Dr. Fixit Crack-X Paste
Single-pack, fibre-reinforced acrylic crack filler for internal and external plaster — press it in, level it off, and paint over within a day.
What is it?
A ready-to-use flexible putty from Pidilite’s Dr. Fixit range, built on weather-durable acrylic emulsion polymer with graded fillers and reinforcing fibres. It meets ASTM C 834-91 and comes as a white, non-sag paste.
Where is it used?
Cracks up to 5 mm wide in internal and external plastered brick masonry — the shrinkage and movement cracks that show up on walls, ceilings and facades before every repainting cycle.
Why use it?
No mixing, no primer, no wastage. The cured filler stays flexible (60-110% elongation), so repaired cracks do not telegraph back through fresh paint the way rigid cement fills often do.
How is it applied?
Widen hairline cracks to at least 1 mm, clean and moisten the surface, press the paste in with a putty knife, and level. Recoat after 2 hours if needed; paint after the film has fully dried.
About Dr. Fixit Crack-X Paste
Anyone who has handled a repainting contract in India knows the sequence: the painter finishes, the client signs off, and within one monsoon the old plaster cracks reappear as fine dark lines through the new coat. The usual culprit is the fill itself — neat cement slurry or rigid putty that cannot move with the wall. Dr. Fixit Crack-X Paste was formulated for exactly this problem. It is a single-pack acrylic emulsion putty, reinforced with fibres and loaded with graded fillers, that bonds strongly to cementitious plaster and stays flexible after drying, so minor thermal and shrinkage movement in the crack is absorbed rather than re-cracked.
For contractors, the practical appeal is speed and predictability. The paste comes ready to use straight from the container in 300 g, 500 g, 1 kg and 5 kg packs, holds its shape on vertical and overhead surfaces without sagging, and can be applied on damp plaster — a genuine advantage on Indian sites where walls rarely stay bone dry. It is water-based and very low in VOC, cleans off tools with soap and warm water, and takes any polymer-based paint after 24 hours. Space Arc Engineering stocks the full pack range and supports painting contractors, societies and facility teams across Delhi NCR and pan-India with material and application guidance.
The technical insight
The chemistry does the real work here. As the water phase evaporates, the acrylic emulsion particles coalesce into a continuous elastomeric film that locks the graded fillers and fibres into a tough composite plug inside the crack. Two properties matter most on the datasheet: elongation of 60-110% and a minimum tensile strength of 1.1 MPa. Together they mean the cured fill can stretch across a crack that breathes with daily temperature swings instead of debonding or splitting — which is why rigid cement fills fail and this does not. The fibres act as micro-reinforcement, distributing stress along the fill and resisting the 18-22% drying shrinkage that would otherwise leave a depression; this is also why the method statement calls for a second levelling coat after 2 hours on deeper cracks. Adhesion to moist cementitious substrates comes from the polar acrylic polymer, which is why the TDS actually asks you to moisten the surface before application rather than dry it out.
Where it is used
- Filling shrinkage and movement cracks up to 5 mm wide in external plastered walls before repainting or applying a waterproof coating
- Internal plaster crack repair on walls and ceilings ahead of POP, putty and paint systems
- Treating hairline plaster cracks (widened to a minimum 1 mm groove) during pre-paint surface preparation
- Crack rectification on parapets, chajjas and facade bands as part of society repainting programmes
- Repairing plaster cracks around door and window frame junctions where masonry meets the frame
- Making good plaster cracks during flat handover, snagging and rental maintenance work
- Sealing fine plaster cracks on damp walls where solvent-based or cementitious fillers cannot be used immediately
- Crack treatment before exterior texture or acrylic emulsion topcoats on brick masonry plaster
Key advantages
- Single-pack and truly ready to use — no site mixing, no water dosing, no pot-life pressure
- Fibre-reinforced fill with 60-110% elongation stays flexible and accommodates minor crack movement
- Non-sag paste consistency works on vertical surfaces and ceilings with an ordinary putty knife
- Can be applied on damp plaster surfaces, keeping repainting schedules moving in humid weather
- Water-based, very low VOC, non-toxic and non-staining; tools clean with soap and warm water
