Dr. Fixit Dampguard Classic — Two-Component Water-Based Epoxy Damp-Proof Coating for Internal Walls and RCC Water Tanks
Two-component water-based epoxy from Pidilite that damp-proofs interior walls and lines RCC water tanks — brushable over damp plaster, CFTRI certified for potable water contact.
What is it?
A two-pack epoxy coating (Dr. Fixit code 104) — resin base plus hardener carried in water — that cures to a hard, washable, anti-fungal film on interior plaster and concrete.
Where is it used?
Damp internal walls and ceilings, RCC overhead and underground water tanks, and hygiene-critical wall areas in pharma units, food plants and hatcheries.
Why use it?
It goes on over damp substrates without waiting for full dry-out, shows nil water absorption (ASTM C 870), and is CFTRI certified safe for drinking-water tanks.
How is it applied?
Mix base, hardener and water 1:1:1 by weight; brush two coats 6–8 hours apart; paint after 24 hours, or air-cure tanks for 7 days and rinse before filling.
About Dr. Fixit Dampguard Classic
Dampguard Classic sits in the Dr. Fixit waterproofing range as Pidilite’s answer to a familiar Indian site problem: interior walls that stay damp long after the monsoon, and RCC water tanks that need a hygienic internal lining. It is a two-component epoxy — resin base and amine curing agent with pigments and fine fillers — carried in water rather than solvent. That one formulation choice defines the product: it can be brushed straight onto damp concrete and plaster, thinned with plain water to working consistency, and used inside occupied homes without solvent fumes, before curing into a tough, hard film that stops moisture telegraphing through paint.
Space Arc Engineering supplies Dampguard Classic across Delhi NCR with pan-India dispatch, in the 500 g and 1 kg packs Pidilite lists — the 500 g pack sized for a single touch-up patch, the 1 kg pack for room-scale repairs and small tank jobs, and both bought in quantity by contractors relining tanks or treating multiple units in group housing. We see it used in two main situations: as a pre-paint treatment on seepage-marked walls where the leak has been fixed but dampness lingers, and as a CFTRI-certified inner coat for domestic and institutional water tanks. We will also tell you when it is the wrong product — it does not cure rising damp, and correct diagnosis matters more than the material.
The technical insight
Conventional epoxies hate moisture; Dampguard Classic is engineered around it. Because the resin and curing agent are dispersed in water, the coating does not fight the substrate for dryness — the water carrier evaporates while the two components crosslink into a continuous, hydrophobic film. Once cured, that film records nil water absorption under ASTM C 870, which is why damp patches stop bleeding through the finished paint system. Pull-off adhesion tested to ASTM D 4541 reaches 2.5 N/mm² with failure occurring in the substrate rather than the bond line — the plaster gives up before the coating does. Fungicidal additives keep the surface free of the black mould that damp Indian walls otherwise grow, and the cured film resists salt water, soap water, and mild acids and alkalis, so it survives repeated washdowns.
Where it is used
- Pre-paint damp-proofing of interior walls and ceilings showing seepage marks, flaking paint or salt staining
- Internal damp-proofing of RCC overhead and underground water tanks, including potable water storage
- Epoxy-cement putty (mixed 1:1 with OPC or white cement) for filling fine cracks in internal walls
- Dry-side treatment of walls backing bathrooms, kitchens and plumbing shafts where moisture migrates through
- Hygienic wall coating in sterile areas of pharma plants, food processing units and hatcheries
- Ceilings below wet areas in apartments that show recurring damp patches after leak repair
- Coat–putty–coat sandwich treatment on chronically damp internal walls
- Society and apartment overhead tank refurbishment during AMC rounds or pre-monsoon preparation
- Touch-up damp treatment on small residential jobs where a single 500 g pack is enough
Key advantages
- Applies directly over damp concrete and plaster — no long dry-out wait before treatment
- CFTRI certified safe for drinking and potable water contact
- Nil water absorption when tested to ASTM C 870
- Adhesion of 2.5 N/mm² (ASTM D 4541) with failure in the substrate, not the coating
- Anti-fungal, anti-microbial film that resists mould growth on damp walls
- Resists salt water, soap water, mild acids and alkalis — stands up to washdowns
- Water-thinned, non-toxic, non-flammable — no solvent odour in occupied homes
- High coverage of 6–8 m² per kg per coat keeps the cost per treated room low
- Brush or short-nap roller application — no specialised equipment or highly skilled labour needed
- 500 g and 1 kg packs let a small job be bought without leftover material going off
Limitations & considerations
- Not recommended for rising dampness — capillary moisture from the ground needs a chemical DPC remedy, not a surface coating
- Cannot be applied over existing paint, neeru/lime finish or POP; the surface must be stripped back to sound plaster
- Pot life is only about 40 minutes at 30°C, so mix small batches you can brush out immediately
- Do not apply below 10°C; curing also slows in poorly ventilated, humid rooms
- Water tanks need a full 7-day air cure and 6–7 rinses before refilling, or the water may foam
- It is an interior damp-proof coating, not a substitute for positive-side terrace or external wall waterproofing
- A barrier coating, not a crystalline or cementitious tanking system — it will not hold back hydrostatic pressure in basements or retaining walls
- Will not bridge active structural cracks or a live leak; those need crack injection or structural repair before any coating goes on
- Real-world coverage falls below the quoted 6–8 m² per kg on rough, porous or heavily profiled plaster
- Two full coats at 75 micron DFT are mandatory — over-thinning or a single coat is the commonest on-site failure mode
- Small pack sizes make it costlier per m² than bulk cementitious systems on large tank contracts
Selection & best practice
Diagnose before you coat: confirm the dampness is residual or migrating moisture — not rising damp — and fix active leaks at source first. Strip paint, neeru and loose material back to sound plaster; wire-brush, sand with emery paper and dust off thoroughly. Stir the base and hardener in their own packs, blend them into a smooth homogeneous paste, then let it down with water at 1:1:1 by weight — never more than that. Brush on the first coat, recoat after 6–8 hours, and hold off painting for at least 24 hours. For stubborn patches, sandwich a coat of Dampguard-cement putty between two coats of the coating. In water tanks, fill cracks with the putty first and allow 24 hours between coats — ventilation inside a tank is poor, so drying takes the full day — then air-cure 7 days and rinse 6–7 times with clean water before putting the tank back in service.
