Types of Abrasives for Sanding Wood Floors

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Floor Coat UK supplies four main types of abrasives for sanding wooden floors and flooring, Silicon Carbide, Aluminium Oxide, Zirconium/ Zirconia and Ceramic. We hope this guide to sanding abrasives provides a bit more information about the sanding discs and abrasives available.

Types of Abrasives for Sanding Wood Floors

Silicone Carbide

Silicon Carbide grain fractures into small pieces to sharpen and stay sharp however they do die very quickly.
They are designed for and more suitable for plaster, concrete and Granwood sports floors however they will dull more quickly on wood and are more expensive than Aluminium Oxide.

Aluminium Oxide

Aluminium Oxide has good friability under heat and pressure when sanding wood, the grains are sharp blocky fragments that renew cutting edges constantly, so are very good for finishing.

Zirconium/ Zirconia

Zirconium/ Zirconia have impressive durability and long life, even cutting rate and is good at dissipating heat. The grains fracture into small jagged pieces that stay sharper longer but can cause problems when finishing.

Ceramic

Ceramic abrasive grains resist fracture and have a long life. A good quality belt will do 30 to 40 metres; a ceramic belt has been known to be sharp after 200 metres. They are more costly but very tough and aggressive. They can deliver up to four times the performance of Aluminium Oxide and up to twice the performance of zirconium.

So on large jobs, they can be cost-effective as although the price per belt/disc is higher, it may well be a lower cost for the job overall as not as many are needed saving slightly on labour and time also.

A lot of sanders who use Ceramics do not knock nails down as the belts are great and will sand the nails however this can shorten the life of the belt.

Other things to consider when choosing your abrasives

What species of wood are you sanding?

Different species vary in how hard they are to sand. For instance, Maple is very hard. Pine is fairly soft and Oak is somewhere between the two.

How old is the floor?

What grit you start on depends on the condition of the floor and when it was last coated.

What machines are you using?

Not all manufacturers make all sizes in all abrasive types and grits. At Floorcoat UK we stock belts in 480mm, 451mm, 200, 250 x 750mm and discs in 200mm, 178mm, 178/22mm, 150mm and 90mm we have them all in stock.

Type of finish previously used on the wood floor?

If the floor has been previously waxed or stained you will want to remove this finish before lacquering or changing colour. It is vital when changing finishes that a floor is sanded well and a good primer is used. Talk to us at Floorcoat UK we can advise on this.

When the floor was last sanded?

This will make a difference if fairly recently done it could be a simple screen and recoat you would need a less aggressive approach maybe starting at 40 grit or it may not require a full sand, just a screen and recoat.

Budget versus time and quality and type of finish required?

If you are going to stain a much better, fine smooth finish is required to get rid of any sanding marks otherwise a stain will accentuate any marks. This should be taken into account when pricing jobs. As it is another level, especially for staining.

What type of finish you are going to be using?

For staining it is recommended to screen up to 150 /180 grit (anything over this will smooth the floor too much and will not take up the stain) but a thorough inspection of the sanding is needed before starting staining. Finish on 80 to 120 grit if you are using a floor lacquer or Hardwax oil, normally finish on 80 grit for oil and 120 grit for lacquer as oil requires a more open grain to be consistent.

Quality of Abrasives from the Manufacturer

  • Coatings of grains on discs and Belts vary from one manufacturer to another.
  • Some manufacturers use mixed grits to cheapen the products which affects the performance. This is something we do not do at Floorcoat, the discs/belts are coated in all the same grit for consistent quality.
  • Cheaper products have more gaps with big spaces between the grains; these wear out quickly and can produce uneven results. They do however stay cool but do not cut as well.
  • A more closed grain coverage on the abrasive produces a more even finish and has more grains to do the cutting, they are generally higher quality products.

Grades and Grit Selection

Abrasive Grades

  • 16, 24,36 Very Coarse for roughing
  • 40 to 60 Coarse for semi roughing
  • 80 medium to start finishing
  • 100 to 150 Fine finishing

Grit Selection

  • Start with a more aggressive abrasive then go through the grits, never jumping more than 1 grit. ( This is vital if you are staining) For instance, if you start with a 40 you would then use 60 then 80 grits and may finish with 120 if applying a stain. Otherwise, you will miss some of the floor or it will be too aggressive and leave marks. Floors needing lower grits to start 24 or 36 you still need to work through the grits. As the lower grit you go to marks will only be removed by going through the grits.
  • Make sure you change abrasives regularly
  • Thoroughly vacuum the floor before starting and between each grit, by vacuuming all debris from rougher grits, otherwise, failure to do this will put marks on the floor.

Aims

1. The first sand is to take off the finish.
2. To smooth out the pattern of the first sand, to create an even floor and establish any filling requirements.
3 & 4 To smooth out any marks and give a good smooth finish after filling and to finish the floor.

Tips

1. Sand along the grain not against it and keep the sander moving to avoid gouge marks.
2. Roughing should always be done at a slight angle.
3. Never skip more than one grit.
4. Avoid sanding too fast or too slow (you will miss or over sand).
5. Never sand over and over on the same angle alter it slightly to avoid rubbing and a build-up of heat, this will affect the amount of grain raising and denibbing you have to do.
6. Let the sander do the work (avoid pushing with too much downward pressure).
7. Start and stop with the belt sander up to avoid unevenness and swirls.
8. Make sure you use a hand sander flat not on an angle this will create unevenness.
9. Never denib after the first/ primer coat. If needed after the second coat before the final coat.

Conclusion

Choosing your abrasives is an individual choice based on the machines you using , the floor you are sanding and the desired finish. Hope these few pointers help you make the right decision for you.