How to repair a scratched or cracked resin shower tray

What you need

• Torch
• Hairdryer
• Plastic spatula
• Foam sanding blocks
• Microfibre cloths
• Masking tape
• Nitrile gloves and a dust mask
• Safety glasses
• Wet and dry sandpaper in 400, 800, 1200 and 2000 grit
• Gelcoat repair kit or white resin filler (Leroy Merlin, Bricodepot)
• Degreaser or isopropyl alcohol
• Polishing compound for car bodywork or sanitaryware
• Anti-mould sanitary silicone to finish the perimeter

Step by step

1. 1

   Assess the damage

   Dry the tray and shine the torch flat across it. Run a fingernail over each scratch. If it does not catch, it is only on the surface. If it goes right through the tray or the tray gives underfoot, stop here: it has to be replaced.

2. 2

   Clean and degrease

   Wash the tray with water and neutral soap, rinse and wipe with a cloth soaked in isopropyl alcohol. Leave it to dry for at least an hour, using a hairdryer on a low setting. The filler will not bond to soap or damp.

3. 3

   Protect the surrounding area

   Use masking tape to mark out a rectangle around the repair, about 2 cm away. That way you only sand what you need to and do not dull the shine of the whole tray.

4. 4

   Open up the crack or chip slightly

   With a craft knife, scrape the edges of a fine crack into a gentle V of 1-2 mm. If it is a chip, remove any loose particles. Vacuum up the dust.

5. 5

   Wet sand with 400 grit

   Wet the block and the tray and sand in circular movements with light pressure for 2-3 minutes until the area is even. Dry with a cloth and check that there is no shine left in the area you are about to fill.

6. 6

   Mix and apply the filler

   Mix the resin kit following the ratio on the pack, usually 100:2 or 1:1 depending on the brand. Apply it with a plastic spatula in layers of 1-2 mm, slightly proud of the tray surface. If the scratch is deep, apply two coats with 30 minutes between them.

7. 7

   Leave it to cure

   Leave it to cure for 24 hours at 18-25 degrees, without touching it and without showering. In high humidity (typical of windowless bathrooms on the coast) or below 15 degrees, wait 48 hours. Ventilate with the window open.

8. 8

   Sand in three stages

   With a wet block, level the repair with 800 grit until you cannot feel a step when you run your hand over it. Move up to 1200 and finish with 2000 to remove the sanding marks. Wipe clean with a damp cloth after each stage.

9. 9

   Polish and bring up the shine

   Put a small amount of polishing compound on a microfibre cloth and rub in circles for 2-3 minutes until the shine returns. Remove the tape, wipe off the residue and compare with the rest of the tray from several angles.

10. 10

    Renew the seal

    If the silicone around the perimeter is blackened or coming away, remove it, clean the joint and apply anti-mould sanitary silicone. Leave it for 24 hours without water before showering again.

Before you start: what kind of damage does your tray have?

Resin shower trays (Silex, Stone, Solid Surface, mineral filled) are a solid material with a surface layer. Nearly always the damage stays in that layer: scratches from dragging a stool, marks from a bucket, a chipped corner or a dull circle where limescale has built up. All of that can be repaired.

What a kit cannot repair is structural damage. Do this test before buying anything: dry the tray, hold a torch flat against the surface and look along it for cracks. If the crack is a hairline that does not catch your fingernail, it is only on the surface. If your nail sinks in, the crack runs several millimetres deep, splits the drain area or runs from one edge to another, the tray is broken. Also put a foot next to the crack: if the tray moves or sounds hollow, there is no support underneath and no filler will fix that.

What you need and what to avoid

A white gelcoat or sanitaryware repair kit is sold at Leroy Merlin and Bricodepot, and there are also two part resin fillers that do the job. An epoxy putty such as Plastic Padding Chemical Metal will fill deep chips, but once you paint over it the colour usually ends up more yellow than the tray. On a shower that is on show, always use a colour that matches the tray.

Choose the shade first. White trays from different makers vary: off white, pure white, ivory. If the kit does not match, find the RAL number or the colour name on the tray's data sheet, or write to the manufacturer. Test the shade on a hidden spot and wait for it to cure, because these kits change colour as they harden.

Avoid abrasive cleaners such as green scouring pads, scouring powder and neat bleach, which leave micro scratches and take the last of the shine off. Do not use paint stripper or acetone on the resin either: they soften it and make the damage worse.

Common mistakes when repairing a resin tray

• Sanding dry. It creates dust that gets into the pores and scratches more. Always sand wet, with foam blocks and light pressure.
• Jumping straight to a very fine grit. If you start with 1200 grit on a deep scratch you will not remove it, only polish it. Start with 400 if there is a step in the surface and work up gradually.
• Filling without drying. Moisture inside the crack stops the filler from bonding. Dry it with a hairdryer and leave it for an hour before filling.
• Mixing the hardener by eye. Two part fillers need the exact ratio on the pack. Too much hardener and it cracks; too little and it stays tacky.
• Using the shower too soon. Gelcoat and resin cure for 24 hours, and 48 if it is cold or very humid. A shower before then leaves a dull film.
• Ignoring a water leak. If the tray has a crack that runs past the edge of the seal against the wall, water gets underneath and the damage carries on inside even though the surface looks fine.

When to call a professional or replace the tray

If the crack goes right through the tray, the drain is cracked, the tray flexes underfoot or there are damp patches on the ceiling of the flat below, stop patching. The tray has to be replaced. It is plumbing and building work: take down the shower screen, remove the old tray, adjust the waste, level, seal and refit the screen.

At Manitas Costa we can take care of removing and refitting the shower screen (removal €50-65, fitting a sliding front screen €90-140) and of resealing with anti-mould silicone (€40-70). The full tray replacement is done by our partner renovation firm, and the work is usually quoted together: send us a photo and the measurements and we will give you a fixed price. If all you need is to polish or fill a scratch, it counts as a small job on the hourly rate, €35-45 for the first hour and €28-35 for each hour after that.

You will find more in shower screen fitting and repair and in what shower screens and their fitting cost. If you only want to clean the tray, see how to clean a resin shower tray. If the tray is a new one, there is how to install a shower tray.

Coastal climate: limescale, salt air and damp

In Valencia, Alicante, Torrevieja and Benidorm the water is hard and leaves a film of limescale that many people mistake for a scratch. Before sanding, try diluted white vinegar and a soft cloth for a few minutes: if the film comes off, there was nothing to repair. Rinse well and dry.

In holiday flats where the shower goes unused for weeks, stagnant damp leaves dark marks on the seal between the tray and the tiling. When you repair the tray, change the perimeter silicone as well; it wears out sooner than the resin. We explain it in how to seal a shower screen.

With summer sun and hot showers, old resin can turn yellow. Polishing the surface brings back some of the shine, but an even yellowing cannot be corrected with a kit. If you are thinking of renewing the bathroom in a second home in Torrevieja or Benidorm, send us a photo and we will tell you what is worth doing.