Hold the film thickness. Do not over-thin past 1:1:1 to stretch coverage — the specification is 75 micron DFT, and thinned or single-coat work is the commonest reason a Dampguard job under-performs, not a defect in the material. Brush and short-nap roller both work; lay the second coat perpendicular to the first so pinholes in coat one are covered by coat two. On tank jobs a wet-film thickness gauge is worth the trouble, because an under-thickness film means seepage returning within a season.
Specifications
| Nature | Two-component water-based epoxy (base + hardener) |
| Mixing ratio, by weight | 1 : 1 : 1 (base : hardener : water) |
| Pot life at 30°C | 40 minutes minimum |
| Surface drying time at 30°C | 1–5 hours |
| Intercoat interval at 30°C | 6–8 hours |
| Coverage as coating | 6–8 m² per kg per coat at 75 micron DFT |
| Coverage as putty (with OPC) | 0.6–0.8 m² per kg per coat |
| Water absorption (ASTM C 870:90) | Nil |
| Adhesion strength (ASTM D 4541:02) | 2.5 N/mm² (failure in substrate) |
| Coats recommended | 2 coats over a prepared surface |
| Application method | Brush or short-nap roller |
| Pack sizes | 500 g and 1 kg |
| Indicative MRP | ₹265 (500 g) / ₹460 (1 kg), per manufacturer listing |
Industry use cases
Residential & Housing Societies
Repainting stalls when seepage-marked walls keep rejecting putty and paint. Two coats of Dampguard Classic after leak repair, painted over 24 hours later, stop the patch reappearing through the new finish.
Water Tanks — OHT & UGT
RCC tanks in group housing and institutions develop hairline cracks and algae. The putty-plus-coating system relines the tank internally, and CFTRI certification keeps stored water potable after the cure-and-rinse cycle.
Pharma & Food Processing
Sterile and washdown areas need walls that tolerate repeated cleaning. The hard anti-fungal epoxy film resists soap water and mild chemical washdowns without breaking down.
Hotels & Hospitality
Damp guest-room walls get treated between bookings — the water-based formulation leaves no solvent smell, and the room can be repainted the next day.
Hatcheries & Agro Facilities
Persistently humid hatchery interiors grow fungus on bare walls. A Dampguard-coated surface resists micro-organism growth and hoses down easily.
Institutional — Schools & Hospitals
Campus water storage tanks and damp interior walls in older blocks, usually specified into vacation-period maintenance windows when tanks can be taken off line for the cure-and-rinse cycle.
Frequently asked questions
Will Dampguard Classic stop rising damp in my ground-floor walls?
Can I paint over it, and how soon?
Is it genuinely safe for drinking-water tanks?
How much material do I need for one room?
Can it also fill hairline cracks?
How much should I mix at a time?
Do I really need two coats, or will one thick coat do?
Can I roller it instead of brushing?
Will it waterproof a basement or a retaining wall under water pressure?
How we position Dr. Fixit Dampguard Classic
Dampguard Classic is the interior, negative-side specialist in the Dr. Fixit range — the right pick once moisture has already reached the room side of a wall, or when a tank needs a potable-grade lining. It does not replace source-side waterproofing: pair it with the Dr. Fixit Bathseal range when a leaking bathroom above is the real cause, Dr. Fixit Newcoat or Roofseal on terraces, and Dr. Fixit Dampfree where the diagnosis is true rising damp. Inside the Dr. Fixit line it sits alongside Dr. Fixit Pidifin 2K, a heavier-duty elastomeric coating also used for potable water tanks, and Dr. Fixit Pidiproof LW+, the integral compound dosed into the concrete at mixing rather than brushed on afterwards — new tanks are often cast with Pidiproof LW+ in the mix and lined internally with Dampguard Classic or Pidifin 2K. For positive-side cementitious tank waterproofing we also supply Fosroc Brushcrete and SikaTop Seal-107 as proven alternatives, and where the tank or basement is genuinely under hydrostatic head, Fosroc Brushbond TGP — a crystalline cementitious system that works from both the positive and negative side and is itself rated for potable water contact — is the correct specification rather than a brush-applied damp-proof coating. Space Arc stocks all of these systems — tell us the symptom and we will match the right one, not just sell the pail.
Fosroc Brushbond TGP — A specifier would choose Brushbond TGP over Dampguard Classic when the job is a below-grade or hydrostatic-pressure water tank or basement needing a crystalline cementitious tanking system rather than a simple internal damp-proofing coat.
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