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Ok so mist coating is a term bandied around quite a lot when decorating but do you actually know what mist coating is, how to do a mist coat and also when you need to do one? As always we have your back here at Decorating Centre Online and are here to teach you everything you need to know, without overwhelming you with too much technical info and putting it into a helpful set of steps!
To put it simply, a mist coat is a watered down coat of paint which is applied to fresh, dried, new plaster before you apply ‘full’ (non watered down) coats of paint. New plaster is a really permeable surface (which simply means it will soak up any moisture really quickly!) So watering down your first coat as a ‘mist coat’ will help the plaster to soak up the paint and create a bond between the new plaster and the paint. For new plaster it is critical that you start with a mist coat, which leads me quite nicely into my next section… what will happen if you don’t mist coat!
Really it's not an option not to do a mist coat as the consequences are quite the disaster! Without the mist coat you’re likely to have very poor adhesion between your paint and your plaster and quite often it will crack, flake or even peel off in sheets in some instances! As I mentioned, adding water to the first coat helps the plaster to really bond to the paint as it's able to soak it up due to the paint being thinner.
So now to the important part. We know what a mist coat is (a watered down coat of paint) and we know when we need to apply one (to newly plastered walls) now its key to understand how to apply a mist coat!
First up we need to understand what type of plaster you have as this will dictate the drying time of your new plaster and therefore the type of product you should be using on it!
1. Ensure your plaster is dry. Most new plaster in this day and age is a skim coat onto plasterboard and luckily dries out relatively quickly (you’re looking at 4 weeks tops!) If you want to speed up this process keep the air flowing in the room by opening windows and utilise your heating or a heater but remember to use this gently! If you don’t let the plaster dry out before you start you could end up sealing the surface which wouldn’t allow any water in the plaster out and could cause issues such as paint bubbling.
2. Select your paint! We can colour match any paint colour into any paint finish so your options here are endless! We have a helpful blog here covering which paint finishes we recommend depending on the room you’re decorating so if you’re not sure on which to go for, pop and give that a quick read! Most of our emulsions can be utilised as their own mist coat… don’t get sucked into marketing that names products ‘paint for new plaster’ etc as its really not necessary! The only products we sell that require a specific primer for new plaster are the Tikkurila Optiva emulsions (that use the Optiva Primer) or the Zinsser Perma White (which benefits from the Bullseye 123 in bathroom settings).
3. Mix up your mist coat! Each product will state on the back of the tin how much water you will need to add to create your mist coat however I’ve quickly listed below the water to paint ratio on our key emulsions:
Leyland Hardwearing Matt/ Johnstone’s Acrylic Durable Matt: 20% Water, 80% Paint
Leyland Hardwearing Acrylic Eggshell: 20% Water, 80% Paint
Leyland Vinyl Matt/ Johnstone’s Covaplus Matt: 10% Water, 90% Paint
I would recommend pouring out your paint into a paint skuttle, adding water from a cup or measuring jug and stirring with a paint stirrer. Don’t get too worried about being exact on the measurements, close enough is fine!
4. Now it’s time to get it on the walls. Rollering will be much easier for large areas but be mindful that as it's watered down it will splatter more. It’s a great idea here to utilise the covermasq dust sheets to protect the area! They’re pre-masked so you can stick to the top of your skirting boards and pull out the dust sheet to protect the floor! Don’t panic at this stage, the new plaster soaks in the paint at different rates so this paired with it being watered down will make it appear patchy in areas!
5. Check over your walls for any imperfections (such as plaster lumps etc) and repair. Then once your mist coat is dry it's time to apply your two top coats of paint. Remember this is the exact same product as your mist coat but this time without being watered down.
If your plaster has been a more traditional application like last and plaster, lime plaster or plaster onto stone it's going to take a significant amount of time to fully dry out. It's important you allow the plaster to fully dry and release all of its moisture over time (otherwise this can lead to issues such as paint bubbling or even damp in extreme cases) so you need to use a breathable paint. For lime plaster there are specific paints (such as Zinsser Grade 1) or for others you would use a contract paint (a paint containing no vinyl) such as the Leyland Trade Super Leytex. You would water down your first coat of paint (with the Super Leytex it’s 10% water to 90% paint ratio) to apply your mist coat then apply two top coats of Super Leytex that is 100% paint. These products can both be colour matched but remember the level of durability in the Super Leytex is low due to it being a breathable paint finish. Once your plaster is fully dried out (6, possibly 9 months down the line) you can then coat with a more durable finish (remember this isn’t the case with lime plaster, it will always require specialist paint like the Zinsser Grade 1).
So there you have it! It's really quite a simple process once you know how, especially as it's all done with one product! Just remember to add water as per the manufacturer's instructions on the tin, stir it thoroughly and don’t fall for marketing such as products branded ‘paint for new plaster’!
As always if you have any questions just drop us a message, call, email and we’ll talk you through anything you need to know!