Advice On Mixing
Jonathan Baxandall, Altro’s regional technical service manager, gives the low down on tools and techniques for mixing resins and DPMs:
THOROUGH and complete mixing of any resin system is critical to the success of your application whether applying a two component liquid DPM or a heavy duty 9mm polyurethane crete product.
Making use of the right mixing equipment for the product and mixing in accordance with the manufacturer’s instructions are essential. Failure to do so can result in incomplete mixing, leading to poor application characteristics or partially-cured resin that will fail to give acceptable performance.
The curing of a resin product is achieved through a chemical reaction, normally when a base and hardener are combined, to set the system solid. If all of the reactive components are not fully mixed together the chemical reaction may be compromised, failing to work fully causing a loss of performance within the finished product.
When mixing two component ‘paints’ and DPMs, it is best to use a drill and paddle type mixer. Ensure the drill is powerful enough to turn the material over, remembering that for systems where aggregates or powders are added, the system will become thicker during mixing. Pre-mix the base prior to adding the hardener to ensure it is uniform.
Take care not to incorporate too much air at the mixing stage as all incorporated air needs to escape prior to curing of the resin. Mixing paddles that draw from the bottom to the top can be used to help minimise air entrapment.
Incorporate all of the resin, including from the bottom of the bucket. It could be an expensive and messy mistake to pour un-mixed resin onto the floor to find it not cured later on. If necessary, transfer the mixed product to another clean bucket and mix again – this way you make sure nothing remains unmixed on the bottom.
The thorough mixing of dry screeds cannot be achieved using a drill and paddle and instead a rotary drum or forced action mixer will be required (Daines or Rotamixer). Pre-mix the base and hardener using a drill and paddle, to start the chemical reaction before adding to the aggregate.
Mix in accordance with the manufacturer’s instructions ensuring the full time is given to the mixing so that all of the aggregate is coated. Look out for ‘dead’ spots in the mix where the aggregate remains dry and uncoated in resin and also watch out for old partially cured resin from previous mixes falling into your mix.
Polyurethane crete products will require a forced action mixer and mixing times often in excess of two minutes to allow all of the components to be mixed and for the hydration of the cement contained within the aggregate to start.
Short mixing times can result in stiffer mixes that are hard to spread and close. As with dry screeds, watch for dead spots and old resin falling into the mix.
This article has been reproduced from the Contract Flooring Journal website. You can find them at www.contractflooringjournal.co.uk.