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Product Data Sheet

Crystoflex Max

Two pack, flexible, cementitious waterproofing membrane for positive or negative water pressure.


Crystoflex Max is a two pack, flexible, cementitious waterproof membrane designed for both positive and negative waterproofing for most building and construction substrates.

Crystoflex Max comprising of a liquid component of selected polymers and a powder component of selected cements, fillers and aggregates.

Crystoflex Max was formulated for demanding waterproof applications including immersed, potable water or ponding situations, positive or negative applications, resistance against hydrostatic pressure, under-tile, under-ground and other construction substrates.

Crystoflex Max complies with AS/NZS 4020:2002 Testing of Products For Use In Contact With Drinking Water - Australian Water Quality Centre Report Number 4007/92.1595 and meets the 'Green Star' environmental criteria.

In ponds and water features where an aesthetic appearance is required, Crystoflex Max can be top coated with Duram Primeseal which is compatible and enhances the performance of the entire waterproofing system.


Crystoflex Max is suitable for many waterproofing applications, but is particularly useful for areas requiring hydrostatic pressure resistance and immersed applications including:
• Water retaining structures such as concrete tanks, reservoirs, ponds, pools, fountains and water features.
• Crystoflex Max is suitable for contact with drinking water.
• Basements, foundations and tunnels.
• Positive or negative water pressure waterproofing.
• Retaining walls, planter boxes.
• Roofs (top coated with Azcoflex TR or Azcothane as recommended).
• Under tile waterproofing on balconies, terraces, podiums and decks.

Suitable Surfaces

Crystoflex Max is suitable for use on the following correctly prepared surfaces:
• Concrete, cement, cement render, polymer render, block work (preferably filled and vibrated to ensure the absence of voids), brick, FC and CFC sheeting, blue board, timber, masonry and metal after application of a suitable metal primer.
• Suitable for application on damp cementitious surfaces.


The information contained in this product data sheet is typical but does not constitute a full specification as conditions and specific requirements may vary from project to project. The instructions should be considered as a minimum requirement but the applicator or contractor must use their skill, knowledge and experience to carry out additional works as may be necessary to meet the requirements of the project. Specification for specific projects should be sought from the Company in writing.


Crystoflex Max is flexible and can withstand normal building movement, shrinkage and hairline but it has limited elongation and hence will not tolerate excessive movement or cracking of the substrate. Cracks and gaps must be independently sealed and waterproofed.

Benefits and Advantages

  • Suitable for contact with drinking water.
  • Meets the 'Green Star' environmental criteria.
  • Very low VOC levels.
  • Non-toxic.
  • Designed for applications where hydrostatic pressure resistance is required.
  • Suitable for immersion in water.
  • Two pack yet flexible.
  • Quick drying.
  • Can be applied to damp surfaces. It will dry faster on damp surfaces than Crystoflex.
  • Can be topped, tiled or coated.
  • Suitable for use in confined areas.
  • Compatible with most tile adhesives.
  • Can be coated.
  • Can be rendered with a polymer render or standard render with bonding additive.
  • Protects concrete against CO2 degradation.
  • Permeable to water vapour and therefore allows substrate to breath.
  • Can be used with and without a primer. However, refer to relevant project specifications.


Precautions in Use

The product is considered low risk if used properly as intended. Observe safety precautions on packaging and MSDS. Powder contains cement and until fully wet the inhalation of powder dust should be avoided and the wearing of a suitable mask is recommended. The use of rubber gloves and eye protection is recommended.

Priming and Surface Preparation

Good preparation is essential. Surfaces must be sound, stable, dry, clean and free of dust, loose, flaking, friable material and substances that may diminish adhesion.


» Exposed reinforcing steel must be treated for rust and coated with suitable anti-corrosive and anti-rust treatments (as for concrete spalling).
» Concrete surface that is rough, pitted, contains blow-holes and honeycombed areas must be suitably filled with high tensile strength, non-shrink  mortar and allowed to fully cure.
» Block work, which should have been properly filled with concrete and vibrated to ensure that no voids are present within the block work, must be properly pointed up.
» Metal sheeting should be treated for rust and coated with a suitable metal primer.
» Cracks should independently treated and sealed, or opened to a depth of approximately 20mm and 6mm wide and filled with Crystoflex Max.

