FILL-FLEX

Yes, it’s a really good idea to finish with either Skim Flex (flexible skim-coat) or Fine Surface Filler. All Toupret products will adhere to Fill Flex once it is fully dried.

Due to its flexible nature, Fill-Flex is not easily sanded. Fill-Flex is reinforced with flexible fibres that allow it to move with the substrate. This flexibility is what prevents cracks from reappearing but it also means the product is resistant to sanding. Unlike traditional fillers that dry rigid and can be sanded smooth, Fill Flex remains slightly flexible even after drying. What should I do instead of sanding? To achieve a smooth finish: Apply flush to the surface. Immediately smooth the surface using your finger. Alternatively, use a slightly damp sponge. Remove excess product while it is still workable.

Yes, Fill-Flex can be used on exterior surfaces. It’s particularly effective for reappearing cracks outside, just as it is indoors. Areas that experience expansion and contraction due to temperature changes can benefit from a flexible filler. When using Fill-Flex externally: It is suitable for cracks up to 1cm deep (10mm) Ensure the surface is clean and dry before application Smooth immediately after applying All substrates should be clean, dry, sound, cohesive and hard prior to application. Concerned about surface matching? If you're repairing a textured or rendered surface and want a seamless finish, we recommend applying Skim-Flex across the whole surface area to ensure consistent texture and appearance. Using the correct product for depth and finish will ensure long-term durability and prevent exterior cracks from reopening.

Yes, but only on primed wood surfaces. Fill Flex is suitable for: Primed skirting boards. Primed door frames. Primed architraves. Other painted or sealed timber trims. It is not recommended for: Bare, untreated wood. Oiled or stained timber. Surfaces without a primer or paint base. Structural or load bearing repairs. Floors. Unprimed MDF. Because wood naturally expands and contracts, using a flexible filler between primed timber and walls is ideal for preventing cracks where different materials meet. If you’re applying filler between skirting and wall, ensure the timber is primed first for proper adhesion and long-lasting results.

You can apply a second coat of Fill-Flex as soon as the first is dry, which usually takes up to 24 hours. The total thickness of the application should not exceed 10 mm (1 cm).

For deeper cracks, choose Fill-Flex. For surface levelling, blending, or smoothing over moving surfaces (up to 5mm depth), choose Skim-Flex. Fill-Flex has a depth limit of 10mm (1cm) and is ideal for repairing small, reappearing hairline cracks. It’s fibre-reinforced, remains flexible after it's dry, and is resistant to sanding. This makes it perfect for targeted repairs where cracks are likely to reappear. Skim-Flex has a maximum application depth of 5mm, so it’s designed as a skim coat rather than a deep filler. It’s best used for surface matching and smoothing over areas that may experience slight movement. It can be applied across wider surfaces to create a uniform finish and can be sanded once dry for a seamless result.

No, scrim tape is not required when using Fill-Flex but can be used to reinforce crack even further. Whilst not strictly necessary, if you were to use Scrim Tape, you would fill the crack using Fill-Flex, then add the Scrim Tape over the top. Once dry, use a finishing or levelling filler to smooth surface. Traditional crack repairs often rely on scrim tape to reinforce the joint and prevent future splitting. However, Fill-Flex already contains reinforcing fibres within the formula. These fibres: • Improve adhesion • Bridge small gaps • Increase flexibility • Reduce the need for additional reinforcement. Because the fibres are built into the product, they effectively replace the need for scrim in most standard movement-related cracks (such as between skirting boards and walls). This simplifies the repair process and saves time during application.