- Overcoatable with any polymer-based paint after 24 hours, and tintable with water-based stainers
- Excellent UV and weathering resistance for exterior facades; meets ASTM C 834-91
- Small packs from 300 g to 5 kg let you buy to the job size instead of carrying dead stock
Limitations & considerations
- Strictly for cracks up to 5 mm wide — wider or deeper cracks need a mortar-based repair, not a paste filler
- Not for structural cracks, expansion joints or separation gaps; these require engineered repair or a movement-grade sealant
- Cannot be applied over cracks with running water — the crack must be damp at most, not actively leaking
- Do not fill cracks within POP or painter’s putty layers; the coating must be removed until sound plaster is exposed
- Drying slows significantly below 10°C, which affects winter application schedules in north India
- Drying shrinkage of 18-22% means deeper fills usually need a second levelling coat
Selection & best practice
Preparation decides the result. Rake out loose material and clean the crack of dust, oil and grease; hairline cracks must be widened to at least 1 mm with a scraper, because paste pressed onto a closed hairline sits on the surface instead of keying into it. On internal walls, remove existing POP or painter’s putty until plaster is exposed. Moisten the surface, then press the paste firmly into the crack with a putty knife and strike it level, working carefully to avoid trapped air pockets. Let the first application set for about 2 hours, then apply a second levelling coat where the fill has shrunk back — allow the first coat 4-6 hours to dry through. Give the completed repair a minimum of 8 hours before POP or painting, and use polymer-based paints only after 24 hours. Below 10°C, extend all drying times. Reseal the container tightly after use; unopened shelf life is 12 months stored cool and dry.
Specifications
| Appearance | White paste with fibre |
| Density at 30°C | 1.38 – 1.46 g/ml |
| Solid content at 30°C | 78 – 82% |
| Tack-free time | 10 – 30 minutes |
| Elongation | 60 – 110% |
| Tensile strength | Min. 1.1 MPa |
| Coverage | 25 – 30 running metres per kg (5 mm x 5 mm crack section) |
| Standard compliance | ASTM C 834-91 |
| Pack sizes | 300 g, 500 g, 1 kg, 5 kg |
Industry use cases
Housing Societies & Residential Repainting
The workhorse of society repainting contracts — crack filling across facades, staircases and common areas before primer, with small packs issued floor-wise to painting gangs.
Commercial & Facility Maintenance
Facility teams use it for rolling plaster crack repair in offices, retail and hospitality, where low odour, low VOC and same-week paintability keep occupied spaces in service.
Institutional Buildings
Schools, hospitals and government buildings specify it during annual maintenance because it is non-toxic, water-based and safe to handle in occupied premises.
Real Estate Handover & Snagging
Developers and finishing contractors use it to close out plaster shrinkage cracks flagged during snagging, giving a paint-ready surface within 24 hours.
Painting Contractors
Applicators standardise on it for pre-paint crack treatment since it tools like conventional putty, accepts water-based stainers, and will not stain or bleed through topcoats.
Frequently asked questions
What is the maximum crack width Dr. Fixit Crack-X Paste can handle?
How soon can I paint over the repair?
Can it be applied on damp walls?
Will it work on structural cracks in columns, beams or slabs?
How much do I need for my job?
Do hairline cracks need any preparation before filling?
How we position Dr. Fixit Crack-X Paste
Crack-X Paste is the pre-paint crack specialist of the Dr. Fixit building-repair line, and it works best as part of a system. For wider masonry cracks beyond its 5 mm limit, step up to Dr. Fixit Crack-X Powder, the mix-and-fill companion product. On exterior walls with widespread fine cracking, filling every hairline individually is rarely economical — fill the significant cracks with Crack-X Paste and finish with an elastomeric coating such as Dr. Fixit Raincoat over the full facade. Where crack filling precedes wet-area work, Dr. Fixit Pidifin 2K and Bathseal handle the waterproofing side. For genuinely structural cracks in concrete members, this product is the wrong tool: Space Arc supplies epoxy injection and structural repair systems from Fosroc (Nitofill range, Renderoc mortars) and Sika, and our team can help you distinguish plaster cracking from structural distress before you spend money on the wrong repair. As authorised distributor and applicator, Space Arc supports material supply and site guidance across Delhi NCR and pan-India.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.