcoat.
What is the mix ratio for Awlgrip 545 primer?
Short answer: 1 part base (D8001 white or D1001 gray) : 1 part converter (D3001) : ½ part reducer (T0006 standard, T0167 low-VOC, or T0031 brush/roller).
Long answer: The official Awlgrip mix ratio for 545 is 1:1:½ by volume. Apply 2–3 coats at 7–10 mils WFT / 2–3 mils DFT. Spray application recoats itself in 1 hour; brush/roller recoats in 12–14 hours. Pot life is 6–8 hours but 2–3 hours gives best application properties. Topcoat with Awlgrip, Awlcraft 2000, Awlcraft SE, or Awlgrip HDT after 12 hours minimum cure. In cool conditions, add M3066 Cold Cure accelerator (545 only).
Do I need to remove gelcoat before applying Awlgrip?
Short answer: Not unless the gelcoat has failed. Sound, well-bonded gelcoat is an excellent substrate after degrease, 80–120 grit sand, two-cloth wipe, and 545 primer.
Long answer: Awlgrip's official guidance treats gelcoat as a polyester substrate — clean and degrease, remove release agents and waxes, then sand 80–120 grit. Removal is only required when gelcoat is heavily blistered, delaminating from the laminate, or so chalky that you cannot sand back to sound material. See our dedicated gelcoat preparation guide for full details.
How do I prep peel-ply composite for Awlgrip?
Short answer: Apply Hullgard Extra directly after peel-ply removal — do not sand. The peel-ply leaves a perfect mechanical profile already.
Long answer: This is the one fiberglass prep that skips sanding. Per Awlgrip's official YPAC procedure: as soon as the peel-ply is removed, apply Hullgard Extra (D6120 base / D3730 converter, mixed 10:1.5 by volume, reduced 5–15%) directly to the freshly exposed surface. The peel-ply texture provides ideal adhesion. From there, follow the normal Hullgard → 545 → topcoat sequence. Do not let the peel-ply surface get contaminated between removal and Hullgard application.
Why do I need to dewax new fiberglass with T0008 or T0115?
Short answer: New fiberglass surfaces carry mold release agents and silicone that migrate to the surface for weeks or months after layup. Per Awlgrip, mold release contamination can cause delamination and paint system failure.
Long answer: Mold release (PVA, wax, silicone) is intentionally applied to molds so parts release cleanly. That release agent transfers onto the part surface and continues to bloom out for an extended period. If you sand without dewaxing first, the abrasive grinds the contamination into the surface scratches where solvent cleaner cannot reach. The result is fisheyes when primer is applied, even though the surface looked clean. Degrease → sand → T0008/T0170 wipe → prime is the only sequence that reliably eliminates this on new fiberglass.
How long can I wait between sanding and priming fiberglass?
Short answer: Prime within 8 hours of final sanding when possible. Longer delays risk re-contamination from shop dust, humidity, and airborne silicone.
Long answer: Awlgrip's YPAC training calls for priming aluminum within 8 hours of grinding to prevent corrosion. While fiberglass doesn't corrode, the same urgency applies for contamination control. Once a fiberglass surface is sanded and wiped, shop dust settles, humidity can affect the surface, and airborne silicone from nearby buffing or polishing operations can re-contaminate the surface. Best practice is to sand, wipe, and prime in one continuous workflow. If priming must be delayed, cover the prepped surface with kraft paper or plastic and re-wipe with T0008 or T0170 immediately before priming.
Can I apply Awlgrip topcoat directly over fiberglass without primer?
Short answer: No. Awlgrip topcoats must always go over an Awlgrip-compatible primer. On fiberglass, that means 545 Epoxy Primer (and optionally High Build, Ultra Build, or Hullgard Extra below 545) before any topcoat.
Long answer: Awlgrip topcoats are formulated to bond to a primed surface, not raw fiberglass. Per Awlgrip's official system, every yacht-grade topcoat application requires a primer system underneath. Direct topcoat application skips the corrosion protection, adhesion promotion, and surface filling that the primer system provides. The result is poor adhesion, gloss dieback, and finish failure. The minimum system is prep → 545 → topcoat.
How do I prep fiberglass that has minor scratches and gouges?
Short answer: Repair with Awlfair LW epoxy fairing compound, block-sand to a smooth profile, then prime with High Build over the faired area, then 545 across the whole panel before topcoat.
Long answer: Minor scratches and gouges should be filled with Awlfair LW (D8200 base / D7200 standard or D7222 fast converter, mixed 1:1 by volume). Awlgrip's official guidance is that Awlfair LW must be overcoated with High Build or Ultra Build before going to a finish primer — do not apply 545 directly over fairing compound. The full repair system is: fair → block sand 80→120 grit → High Build (or Ultra Build for deeper fills) → sand 320–400 → 545 → topcoat. See our Fairing & Repairs guide for the full procedure.
Where can I buy Awlgrip fiberglass prep products in Florida?
Short answer: Fiberglass Florida stocks the full Awlgrip fiberglass prep system — T0008, T0115, T0170, 545, Hullgard Extra, High Build, Ultra Build, Awlfair LW, M3066 Cold Cure, and 73009 tack rags — and ships statewide from Brevard County.
Long answer: We carry every product mentioned in this guide and can spec a complete fiberglass prep + primer + topcoat package for your project. Browse the Awlgrip catalog, call 321-639-3046, or email orders@fiberglassflorida.com for same-day shipping on in-stock items.

Related Awlgrip Surface Preparation Guides

Need Help Choosing the Right Awlgrip System?

Our marine coatings team can help you select the correct primers, reducers, and application equipment for your fiberglass project.

Call 321-639-3046 or browse our full Awlgrip product line.

Shop Awlgrip Paint Systems