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How to Seal a Bath: Tips and Techniques for Professionals

by Georgia Nunn 14 May 2024
How to Seal a Bath: Tips and Techniques for Professionals

Choosing the Right Sealant

When it comes to maintaining the condition of your bathroom, choosing the right sealant is key. The ideal sealant will ensure that your space remains waterproof, hygienic and ultimately mould-free.

When sealing your bath, a space repeatedly exposed to water, it is important to choose an appropriate sealant in order to protect your bathroom from water damage and prevent the growth of mould.

Some Key Factors to Consider:

  • Waterproofing - The main purpose of bathroom sealants is to form a watertight barrier, to inhibit water damage and leaks. The high-moisture nature of the environment means that waterproofing is essential, when shopping for sealants, look for products that have been certified and tested on their waterproofing performance.
  • Mould Resistance - The constant presence of moisture and high levels of humidity means that bathrooms are especially susceptible to the growth of black mould. To help prevent this you should look for a sealant with anti-fungal properties.
  • Durability - It is important to select a sealant with a high level of durability to make sure that the seal stays practical and protected against mould, moisture and dirt.
  • Ease of application - To make the application process easier, look for a sealant with high adhesion properties as this will make for both an easier and a more accurate application.
  • High Quality - Choosing a sealant from a reputable brand is important to ensure the longevity and dependability of the product.

Our Recommendations

Everflex Premium+ 500 Bath & Sanitary Silicone White 295ml

  • Delivers a high-modulus acetoxy cure
  • Permanently flexible
  • Will not discolour upon ageing
Buy Everflex Premium+ 500 Bath & Sanitary Silicone White 295ml

    Soudal Trade Sanitary Silicone White 290ml

    • UV resistant
    • Permanently elastic after curing
    • Resistant to abrasion and common detergents
    Buy Soudal Trade Sanitary Silicone White 290ml

      Everbuild Showerproof Bathroom Silicone White 280ml

      • Anti-fungal properties
      • Low viscosity for fast application
      • Permanently flexible

      Buy Everbuild Showerproof Bathroom Silicone White 280ml

      Tools and Materials Required to Seal a Bath

      Sealing your bath is easy with the right tools. Here are the materials you need to seal a bathtub, or replace the sealant around your existing tub. Here’s our list of everything we think you’ll need for a clean and professional finish.

      • Safety gloves - Optional but advised to ensure your safety in the process
      • Masking tape - To ensure straight lines and a neat finish
      • Utility Knife - To remove any old sealant and to prep the sealant cartridge
      • Sealant Gun - For ease of application
      • Silicone Sealant (of your choice) - Preferably one that’s formulated for the bathroom and is mould resistant
      • Silicone Smoothing Tool - For smoothing the sealant after application
      • A soft dry clean cloth
      • Tweezers - To remove any small pieces of remaining sealant

      Preparing the Bath Surface

      Removing Old Sealant

      Before applying any new sealant, you must completely remove the old sealant.

      Use the utility knife to remove any existing sealant. Move the blade flat against the old sealant line following the joins around the bathtub. Be careful not to scratch the surfaces underneath.

      Take your tweezers, and go back over where the old sealant was, to remove any small piece remaining.

      Clean the Bath Area

      To preserve the durability of the new sealant, it is important that the area is both clean and dry, as the new sealant will adhere much better to a clean surface.

      Remove any grease and debris with a clean cloth.
      Non-porous surfaces should be degreased with an alcohol or paraffin-based product (such as methylated spirit).

      Make sure to thoroughly dry the area before applying any sealant.

      Tape the Bath Edges

      To ensure a neat and tidy finish, place masking tape around the grout line which will stop the sealant from getting on any unwanted areas.

      Place masking tape along the edge of the bath (around 4/5mm) from the wall.
      Place another strip of tape along the bottom edge of the wall just above the bath.

      Applying the Sealant

      Before applying the sealant make sure to fill the bath with water, as when full, your bath will sink slightly. If you do not fill your bath before sealing, the sealant could crack when the bath shifts with the increased weight.