Surfaces must be clean and free of surface imperfections, mould, fungus, contaminants, adhesion reducing substances, waxes, oils, dust, loose particles, gypsum plaster, paint and efflorescence.

Crystoflex Max can be used without priming. However priming with Duram Primeseal and Primeseal MC enhances the performance of the entire waterproofing system including its  hydrostatic pressure resistance.
If priming, then  prime with Duram Primeseal MC (preferably) or Duram Primeseal applied at no less than 1 Lt per 3m² and allowed to dry.  Excessively porous, friable and dusty surfaces may require an additional priming coat. The primed surfaces should have a solid, opaque appearance. Please refer to the product data sheets of the stated primer. Allow primer to fully dry.
Alternatively, Crystoflex liquid diluted 10% with clean water may be used as a primer for non-critical or undemanding applications (although Primeseal is preferred) applied at 3 to 4 m² per Lt and allowed to dry. Note that this method does not provide hydrostatic or evaporation of entrapped moisture from the substrate protection.
Timber (particularly particle board which should receive two priming coats), roofs and negative surfaces must be primed with Duram Primeseal.

Duram Primeseal MC may be applied to damp surfaces (but free from ponded or running water) which must become dry to allow the product to dry.


Detailing Preparation

Apply an adequate flexible polyurethane sealant, in accordance the manufacture's instruction and tool off to form a solid, coved or 45º fillet extending at least 10mm on to the adjacent surfaces. Apply the Duram membrane directly over the sealant and on the adjacent surfaces.
Alternatively, to corners of large cementitious tanks a high tensile strength, non-shrink mortar or Duram Crystoflex should be applied to form a fillet thereby eliminating 90 degree angles.
For Additional waterproofing protection the following additional steps should be taken:
Lay a strip of Duram Leak-Seal Tape (self-stick, butyl mastic waterproofing membrane with a polyester backed reinforcing fabric) over the cured polyurethane sealant (as described above) pressing it firmly on the surface. Apply the Duram membrane directly over the tape and on the adjacent surfaces.

Joins, Gaps and Cracks
Joins, gaps, cracks and around penetration should be suitably filled and sealed with an appropriate elastomeric sealant, preferably a polyurethane sealant, and allowed to cure.
Recommendation: The movement of small cracks should not be underestimated and should be at least covered with a flexible polyurethane sealant or additional coats of membrane.
Large or Live Cracks
• Large cracks should be routed out to form a 'V' and then filled and sealed with a polyurethane waterproof joint sealant as per the manufacturer's instructions. The sealant should be finished slightly proud of the surface and allowed to cure.
• Alternatively, rout out to a depth of 20mm and 6mm wide and fill with Crystoflex Max. Note: The cracks movement must not exceed the elongation tolerances of the membrane.
• Over these areas the membrane should used in conjunction with a reinforcing fabric (Duram Durascrim), i.e. embed the Durascrim in to the first membrane coat and then apply a top saturating coat. Allow to dry. Then apply 2 to 3 further coats over the Durascrim extending at least 150mm other side on to the substrate.

Joins - Particularly in CFC Sheeting and Timber Sheeting
Ideally the sides of the sheets should be fully coated with a flexible polyurethane waterproof joint sealant prior to butting the sheets together.

If not, the joins should be suitably filled and sealed with an appropriate elastomeric polyurethane waterproof sealant and finished flush with or preferably slightly proud of the surface and allowed to cure.

After priming, as required, lay a strip of Duram Leak-Seal Tape over the join, pressing it firmly on to the substrate. The Duram membrane is then be applied as described under 'Large or Live Cracks'.



• Mixing should be done with a mechanical stirrer - hand mixing is not recommended. Whilst stirring, the powder should be slowly added to the liquid. Stir until the mix is smooth, lump free and homogenous. The mixing ratios should be as supplied.
• If mixture sets before use, do not try to reconstitute by adding water or more liquid. This product should be discarded.

Application is usually by brush or roller. The final dry film thickness should be at least 1.5mm to 3mm depending upon the waterproofing requirement applied. Each coat should be applied at approximately 1mm wet film thickness -  in 2 to 3 coats approximately 1 day apart (maximum 3 days). If no primer has been used then lightly pre-dampen the substrate with clean water. Allow previous coat to fully cure / dry before applying the next. In confined areas such as tanks, the humidity in the tank may inhibit proper curing and artificial ventilation (preferably warm air) should be blown into the tank.

