How To Fix Hairline Cracks On Fiberglass Tubs? A Quick Guide

Fiberglass is renowned for its longevity compared to plastics and ceramics. That is why it is widely used as the core material for bathtubs. But no matter how strong it is, if they are not adequately maintained hairline cracks will most likely emerge. It can be a real hassle to fix hairline cracks on fiberglass tubs.

No need to worry! Hairline cracks on fiberglass tubs can be easily repaired at home. Fiberglass is a versatile product which is comparatively easy to fix than other construction materials.

The Benefits Of A Fiberglass Tub

Down below are some benefits of using a fiberglass tub which you should know about.

  • Fiberglass tubs are famous because they are very lightweight which makes it easier to install.
  • If you want unique shapes and added features like jet, armrest, headrest, drink holder then fiberglass tub should be your first choice. These features can be combined with other materials too, but that will require extra work and extra money.
  • Fiberglass tubs are available in a variety of price range starting from 200 dollars. So you can choose a suitable one according to your budget.
  • These tubs are modern and versatile. You will have plenty of options available to buy from. The maintenance is also cheaper and more accessible than other materials.

Is It Common For A Fiberglass Tub To Crack?

Fiberglass is a kind of fortified plastic, bearing many of the same properties of a plastic. The fiberglass tub is famous for its lightweight and easy installation. It is not prone to damages, and even if it happens most of the flaws are easy to repair at home.

But yes the minor damages are still a factor that ought to be kept in consideration. It is very common for a fiberglass tub to crack because of its porous nature. Upon stressing it by continuously imposing heavy weights and water penetration, hairline cracks form on the surface of the tub.

Such breaks are not severe and can be repaired easily using fiberglass repairing kit.

The Reasons For Hairline Cracks on Fiberglass Tubs

Hairline cracks seem very negligible because of its thin hair-like appearance. But if not treated promptly, the damage can get severe. A hairline crack can appear for various reasons.

The most common reason for a fiberglass tub to crack is weight and pressure. Fiberglass is porous by nature. So continuous exposure to water pairing with the weight problem eventually will weaken the material and cause a hairline crack.

Another responsible factor for this problem is bleach. If bleach or any other chemical application rate is higher than usual, it also causes a hairline crack. Accidental crack can also occur if any heavy object falls on the surface. The durability depends on the user’s carefulness as well.

Purchasing Suitable Kit To Fix Hairline Cracks on Fiberglass Tubs

Before buying the repair kit, you have to ensure the material of your tub. There are different repair kits available based on the material. If you are intended to fix your fiberglass tub, you have to choose the package accordingly.

  • Make sure the tub is made of fiberglass before you start repairing. You can test that easily; merely tap the surface with your knuckle, wooden spoon or any other material which will not be heavy on the tub. If it is fiberglass, it will produce a hollow, non-metallic sound. The surface will also feel very flexible.
  • Select the closest matching color for the kit you intend to buy. It is comparatively easier to match the standard colors like white, almond, off white. Most of the packages come with a tinting product which can be mixed to get the desired color.
  • Purchasing tools separately can be costlier and time-consuming. Better to look for the kits which come as a package and includes all the necessary tools such as sandpaper, fiberglass cloth, paintbrush, mixing container, stirring utensil, protective gloves, etc.

Cracks on Fiberglass Tubs – Hairline Crack Sealers and Repair Kits

Hairline Crack Sealer by GetSet2Save

Hairline Crack Sealer by GetSet2Save
  • INSTANTLY FILL IN CRACKS! - Fix hairline cracks the easy way with EZR Hairline Crack Sealer! Dont spend hundreds of dollars on plumbersfix those mystery leaks the easy way! Works on sidewalks, stairs, floors, walls. Crack filler is super strong and easy to use.
  • SUPER THIN, SUPER FAST, & SUPER EASY! - Sun-resistant formula is quick and easy to apply and dries fast and clear. Super-thin formula flows into the tiniest crevices, allowing it to seek out the source of cracks and seal them all the way up.

