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Garage, cellar, laundry... the floor of some utility rooms, in cement or raw concrete, often remains in the state for a long time, until it is considered too dusty or only sad and dull. If you decide to paint your bare soil, first check the porosity of the substrate.
Its degree of permeability determines the good behavior of the painting. The trick is to test the drop of water. Pour a little water on the screed: if the liquid is quickly absorbed, the porosity of the soil is satisfactory and the belt can adhere to the support without underlay.
On the other hand, if the water stays on the surface, the soil is not sufficiently permeable. It should then be treated with hydrochloric acid diluted with water. On new soil, hydrochloric acid removes laitance from the cement; while it deeply disinfects ancient soils.

Decoration: need an undercoat?

FAQ - 💬

❓ Do you always need to use undercoat?

👉 If you are covering a dark colour or a surface that's never been primed or painted, you will need to use an undercoat. It can also provide a better coverage and hiding power than just applying extra top coats.

❓ When should you use undercoat?

👉 Undercoat is often required to seal unpainted surfaces or prepare the surface for painting. If you are transitioning from a dark to a light colour, the undercoat will help to obliterate the colour beneath. This will allow your chosen topcoat to achieve an unrivalled depth of colour.

❓ Do I need undercoat on painted wood?

👉 You may need an undercoat for wood, but there is no need to apply any primer, as the surface is already painted. If it is not practical to sand down to remove the sheen, an “adhesion” primer like Zinsser B-I-N will help your paint bond to the surface. It has the additional benefit of blocking stains and odours.

❓ Do I need undercoat on painted walls?

👉 No need to undercoat emulsion on walls , but you should be prepared to cut in the edges 3 times, and apply at least 2, possibly 3 coats overall, depending on your brush, technique, surface and paint. But don't think you need to buy in a special tin of primer for the first coat.

❓ What happens if you dont use undercoat?

👉 Primer Seals the Drywall The main purpose of this adhesive substance is to seal the drywall paper. Without it, waterborne paints, which have a latex binder, soak into the porous material unevenly, creating noticeable blotches and rough areas.

❓ Can you skip an undercoat?

👉 One more coat of undercoat should suffice on your doors and frames before you apply your topcoat Lester. Like i said before, skip the undercoat and go straight on with the satinwood if that's what your using but a coat of undercoat prior to using the satinwood would not do any harm.

❓ What happens if you don't undercoat before painting?

👉 However, because it absorbs so well, without a primer coat, you'll experience uneven coverage, especially along drywall seams. This means you'll need to apply more paint to finally get an even coat. Even then, you may still find yourself repainting again sooner than later.

❓ What happens if you don't undercoat wood?

👉 Omitting the primer is a mistake for several reasons, however, and you're likely to be disappointed with the final results, no matter how many coats you apply. Apart from the fact that you'll probably get uneven coverage and bleed-through, the finish coats are more susceptible to peeling, chalking and other defects.

❓ What can I use instead of undercoat?

👉 Can Emulsion Be Used As Undercoat? Yes, you can use water-based emulsions as an undercoat and then overcoat using a water-based gloss or satin finish. While this would not be done by a professional decorator due to it leaving a less impressive finish, if this is all you have at your disposal, it will be perfectly fine.

❓ What happens if you don't use undercoat on wood?

👉 Omitting the Primer Moreover, the water in the paint will raise the grain, especially around knots. The second coat may correct these flaws somewhat, but because you don't have a binding undercoat, the paint will probably begin peeling in a year or two.

❓ Is it OK to paint without primer?

👉 However, because it absorbs so well, without a primer coat, you'll experience uneven coverage, especially along drywall seams. This means you'll need to apply more paint to finally get an even coat. Even then, you may still find yourself repainting again sooner than later.

👉 Undercoats have been formulated to do a specific job. They basically seal a surface and prepare it for the decorative or, top coat. They prevent surfaces from soaking up too much paint, they prevent colours and stains from bleeding through and they ensure adhesion and prevent peeling.

👉 Previously coated surfaces should only require an undercoat if you are wanting to apply a water based paint over an unknown or oil based paint, if there are stains present or if the surface is rough or peeling, resulting in prep such as sanding or filling.

👉 Undercoat is an extra layer of paint, usually applied after the primer and before the topcoat of paint or varnish. Are the two interchangeable? The short answer is no. it is advisable to use a primer to treat new surfaces and undercoat when repainting a surface.

👉 No need to undercoat emulsion on walls , but you should be prepared to cut in the edges 3 times, and apply at least 2, possibly 3 coats overall, depending on your brush, technique, surface and paint.


Video Instruction: How to Undercoat Skirting Boards. Painting and Decorating