Getting a professional Plastering FinishPlasterwork or plastering has been used as a building technique for centuries. The pyramids of ancient Egypt have plasterworks that are made of calcined gypsum more than 4,000 years old. Greek and Roman ruins have evidence of plastering that could have been lime plaster. A lot of architectural masterpieces especially during the Gothic period have superb plastering that have stood the test of time.
What are the types of plaster?
There are two general kinds of materials for plastering: gypsum based and cement based. Gypsum based plastering are used for interior finishing while the cement based plastering is for exterior finishing. Gypsum based plasters are susceptible to moisture and damp so cement based plastering can be used on interior walls that are prone to moisture and for interior walls that need thicker plastering. The common gypsum cement plasters are:
- Browning - this is a backing coat plaster that comes in pink. It sets in 1 ½ hours so you have to mix a batch that you can quickly finish. This type is ideal for absorbent surfaces like bricks and hollow blocks. The usual application thickness is a 10 mm.
- Bonding - this can be used on non-absorbent and dense materials. This plaster will also adhere to a surface previously treated with PVA (polyvinyl acetate).
- Finishing - this is applied over a browning or a bonding plastering. This is the best kind of plastering as it's normally applied as the last coat. Ideal thickness of plastering is 2mm thick.
- Hardwall -plastering is basically an undercoat plaster.
Note that plaster works on indoor walls only. Take precaution when mixing water and plaster. Use clean water and add plaster to the water and not the other way around
DIY is a leading pastime in the UK today. For those who are not well-versed on the art of plastering (yes, it is an art) here are some information that might prove useful to you.
Tools Needed for Plastering.
You cannot expect to be a certified DIY plasterer if you don't have the right tools. For starters you would need:
- A bucket for mixing your plaster or dry wall adhesive. The bucket should be flexible enough for you to just bend the sides to take out hardened plaster.
- A featheredge is needed for plasterboard application.
- A steel float is also called a plasterer's trowel
- A hawk is used to hold plaster as the plasterer uses the trowel to transfer plaster from the hawk to the wall.
- A plasterer's float made of polycarbonate is used for rendering.
- A string line and a plumb level
- A claw hammer
What plaster to use for what particular surface
Before you buy your plastering material, make sure that you but just the right amount for plaster ahs a very short shelf life. A rough guide in estimating is a 10 kg plaster should be enough to cover 1.5 square meters at 10 mm thick. The same amount would be enough to cover 5 square meters of 3 mm thick plastering.
- Browning plastering containing perlite should work well with coke breeze, bricks, clay tiles, concrete tiles and thermalite blocks.
- Bonding plaster with vermiculite is recommended for cork slabs, concrete, PVA treated surfaces and stonework
- Metal lathing plaster containing perlite, vermiculite and a rust inhibitor is best for wood wool slabs and expanded metal lathing.
- One Coat Plaster can be used for any surface either as an undercoat or as a finishing coat.
Skimming a Wall
"Skimming" means plastering a surface to make it smooth. It is actually the top coat or finishing coat of a wall. What is quite challenging in skimming is the fact that plastering materials dry quickly. Don't get frustrated if you can't do a great job at first. Skimming is quite challenging and it is to your advantage if you don't take on a big job at first. It is ideal to mix a batch that you can finish before the plaster hardens. Practice on some spot until you think you have gotten into the groove of skimming. If you have wasted packs of plastering without improvement, best if you call in a professional.
Here are some rules to follow when skimming a wall.
- 1. Make sure that the wall surface is ready for skimming. If you are skimming plasterboard then there's no need to prep the surface. If your project is skimming over an old surface, better coat the surface with diluted PVA to avoid cracks.
- 2. Make sure that all your tools are clean: bucket, trowel and floater. A small amount of old plaster in the new mix could make a disaster on your skim.
- 3. When mixing, add the water to the plaster slowly. Mix it well with a stick or mixer drill.
- 4. When plastering do not do walls that are in an angle. Do opposite walls first.
- 5. Make sure that the room is kept sufficiently cool. Turn off heaters if applicable.
- 6. When plastering a wall, turn off the electricity running through the wall as wet plaster conducts electricity.
- 7. Load your hawk with the plaster. If it's the right consistency, the plaster will not fall off.
- 8. Spread the plaster on the wall making sure that the float is at an angle with the wall. Cover as much wall as possible with 2mm plaster.
- 9. After plastering the wall, wet a brush and remove any unwanted plaster from adjoining walls.
- 10. Allow the plaster to dry a little before you use our float to smoothen the plaster. This is where experience and practice will come in as gauging the wetness or dryness of plaster is quite tricky. If you float too soon, the plastering might come off. If you float too late, the plastering might be too hard to smoothen.
- 11. After using the float, wait another 30 to 40 minutes before polishing the wall. Wet the wall with a large brush and use the trowel to polish your plastering.
Leave the wall to dry for a day or so.
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"plaster should be added to water "not the opposite" also it should be 2 coat for skimming to produce a better finish"