This little guy will instantly take care of the cracks! With EZR Hairline Crack Sealer you will be able to fix hairline cracks the easy way. You don’t have to spend hundreds of dollars on plumbers to fix those mystery leaks. You can do it yourself with this instant sealer which is much more cheaper and comfortable to use. Works on sidewalks, stairs, floors, walls. Crack filler is super strong and easy to use.

This hairline crack sealer was designed to be super thin, super fast and super easy to use. The sun resistant formula is quick and easy to apply and dries fast leaving a clear, non noticeable finish. Super-thin formula flows into the tiniest crevices, allowing it to seek out the source of cracks and seal them all the way up. The thinness of the sealer is important because it doesn’t leave behind any bulges or scars. It is precise and comfortable to navigate into the cracks. 

The sealer leaves behind a clear seal which looks just like how a brand new hairline looked when you first purchased it. This penetrating water based sealant is formulated to be so thin that it finds its way inside fine cracks by capillary action and sets to a clear flexible seal.

Applicability is of a wide range as well.

It can be applied and used with multiple surfaces. Works perfect for cracks in drywalls, concrete, sidewalks, stairs, floors, walls, flower pots, window sills, porcelain, driveway, asphalt and more. Perfect for all those cracks around the house that need a fixer upper.

It is manufactured in the USA. Another good feature is that it is safe to use. Made with no harsh chemicals inside the formula it will not irritate your skin if you get it on your hands. However, we advice you keep it away from animals and children, just in case.

MagicEzy Hairline Cracks Fix – (Snow White) – Gelcoat Repair Kit 

MagicEzy Hairline Fix - (Snow White) - Gelcoat Repair Kit - Fix Cracks and Scratches Like a Pro - Fiberglass Boat Repair Kit - Boats, Jet Skis, Fiberglass, PVC, Carbon Fiber, Plastic
  • EXPERT CRACK AND SCRATCH REPAIR: Fix fine damage easily. Works on hairline cracks, stress cracks, spider cracks and scratches.
  • GELCOAT REPAIR KIT IN A TUBE:  One-part, colored, glossy fiberglass gelcoat repair filler and sealant so it colors, fills and seals in one application.

Fiberglass Chip Repair in a Tube is a one-stop shop for all of your fiberglass chip repair needs. Hairline Fix is a quick and effective solution to repair small cracks and scratches in boat gelcoat. It’s a gleaming, all-in-one gelcoat repair filler that can make repairs in seconds.

It contains gelcoat paint, filler, and sealer all in one bottle. It is not necessary to combine multi-part epoxy solutions. There’s also no need to sand or polish the surface. You only need to simply clean the are that needs to be fixed, apply the sealer, level it and wipe it. That’s all there is to it.

Ideal for Holes, Gouges, and Deep Chips. If you have more severe damage, use our 9Second Chip Fix solution. MagicEzy’s ‘deep damage’ solution for practically any surface is 9 Second Chip Fix.

Simply prepare the surface with MagicEzy MegaFusion before applying MagicEzy MegaFusion to plastic-like surfaces such as acrylic, PVS, and carbon fiber. This will help to reinforce the region and keep the repair from peeling or bursting out.

Use it on Most Surfaces

  • Fiberglass Boats
  • Jet Skis
  • Ceramic Tiles
  • Marble and Granite
  • Countertops
  • Acrylic Baths
  • Fiberglass shower bases
  • Wall touch-ups

Colors can be mixed and matched. Customers have noticed that Snow White goes well with most white boats, but if you’re not sure, try mixing it with another of our hues for a better fit. You have to keep in mind that combining the product with any colorants will diminish the filler’s adhesion level.

This repair kit job once done will surely last a lifetime. The manufacturers claim to provide a Lifetime Durability Protection. The unit incorporates cutting-edge nanotechnology that penetrates deeply into the pores to provide structural grade adhesion and long-lasting healing. The formula also bends with your boat, preventing cracking or falling out. The manufacturers are sure of it that they guarantee it for life. If the repair fails, they will send you a replacement tube at no cost.