• Small ponds, fountains, retaining wall, roofs, concrete slabs: Apply a minimum of two coats to give a dry film thickness of at least 2.0mm .
• Large tanks: Apply a minimum of three coats to give a dry film thickness of at least 2.5mm.
• Swimming pools: Apply a minimum of three coats to give a dry film thickness is at least 3.0mm. The membrane should be suitably rendered with a suitable bonding agent incorporated in the render then tiled with a tile adhesive designed for immersion.


The stated average coverage rate may vary depending upon type, condition, porosity, texture of the surface and application technique.


Usually 1 kg per m² per coat applied in a minimum of 2 coats and 3 for demanding applications, i. e. a 30kg kit will cover 30m² per coat.


Crystoflex Max is  dark greyish in colour.
Hint:Where an aesthetic colour is required, Crystoflex Max can be top coated with Duram Primeseal which is available in Off-White(STD) or Grey(MC) which are compatible and enhances the overall waterproofing system and provides a pleasing finish when top coated with your choice of colour.

Drying and Curing

Drying and curing of the product is affected by type, dryness and porosity of the surface, temperature, humidity, ventilation, climate conditions and application technique and therefore drying and curing can only be given as a guide.


Typically at 23ºC and RH of 50%:
» Touch dry:    2 to 4 hours.
» Set:               4 to 6 hours.
» Dry / cure:    12 to 24 hours.
In confined areas such as tanks, the humidity in the tank may inhibit proper curing and artificial ventilation (preferably warm air) should be blown into the tank.


Product should be stored in cool, dry area. Do not use if bag is damaged.
Shelf life is approximately 12 months if stored in unopened and original packaging in suitable storage conditions.

Clean Up

If wet, use clean water, ensuring run off does not enter the drains. Cured product should be placed into suitable containers and disposed of in accordance with local council regulations.

Tiling, Topping or Top Coating

Crystoflex Max can be tiled, topped or coated.
» Tiled: It is compatible with most tile adhesives.
» Topped: Can be topped with sand:cement topping, preferably with an added bonding agent.
» Coated: Prime with Primeseal and then paint or coat.
» Rendering: Apply coat of bonding agent (Duramax Maxibond) and allow to tack off. Add MaxiBond to render mix and apply as normal. 

Safety & Precautions

The product is non-toxic but good hygiene and industrial practices should be employed. The powder contains cement and therefore skin and eye contact should be avoided. Do not inhale powder while mixing. The use of a suitable mask, cement resistant gloves and protective clothing including goggles is recommended.
• If in eye: Flush thoroughly with clean water whilst lifting lid to ensure particles are properly flushed. Do not rub eye as this may cause scratching and greater irritation.
• If on skin: Wash off with soap and water.


For full safety data refer to the products Material Safety Data Sheet. Observe precautions as per label.

Tests and Technical Data

Adhesion to concrete and porous substrates:    ≥ 2.0N/mm
Hydrostatic water pressure at 3mm thick:
• Positive                                                        ≥ 10m
• Negative                                                       ≥ 3m to 4 m (depending upon the type of substrate)
Elongation (bend test):                                     ± 20%


Issued: 1 May 2012 | Valid to: 31 May 2020

Conditions of Use and Disclaimer

The information contained in this Material Data Sheet is given in good faith based upon our current knowledge and does not imply warranty, express or implied. The information is provided and the product is sold on the basis that the product is used for its intended purpose and is used in a proper workmanlike manner in accordance with the instructions of the Product Data Sheet in suitable and safe working conditions. Under no circumstances will the Company be liable for loss, consequential or otherwise, arising from the use of the product.


DURAM PTY LTD ABN 50 612 836 718
The Ultimate in Waterproofing & Protective Coating Technology

Duram Offices:
NEW SOUTH WALES: 51 Prince William Drive, Seven Hills, NSW 2147

 Tel (02) 9624 4077  Fax: (02) 9624 4079

QUEENSLAND: Unit 4, 29 Collinsvale St Rocklea, QLD 4106

Tel (07) 3255 6478  Fax: (07) 3255 6258