This is a very commonly asked question!
Often renovators have left over paint after painting the deck or fence or even the entire exterior of the house and instead of wasting the remainder of it, they ask “Can I use exterior paint inside”? That’s a reasonable question!
Simply put, the answer is NO. There are many reasons why you shouldn’t use exterior paint inside.
Firstly, exterior paints contain something called mildew inhibitors. They used to use mercury; I’m not sure if they still do, but due to their toxicity you do not want them inside your home.
I can understand that you might think “but wouldn’t it be wise to use exterior paint in areas like the bathroom to prevent moisture or heat in your kitchen”, but this isn’t a good solution. In fact, an exterior paint can cause more harm than good by using it indoors because of the Volatile Organic Compounds, or what’s commonly referred to as paint fumes that it gives off.
You don’t want this anywhere near your kids or pets!
Secondly, exterior paints are designed to “chalk” as they weather. This is definitely not a good look inside your house.
Thirdly, you don’t want to use exterior paint inside as it is formulated to be more flexible than interior paints, because they are subjected to a wider range of temperatures. This means that they don’t dry as hard so they’ll always be a bit soft or sticky. Not a very desirable finish at all!
Here’s a suggestion that you may like to consider in wet areas! A good-quality interior latex
paint is plenty good enough for your bathroom. Use a bathroom / kitchen paint for these areas to stop mildew forming.
OH NO, I’VE GONE AHEAD AND USED AN EXTERIOR PAINT INSIDE! WHAT NOW?
If you have used an exterior paint inside, there are specific things you must do before you re-paint an interior surface that was already painted with an exterior paint. A paint specialist can help, but it is usually recommended to remove as much of the old paint as possible, sand the surface, wash and dry the surface, and then apply a stain-blocking primer to the walls like Dulux Precision Stain Blocker primer before you paint. This type of primer will put a barrier between the old paint and the new paint.
Remember that an exterior paint is made to withstand the elements because the weather can cause many problems if the paint’s viscosity isn’t up to par. The sun can cause the colour to fade, and the rain and snow can cause moisture build-up which may lead to cracking, peeling, and mould and mildew problems.
If you are in need of professional advice, feel free to call Allscale Brushworx, we are happy to assist you in any way we can.