  • Penetrates deeply into the pores of the damage
  • Industrial grade adhesion. Lifetime durability protection.
  • One part, colored filler. No messy mixing or fumes.
  • Built-in levelling device for smooth repairs. Repairs last for at least 3 years.
  • Water resistant. Above the waterline use only
  • Flexes with your boat so repairs won’t pop out.
  • Suitable for fine cracks and scratches
  • Handy, pocket-sized .43oz tube

Tub, Tile, Hairline Cracks and Shower Repair Kit (Color Match)

Tub, Tile and Shower Repair Kit (Color Match), 3.7oz Fiberglass Repair Kit, Porcelain Repair Kit White/Almond/Black/Bone/Bisque/Biscuit/Grey/Cream/Off White/Beige, Odorless Bathtub Paint
  • FIBERGLASS REPAIR KIT - Repairs chips, scratches, dents, worns and holes . Works on fiberglass, acrylic, ceramic, porcelain, gel-coat, enamelled steel and enamelled cast iron .
  • PEFECT COLOR MATCH - Matchs for white, arctic, milk white , dune, biscuit,bisque, almond, linen, bone, sandbar, ice gray, cashmere, thunder grey and black . Our product Repaired without trace. You don't needs to add other paint on the surface

This is Amazon’s number one repair kit currently. Fiberglass repair kitrepairs chips, scratches, dents, worns and holes . Works on fiberglass, acrylic, ceramic, porcelain, gel-coat, enamelled steel and enamelled cast iron .

Perfect color match is its main advantage and the reason why the product is a best seller. Obviously, once your hairline is cracked you don’t want it to be concealed with something that doesn’t look like the original material. To match the color perfectly you need the right repair kit that comes with the variety of colors and shades. This one matches for white, arctic, milk white, dune, biscuit, bisque, almond, linen, bone, sandbar, ice gray, cashmere, thunder grey and black .

Because of such wide range of colors the product leaves no trace on the hairline or any other surface that it is applied to. You don’t needs to add other paint on the surface. Saves money and time.

Another very important feature is that it is completely non toxic and has no odor. This fiberglass repair kit use nanotechnology, no harsh or strong chemicals that can irritate or damage your skin and body. Completely safe to use around children and pets in case you leave it behind.

The manufacturers provides great adhesion in a few simple steps. It comes with a five years of the durability guaranteed. The product is water resistant and stop leaks immediately. In addition, if a particular unit comes damaged or you have any other problems, they offer a 60 day full refund guarantee. If you are not satisfied with the the products even after its use you can return it for a full refund within 60 days.

Package Includes:

  • 2 Dyes – Black gel *1 , Yellow gel *1.
  • A Group *1 ,B Group *1
  • Scraper *1
  • Wood Stick*1
  • Disposable Gloves*2
  • Toothpick*2
  • Sand Paper*2


1.The original color of the product is arctic white

2.You have to use the tiniest speck of color gel to match your color desire (smaller than the tip of a tooth pick)

3.Next, use Brown color gel to match Brown series

4.And use Black color gel to match Grey series


It can be used with rusty tub and sinks, missing chunk of porcelain or chips on your bathtub and sink, cracks on shower stall tiles, worns and holes on toilets.

Saves tons of money instead expensive professional repairs.  The color of the product is exactly the same as the bathtub you are going to repair. Strong repair, up to 5 years. The job is done extremely quickly as the surface can be repaired in 10 minutes. Safe for children and pets.

Questions you may care about: 

Q: can this product matches for my bathtub?

A: the products can fit most of the toilets, bathtubs, tiles on the market, it is a really good color match .

Q: How large of a crack can this repair?

A: Product parameters (diameter=2inch, height=0.4inch), and there are also 2 bottles (Part A and Part B)

Tips to avoid sanding and keep glossiness ?

