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The Art of Plastering A Step by Step Guide Paul Harper All rights reserved. No

The Art of Plastering A Step by Step Guide Paul Harper All rights reserved. No part of this manual may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the author. Copyright © Paul Harper 2005 The author cannot accept liability for the use of any of the materials or methods recommended in this manual or for any consequences arising out of their use. The author cannot guarantee the suitability of any recommendations made in this manual and shall not be under any legal liability of any kind in respect of or arising out of the content of this manual. 1 Introduction This guide will take you through each stage of plastering. The method has been proven during training courses to be the most successful format for complete beginners to achieve a professional finish. This does not mean you will become a plasterer overnight but you should be able to plaster a wall to a professional standard. The first wall you plaster may take all day – but taking the time to ensure your technique is correct will mean your speed rapidly increases. The best approach is to have a go – this is sometimes the only way some aspects of this guide will make sense (see practice page). If after having a go something does not make sense or you just can’t seem to get the results you want then help is at hand: help@diyplastering.co.uk Try to enjoy your plastering experience – you may get a few aches and pains but it will hopefully be a very rewarding experience for you. Using this guide…. Before you start plastering it is advisable to briefly read through the entire manual and view the DVD first. If some elements do not make total sense then do not worry – sometimes you just need to have a go. The DVD is designed as an aid only to clarify certain points within the manual. It should not be used independently of the written guide. The directions of application in this manual apply to people that are right handed. If you are left handed simply reverse them. (i.e. If right to left is stated then a left handed person will find it easier to reverse this to left to right). 2 Backing coat page 4 Suction test If the wall is dry the moisture will be sucked out of the plaster too quickly. Hawk & trowel control Ensuring accurate loading of your trowel. Top & bottom guide A horizontal guide for the top and bottom of the straight edge to help rule the wall 'flat'. Middle section Apply plaster slightly thicker than you need. Keep scraping this plaster off with the straight edge until the straight edge is in contact with the guides. Complete top section Apply plaster slightly thicker than you need. Rule this excess off by nibbling away a section at a time with the straight edge to ensure the flatness of the rest of the wall is projected right the way through to the top. Float The float should always be kept totally flat on the wall. This will push all the high areas into the low areas filling any hollows. (Can only take place when the plaster has firmed up.) Cut back Ensure edges and corners are flat. Skimming page 20 Keep clean The skim coat is only 2 -3mm thick so any grit can be a problem. Controlling suction If you don't have it under control then no matter how good your skimming technique is you will never be able to achieve a good finish. Application Skimming is definitely not a case of applying the plaster and smoothing out immediately – there are many situations that can only be resolved when the plaster begins to set or firms up due to the moisture being sucked out. Practising page 28 3 Section 1 The backing coat is responsible for flatness. The purpose of the backing coat is to achieve a totally flat surface – it doesn’t matter how rough it is as long as it is flat. Average thickness is 12mm. The skim (finish) coat is responsible for smoothness. A smooth finish is obtained by applying a skim coat of finish plaster. The skim coat is applied to the backing coat at a thickness of 2-3 mm. It is not designed to flatten, but is literally just a smoothing off coat. The Skim Coat is explained in section 2. All walls need a backing coat except…. Plasterboard walls. Plasterboard acts as the backing coat as it is totally flat. If for some reason the plasterboard is not flat then a backing coat of ‘Bonding Coat’ can be applied. Previously Plastered Surfaces For example – when the wallpaper has been removed in old houses the wall behind although flat may be in too poor a condition to apply paint. Therefore a skim coat should be sufficient. Thickness Average thickness of a backing coat is 10 to 12 mm thick. If the wall you’re plastering is flat and has no cables that need to be buried you may be able to apply a coat of 10mm or less. The thickness of backing coat will depend upon the wall you are working on. Sometimes the thickness will be set for you – if you have a door lining in the wall, then the backing coat should finish flush with this lining. If you have an external corner on your wall then your first job is to fix an angle bead on the corner – this will give you a straight edge to work to whilst also setting the thickness for the whole. If you have a wall with no external corner plaster this first – angle beads are explained later. Then once you are a bit more familiar with plastering the fixing of angle beads will be a lot easier. 4 There are many different plasters that can be used for the backing coat: Sand based render mix The easiest backing coat for the beginner to apply is the traditional sand & cement render – it stays workable for hours (sets overnight), is very forgiving and always to be recommended. The only drawback is the mixing – which does take a little more effort to mix than the gypsum based plasters, but once mixed this effort pays dividends by giving you all the time you need to work on your wall without it setting. Sand & Lime mixes (cement is substituted with lime) – used in restoration work to give greater flexibility whilst allowing the walls to breathe. Mixing The ratio of 5 equal measures of sand to 1 measure of cement is adequate for most plastering jobs. Water should be added until the required consistency is achieved which is a matter of personal preference. It needs to be firm enough to ensure that it can ‘peak’ (Make a peak with trowel and it should stay there) If the peak disappears then it is too wet. The peak should be able to be made very easily. If force is required then your mix is too dry. It is essential that the water you are using for your mix contains a plasticizer. This is a liquid that is added to the water to ensure better workability. If this is not used then you can almost guarantee you will have extreme difficulty in applying your render mix. Adequate mixing is essential to ensure the plasticizer has worked throughout the whole batch of render. If you have the benefit of a mixer then you should leave it mixing for at least 3 minutes. If you are mixing by hand that is an awful lot of mixing with a shovel so it may be better to mix up in buckets with a whisk powered by a drill. It is worth noting that once the plasticizer has taken effect the mix becomes very creamy and wetter so you may find yourself having to add a few dry ingredients to stiffen the mixture up. Gypsum Based ‘Hardwall’ or ‘Browning – once mixed with water will set within 1½ - 2 hours. Is a direct replacement for sand & cement and can be used for all brickwork and blockwork walls. Ideal for smaller areas that can be comfortably completed within the setting time, although it is quite ‘sticky’ and can be harder to use than sand / cement Mixing Start off with ⅓ bucket of water and add plaster whilst mixing with whisk until you get the required consistency. No plasticizer is required. Bonding coat Bonding Coat - once mixed with water will set within 1½ - 2 hours This plaster does what it says and sticks very well to a wide variety of low suction backgrounds such as plasterboard or painted surfaces. Good for patching and repairing lath & plaster ceilings Mixing Same as for ‘Hardwall & Browning’ above There are many uploads/Geographie/ guide - 2023-05-30T081507.388.pdf