      Prepare the Sealant Gun

      Using a utility knife, cut the end of the silicone cartridge seal and screw on the nozzle. The nozzle should be cut at a 45° angle, so that it is able to fit closely into the joint.

      You should ensure that the nozzle opening is slightly larger than the width of the gap that you are sealing.

      Place the silicone cartridge into the sealant gun. Squeeze the sealant gun trigger, pushing the silicone until it comes to the end of the nozzle tip.

      Apply the Silicone Sealant

      When applying the sealant, you want to make sure you are as close to the bath edge as possible.

      While holding the sealant gun at a 45° angle, apply a uniform bead of sealant in a smooth movement around the edge of the bath, beginning in the furthest corner, working in an anti-clockwise direction.

      It is important to maintain the right working speed when applying the sealant, to ensure an even line of product.

      Smoothing the Sealant

      In order to smooth the sealant you can either use a sealant smoothing tool or a wet fingertip. It is important to wet your smoothing tool with soapy water so that the silicone does not stick.

      Using the sealant applicator, go over and smooth the sealant edge at the same 45° angle as applied.

      This is important to not only ensure no mould or bacteria get in behind the sealant but the angled edge helps to direct water back into the bath.

      Once the sealant has been smoothed, carefully remove the masking tape. This must be done cautiously to prevent the tape from dragging the uncured sealant and creating a feathered, ragged edge.

      Curing the Sealant

      The water in the bath should remain while allowing the sealant to fully dry, so that the seal will not be disrupted in any way. It should take around 24-48 hours for the sealant to cure properly.

      The drying and curing process is crucial to the functionality of the sealant, as it is during this time that the watertight barrier is fully bonded. Once the recommended drying time has elapsed, the water can be drained from the bath and the bath can be used again as per usual.

      Always make sure to refer to the manufacturer’s instructions on the silicone sealant as recommended curing times may differ.

      Finishing Touches and Maintenance

      Common Mistakes to Avoid

      Below are some common mistakes that people often make when sealing a bath:

      Not Allowing for Drying Time - Applying sealant to a wet or damp surface, or not allowing for curing time, will degrade the sealant, hindering its effectiveness.

      Not Removing Old Sealant Properly - Applying new sealant over old can both create an ineffective seal and spread any underlying mould growth.

      Insufficient Cleaning - Failing to thoroughly clean the bath surface prior to application can lead to poor adhesion and dirt getting underneath the seal, reducing the effectiveness of the sealant.

      Using the Wrong Type of Sealant - It is important to use a bathroom specific sealant due to the higher moisture and humidity levels in the bathroom. If a different type of sealant is used this may be ineffective and could cause damage to the surface.

      Benefits of Hiring a Professional

      Hiring a professional to seal your bath should guarantee you a smoother and neater finish on your sealant application as they will be more experienced in the task. By using a professional service, you will gain access to industry grade products and specialist knowledge that can help to prolong the longevity of your sealant.

      Frequently Asked Questions

      Can bathroom sealants be painted over?

      Acrylic sealants can be painted over however, due to the rubber-like texture of silicone sealants, they typically cannot be painted over.

      Are silicone sealants better than acrylic?

      Silicone sealants are preferred in bathrooms as they are significantly more flexible and moisture resistant.

      How often should bathroom sealant be replaced?

      The sealant should be inspected annually, and you should consider re-applying the sealant every 1-2 years, if any cracks or mould are present.

      Do I have to use a mould-resistant sealant?

      Due to the significantly higher moisture and humidity levels in the bathroom, it is advisable to use a mould resistant sealant in order to prevent mould growth and increase the durability of the seal.

      What if there's a large gap between my bath and the wall?

      For large gaps between the bath and the wall, you should consider re-positioning your bath closer to the wall if this is possible. Alternatively, you can use a backer rod to fill the gap, and from there apply sealant over it for a smooth edge.

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