After using the mixture to patch the surface, you can use clear tape to cover the surface, then make sure the surface is smooth. When the mixture is dry, remove the clear tape.

MagicEzy Tile RepairEzy – White Ceramic Tile Repair Filler to Fix Tile Chips and Hairline Cracks

MagicEzy Tile RepairEzy (White) - Ceramic Tile Repair Filler to Fix Tile Chips and Cracks - Super Strong Adhesion - Ceramic, Porcelain, Acrylic, Fiberglass, Enamel
  • Versatile Ceramic Tile Repair Kit – it’s not only great for porcelain tile repair, also use it for granite countertop repair, ceramic sink repair, acrylic bathtub repair, fiberglass shower, porcelain dinnerware.
  • Virtually Invisible Crack Repair For Most Tile Damage - fix tile cracks, chipped tiles, tile holes, pitted granite – you name it. It’s also a tile scratch remover and hides vinyl floor scratches. Or use it as a wall touch up paint for gouges Use it on cracks up to 1mm. For deep damage use our Deep Chip Filler. Scroll down for more information.

MagicEzy Tile Repairezy is a ground-breaking epoxy tile filler that repairs most forms of surface damage on tiles and many other surfaces in your house. It may be used to patch up pitted tiles, chipped porcelain, scuff marks, gouges, broad fissures, and tiny sections of broken grout.

It contains a filler, sealer, and gloss tile touch up paint in one container, eliminating the need to prepare multi-part solutions.

Even better, unlike paint pens or stiff tile fillers, the revolutionary formula’s nanoparticles penetrate deeply into the pores of the tile damage for extremely strong adherence. In fact, the repairs are so tough that they are permanent. As a result, the manufacturer provides a Lifetime Durability Protection.

It’s also super simple to use. It is not necessary to sand or polish the tile beforehand. Simply wipe the area and spray the substance into the chipped or broken tile. Then, level the surface and wipe away any streaks. It will have a shiny sheen when it dries. You may simply tone down the gloss levels of matte tiles to match the shine of the surrounding tile. There are detailed instructions included.

You may purchase a single color-matched tube or mix & match with one of our Tile Repair Kits. Simply follow the MagicEzy Hue System directions inside the packet to match almost any color.

Specific colors are listed below:

  1. The Terracotta Repair Kit – for earthy terracotta tiles
  2. The Primary Colors Kit – for bright or federation colored tiles
  3. The Neutrals Tile Repair Kit – for a large range of beige, almond, tan, browns, and creams
  4. The Beige/White Kit
  5. The Honey Beige/White Kit
  6. The Black and White Kit – for different shades of gray.
  7. The Beige Kit -Chocolate, White, and Honey-Beige
  8. The Gray/White Kit

Features of the product:

The sheen may be changed from high gloss to matte.
Lifetime Durability Protection backs up permanent fixes. If the repair is ever unsuccessful, we will send a replacement tube.
It is water soluble.
Water repellent.
It is suitable for use on vertical surfaces.
All-in-one filler, colorant, and sealer.

Works on: ceramic or porcelain tiles, granite, marble and stone tiles or countertops, gelcoat and fiberglass, wood, fiberglass, acrylic.

Can be used on:

  • Bathroom tiles
  • Kitchen tiles
  • Kitchen Countertops
  • Bathroom Vanities
  • Suitable for both floor and wall tiles
  • Bathtubs
  • Showers
  • Benchtops

NADAMOO Tub Repair Kit for hairline cracks 

NADAMOO Tub Repair Kit White Tile Shower Repair Kit for Fiberglass Porcelain Ceramic Acrylic Stone, Fix Crack Chip Scrap Hole - 3.5 Oz
  • Use to repair chips, scratches, dents, cracks, worns and holes for any porcelain ceramic surface like tub, tile, shower, bathtub, vanities, sink. Also work on fiberglass, stone.
  • All of our mixture are permanent repairs and stronger than the original stone.

