How can I tell if my interior walls were painted with latex or oil paints?

How can I tell if my Kirkland interior walls were painted with latex (waterborne) or oil paints?

Wall Painting
I’m painting the inside of my house. Should I paint my ceilings and walls the same color? I live in Kirkland.
July 21, 2016
Latex Paint
What’s the best way to select and store my leftover interior latex paint for my Kirkland home?
August 5, 2016

There’s a quick test you can do that will often give you the answer, but it is not always definitive. Pour or spray some water on the wall, leave it there for about 10 seconds, then wipe it off with a dry kitchen roll or something similar. If the water remains somewhat soaked into the wall, it it very likely a water-based paint to begin with. But if it wipes clean and dry, you can’t always tell if it is oil based for certain. Many water-based paints now repel water quite well, and will give the appearance of being oil-based.

To all intents and purposes, and for planning what to do with the next layers of paint, likely the most important aspect here is whether it will take a new coat of paint, what type, and what you need to do to the walls before you start. Let’s talk about all of that.

Prepping your interior walls for a new coat of paint

Much as I’ve always liked to just start painting directly onto walls, I’ve learned a few things from making that mistake. Even in living rooms or sitting rooms, moisture, grease and other forms of oil and liquid slowly but surely stick to the walls and even soak into it.

In kitchens, steam, food, condiments and all manner of materials find their way onto walls and ceilings. I remember when I daughter was a toddler sitting and eating in her high chair, I found food stuck to the ceiling above her. I never knew how exactly she got it there, but I guess she did it with a spoon or fork, perhaps slamming her hand down on it, sending the food on the other end of the ‘see-saw’ spoon high into the air. It was a fun thing to try to work out, but it meant we had to wash and clean the entire ceiling of the kitchen before any painting took place. So, too, did all the walls need a thorough degreasing with washing up liquid, a sponge and hot water.

For any new coat of paint to take well, there could not be any grease whatsoever. The paint might go on well, and look fine for a while, but any underlying grease will present a problem sooner or later, and at the very least, reduce the life time of your new paint project.

Bathrooms are another room type that need good preparation before painting. Washing the walls and ceilings, followed by a good airing out of the room will benefit the project that’s about to begin. Again, simple washing up liquid and hot water works great in almost any situation. Make sure the walls and ceilings are also rinsed of the washing up liquid, too. You want what is essentially a sterilized surface to begin with.

What’s on the other side of the wall?

I’ve also seen grease seeping through a wall from an adjacent restaurant. A pizza restaurant placed hot pizza on plates right beside a shared wall where, on the other side, a chiropractic clinic was taking care of patients. The owner – the chiropractor – said he would occasionally get a faint smell of garlic or something. What was happening was, over many years, the oils they sprinkled on pizzas would end up on the wall. That particular section of wall had been painted incorrectly (or they used the wrong paint type) and so, the wall was essentially porous. Oils soaked through the drywall, somehow made their way across studs or the insulation, then through the drywall of the chiropractic clinic. At first, I didn’t know what was happening, but upon investigation, we realized a significant amount of remodeling had to be done before any painting took place. In the end, we worked with the pizza restaurant owners to cover the cost of it all, and this time, we made sure to use an industrial grade paint on the restaurant side of the wall to repel any foodstuffs than make their way on to it.

Bathrooms need a certain type of paint

If you have kids in the house, and especially in the Pacific Northwest, a bathroom may never actually get the chance to completely dry out. On top of that, with kids using a bathroom, you get stains and soaks of all manner of liquids from toothpaste to hair conditioner.

Keep the air flowing through: I almost always leave bathroom windows open, and the door open, too. If the dead of winter, of course, you won’t want to do that, but a good central heating system can be very effective in keeping the air dry, and surfaces drying quickly. You’ll never keep them totally dry, but getting the right paint on in the first place will go a long way. Paint in a bathroom needs to be completely waterproof.

Kitchens need something special, too

I have general rule I have extolled to my own kids over the years. Anything your skin comes in direct contact with may enter into your bloodstream. That’s why, I tell them, you wear protective gloves when you are using any type of cleaning liquid. The same rule goes for paint you use in your kitchen. It is best if it can be completely cleaned regularly. That means you need a type of paint that can resist the casual contact with food or liquids, and therefore must also be 100% waterproof. It also must be able to resist a soft scrubbing when it comes to cleanup time. If you use ‘bedroom quality’ paint in a kitchen, you might be disappointed.

Make sure you tell your paint provider – or your painting contractor – what type of room you expect to be using the paint it. It might cost a few dollars more for the right type of paint, but it will be worth it when you see how durable and long-lasting your paint project will be.

Trim often gets the most wear and tear

You’ve probably noticed how scuffed up trim can get in a home. It’s especially true when kids are living there too. Consider using a high-use type of paint for such places, and keep a small supply of the stuff handy in case you need to touch up some places later. And remember, clean off the surfaces thoroughly before applying any paint.

See you all next week!

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