What’s the right way to use a sponge float?

Below, we offer a step-by-step guide on the right way to use a sponge float.

A sponge float is a versatile tool used by plasterers and tilers. It consists of a sponge pad attached to a flat, rigid back with a handle. Its main uses are smoothing out plaster and removing excess grout from tile surfaces.

It’s important to use a sponge float correctly to achieve professional-level results when plastering, avoid damaging tiles when grouting, and maximise material efficiency. Here’s how to use this nifty tool the right way.

The right way to use a sponge float

There are two main activities that call for the use of a sponge float: grouting tiles and plastering. Here’s how to correctly use this tool for each of these tasks:

1. How to use a sponge float for grouting tiles

Before applying grout with the sponge float, ensure the spaces between tiles are clean and free of debris.

Next, mix the grout according to the manufacturer’s instructions – aim for a thick, but spreadable, consistency.

Take your rubber float and press the grout between the tiles, ensuring there’s a generous amount of grout to fill every crevice. Press down fairly hard to remove any air pockets.

Initial cleanup

This step involves holding the sponge float at a 45-degree angle to scrape off excess grout without removing it from between the tiles. Move diagonally across the tiles to keep the edge of the sponge from sinking into the cracks and scooping out the freshly applied grout.

Because grout particles can quickly accumulate on your sponge float, it’s important to clean it regularly to prevent them from smearing on fresh tiles and grout lines. Keep two buckets close by. One for removing the initial bulk of the grout and the other for rinsing in clean water.

Finishing

Gently move the sponge float in a circular motion over the grout lines to smooth them out and perfect them. Grout lines should be slightly recessed below the tile surface.

Use the edge of the sponge float to define the edges of the grout lines, particularly where tiles meet right angles. If there’s some haze left behind on tile surfaces, you can use the sponge float to wipe it away, moving diagonally to the grout lines to prevent removing fresh grout.

Continue rinsing and cleaning until the tiles are clean and the grout lines are smooth and even.

2. How to use a sponge float for plastering

When it comes to plastering, the sponge float is only used for texturing after the plaster is applied with a metal trowel. Texturing helps smooth out the plaster, remove imperfections, and create a more adhesive surface.

After applying plaster as usual, leave it to begin to set, but not fully dry. It should be firm, but malleable to the touch.

Texturing

Submerge the sponge float in water, squeezing out excess to ensure it’s damp, but not dripping. Using circular motions, gently press down and move the sponge float over the plaster.

The porosity of the sponge will lift small amounts of plaster from the wall, creating a uniform texture. Keep stepping back and evaluating your work as you go – this will help to spot inconsistencies and rough patches.

Make sure you’re applying even pressure throughout.

Smoothing

The texturing process creates a slightly rough finish, and the smoothing process refines and evens it out, making it less pronounced but still effective.

Dampen the sponge float again and glide it over the surface, applying even pressure. Slightly press down the peaks created during texturing and fill in any small valleys to create a smoother, more even surface.

After smoothing, inspect your work from various angles to ensure it looks consistent. If any areas need further smoothing, do it while the plaster is still malleable.

Remember, if you don’t have the time, tools, or know-how to complete this job yourself, you can easily find Checkatrade-approved local plasterers by entering your postcode into the search box below.