The package includes all of the essential repair tools, such as gloves, a spatula, masking tape, sandpaper, compound part A, and compound part A. Combine compound Part A with compound Part B, then apply the mixture to the injured region. It will fill up the tiny pits and scrapes and remove surface imperfections, restoring the tub to fresh and smooth condition. In 12-24 hours, this combination dries to a firm finish. When dry, it suits most white surfaces and gives the surface a glossy luster.

Repair kit may be used on all varieties of porcelain tubs, as well as fiberglass and cultured marble tubs. It may be used on a range of porcelain surfaces, including ceramic tiles, sinks, and showers, as well as tubs. With its high adherence and stickiness, the combination may also be used as an adhesive for component joints in wood, acrylic, ceramics, porcelain, and stone.


  • All of the mixtures are long-lasting restorations that are stronger than the original stone.
  • DIY repairs may be completed in a few easy steps: all you have to do is combine repair compound parts A and B, apply them to the damaged area, and smooth the surface.
  • When dry, the surface takes on a porcelain-like look.
  • The kit includes: compound part A (50g/1.7oz) + compound part B (50g/1.7oz) + glove x 2 + sandpaper x 2 + spatula x 2 + transparent masking tape x 3.

Hairline Cracks on Fiberglass Tubs

Want to know how to fix the hair line crack? Down below is everything you need to know about the process.

Tools you will need include:

  • Household cleaner
  • Rag or sponge
  • Sandpaper
  • Fiberglass repair kit
  • Paint brush
  • Scissors
  • Fiberglass cloth

The Process of Fixing Hairline Cracks on Fiberglass Tubs

Follow this process step by step to have a smooth repairing session.

Step 1

Apply your preferred household cleaner on a rug or sponge and clean the damaged area. It is a must to make sure that no stain or dust is left behind. Otherwise, adhesives won’t stick properly. Wipe the wet area and let it dry.

Step 2

Sand the area around the cracked line lightly using sandpaper. Brush away the dust.

Step 3

Paint the crack line with the fiberglass adhesive using the brush that comes with the kit. A small paintbrush can also be used. Try to cover the inside of the crack and also adjacent 1 inch to the damaged area. Allow the adhesive to dry completely.

Step 4

When it’s dry, fill the crack with a fiberglass filler using a putty knife. If there is any excess filler coming out of the crack line, scrap it away using the same knife. Let it dry once again.

Step 5

Sand the patched area using sandpaper. Keep sanding until the level of the repaired part matches the surface of the rest of the tub. Brush away the sanding dust.

Step 6

Mix the epoxy gel that comes with the repair kit and paint it on the affected surface using a paintbrush. Apply it on the adjacent surface as well. Then cut a fiberglass cloth according to the size of the painted area and press the fabric on it gently with your hand.

Make sure that it has been placed smoothly and no air bubble has been introduced. Then apply the second coat of epoxy gel on it.

Step 7

In the last step apply the sealer or finish coating that comes with the kit. Brush it on the repaired area and let it dry.

So by following the above mentioned 7 steps, hairline cracks on fiberglass tub can be easily fixed at home with a minimum cost. The fiberglass repair kit is widely available in any hardware shop.

Hairline Cracks – Struggles with Mismatched Patch

It is a sad truth that in most of the cases your repaired area will not precisely match with the rest of the surface. Even if you gain expertise, still it’s not possible to make it look completely like before. The main struggle is to match the original color of the tub.

However, if you are too worried about it, you can directly contact the manufacturer of your tub. If you know the brand, then it is not difficult to reach them online. Some of the brands supply one extra can of the same color upon request.


Fiberglass tub serves as a cost-friendly and durable alternative to traditional metal and ceramic tubs. Tubs with too little base support or subject to hulking use might develop cracks over time.

If left unaddressed, the hairline cracks can spread to the side and floor of the tub and ultimately damage the whole tub. As mentioned throughout the article, such cracks can be repaired swiftly at home.

The only trick that you can implement is – whenever you see a crack, immediately go for action no matter how big or how small the crack.

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