How do I gauge the quantities for a good mix?
It is very important that the quantities are accurately gauged so that you will achieve optimum strength and workability.
Choose a bucket that is marked off in litres on the inside. This will be ideal for measuring the sand and cement. The reason that we gauge by volume is that it is the most accurate way. Weight is less accurate for gauging the sand because it does not take account of the moisture content which can vary enormously.
A typical final coat Wizard mix would consist of 5 litres of cement, 15 litres of sand and 225 – 450g of fibres. A standard Wizard Fibre pack contains 1Kg of fibres. If you put one third of a packet (333g) with 5 litres of cement and 15 litres of sand then you will have a good mix.
What type of sand should I use?
We recommend ordinary building sand because it will give a smooth finish and will offer excellent strength characteristics. In practise though, Wizard Fibre will dramatically increase the strength of any mortar mix no matter what type of sand you use. We have used a variety of different sands in our trials and have found subtle differences in the results. There will be a variation in the grades of sand available from region to region so it is difficult to give definitive answers here. If you are in any doubt then we suggest that you do a small mix and render a test area. When it has set fully you can test it for adhesion, smoothness and impact strength. If you are happy with all of these then your choice of sand should be suitable.
Should I put an adhesive such as Unibond on the wall first?
This type of product will not react in any way with Wizard Fibre. If your wall is fairly coarse and is providing a good key then it won’t be necessary. If your wall is very smooth then you can use it to increase adhesion if you wish.
Should I put a waterproofer in the mix?
If you are going to paint the pond then it is important that you do not use a waterproofer because this would close the gaps between the sand particles and the finished wall may be too smooth for the paint to adhere easily. If you are not painting then the addition of a waterproofer will not in any way affect the Wizard Fibre.
Should I use a plasticizer in the mix?
Yes if you wish. A mortar plasticizer (a fluid available from builders’ merchants that is added to the water in the mix) will increase the workability of your mortar.
Do I need to apply a scratch coat?
A scratch coat is an initial render applied directly to the blocks/concrete to smooth the structure prior to the application of the final render. Whilst it is still fresh, the surface should be roughened slightly (normally scratched using a few nails protruding through a piece of wood) in order to make a key for the final render. It is not essential to put Wizard Fibre in this coat but it will add valuable strength to the structure if you do. The mix should be 5 litres of cement to 15 litres of sand.
The advantages of applying a scratch coat are manifold. If your wall is rough or it is indented because you have laid bricks around a curve, the application of a scratch coat will make it much smoother thus allowing you to apply an even thickness top render. If you didn’t do this, your render could vary from 3mm to say, 40mm thick resulting in poor strength. Another important reason is that the render mix with Wizard Fibre is fully hydrated at the time of application. If applied to a low porosity substrate such as engineering bricks, the drying process will be very slow. If applied to a dry scratch coat, the water will be absorbed by the scratch coat and so the top coat can be trowelled off and completed within a few minutes. Not only does this remove the necessity for you to return later (may be very difficult to reach!) but it will make the final coat stronger. When a fully hydrated render dries out, it shrinks. With Wizard you won’t get cracking but the fibres will be under tension. When applied over a scratch coat, the bulk of the water is removed before the chemical setting process and so your final trowelling will de-stress the fibres. This means that this coat will have greater elasticity before failure. In summary then, it is not essential to have a scratch coat but you will get a smoother and stronger job if you do.
Do I need to burn off protruding fibres with a blowlamp?
Not with this product. There are some other products on the market that do require this extra procedure, otherwise the protruding fibres will turn into needles when coated in paint. Those products are made from polypropylene and are many times larger in diameter. Wizard is made from very fine glass strands that tend to lay flat during trowelling thus removing the need for burning off.
Do I need to paint the finished wall?
All untreated cement finishes will raise the pH of the water to a point that will cause harm to your fish. This is easily prevented by painting the walls with a proprietary pond paint. You could avoid this by adding a waterproofer to the mix whilst rendering and then allowing the finished pond to stand full of water for several weeks before re-filling with fresh water. Usually the better option is to paint the pond.
What type of pond paint should I use?
All proprietary pond paints are suitable for use over Wizard Fibre. Bituminous paints are easy a quick to apply but they are usually the least durable. We recommend a polyurethane paint (such as G4) that should be applied in three consecutive coats to give a smooth and durable finish. This paint is similar in appearance and consistency to varnish and should be applied only when the final render looks and feels dry. If you apply it to a moist render the paint will not adhere. There are some epoxy (two pack) pond paints available. These are excellent and are very durable though they do tend to be the most expensive.
Is a mix with Wizard Fibre difficult to apply?
Not at all. In fact for an amateur plasterer it is much easier to apply than a standard render because it is more sticky and adheres to a vertical surface more easily.
Can I mix Wizard Fibre with concrete?
Yes. At rates even as low as 1kg of fibres per cubic metre of concrete, you will improve the strength of your concrete. Steel reinforcement will give you the strongest structure but only if the steel is correctly placed so that you can take advantage of its tensile strength. This is a complex procedure and to place steel in the concrete incorrectly is a waste of time and money. Additionally, if the steel has only a thin covering of concrete, it will be liable to rusting which can lead to the failure of the structure. The addition of Wizard Fibres is a much simpler task for the amateur pond builder. The maximum addition rate that we would recommend is 200g of fibres for 20 litres of ballast.
Can Wizard be used for other building and plastering purposes?
Certainly. This product has many uses for the general builder, roofer and plasterer. Shrinkage cracking is a major headache for anyone using cement renders and for making cement borders and flashings. Wizard Fibre increases the versatility and durability of a mortar and once you have tried it, you will wonder how you ever managed without!