Can I Paint Over Polyurethane? (Read This Caution Before You Do)

Can I paint over polyurethane? It's not quite that simple so read this first to understand which situations you can and cannot paint over polyurethane.

So many people will think they maybe they have to sand it, maybe they don’t. 

Some may make the mistake of not sanding, despite how important it actually is to sand before you paint when you are working on something coated with polyurethane.

Thankfully it is not too hard to do, and there is not much more than you would have to do painting anything else.

But it is best to follow our tips so that you get it right and properly prepare the wood so that the paint doesn’t peel away.

Here's how it's done...

What is Polyurethane?

But what is polyurethane? Polyurethane is used often in coatings for wooden tops, often used in kitchen countertops, shelving units and so on, this is a coating that is usually only applied to wooden homeware.

But it does have other uses, polyurethane is used in our lives way more than we may realize.

It is also used as; insulation for refrigerators, building insulation, furniture cushioning, mattresses, cart parts, coatings, adhesives, tires, wooden panels, shoe soles, and sometimes sportswear too. 

Polyurethanes are versatile, modern, and safe. As a wood item coating, polyurethane is very hard and durable and it protects things such as your kitchen units from scratches or scuffs.

This is also commonly found on wooden floors, doors, and perhaps your dinner table if it is wood. 

How to Paint Over Polyurethane

So now we know what polyurethane is and what it does, so now we need to know how to paint over it.

Well, with a little elbow grease it is easy, you just need to ensure that you will have everything you need to get the absolute best result out of your wood and paint as you possibly can.

All you need is some patience, dedication, and the items listed below. 

What will you need?

• Lint-free clean cloths.
• Wood Filler. 
• Face Mask. 
• Gloves. 
• Mineral Spirits. 
• Protective eyewear. 
• Paintbrushes. 
• Oil-based primer. 
• Oil-based paint.
• Sandpaper (fine).

Steps:

1. First of all, check the labels and instructions of the products you have chosen to use.

Put on your protective gear, mask, gloves, and goggles, to protect yourself from harmful chemicals.

Ensure that your area of work is well ventilated and that you have somewhere to dispose of any rags that get soaked in mineral spirits or paints, soaking these in water prior as they may be very flammable. 

2. Remove any hardware, if you are working with cabinets or kitchen storage, remove cabinet doors or knobs, if working with a few cabinets then you can leave these in place, detaching them may make this job easier for you.

3. Now you want to clean and sand the surface. Use the mineral spirits to clean the wood wipe it in a circular motion with your lint-free cloth, removing dirt, grime, stains, and anything else unsanitary or unsightly from your wood.

Once this is clean wash the cloth and now get onto sanding.

You will want to use fine grade sandpaper for this, this removes the polyurethane from the wood, you do not need to remove it all, you will just need to remove enough so that the paint adheres to the wood. 

Take your time with this and it will pay off. It is very important to do this. 

4. Now that you have sanded down the wood, you’re past the most tedious bit, well done!

Next we prime! Priming the surface of the wood is important, it will allow your paint to stick better and it will stop any stains that are on the wood from seeping through the paint.

You will need to leave this to dry overnight for the best results, it may be necessary to do a second coat if you can still see wood grains through the primer. So prime it and put your feet up for a while. 

5. Has the primer dried and its looking good?

Fantastic! Now, we paint.

This too will take time, you need to paint the first coat and allow it to dry overnight, once you have done this and it has dried, you will have to add a second coat and leave this to dry for up to 72 hours before using as usual. 

Then, you’re done!

Safety

Safety is imperative. Some of what you will be working with can be toxic if breathed in or is flammable.

You need to ensure that your work area is well ventilated and that you dispose of your cloths carefully as these will be flammable.

Stay wary of latex or water-based paints over polyurethane, the finish may crackle, and remove this would be very difficult. 

Oil-Based Polyurethane

Oil-based polyurethane has an amber due and this type will continue to amber and darken over time.

This type of polyurethane takes longer to dry and cure, you can only apply one coat in 24 hours, if you apply this to your floor, you must wait 24 hours before walking on it. 

The smell of this polyurethane is very potent and emits a very strong chemical odor and noxious fumes while it dries, this is why you should wear a mask when you are around wet polyurethane. 

Water-based Polyurethane

Water-based polyurethane is clear and will remain so for a lifetime on your wood, it also fries much faster than oil-based polyurethane and you can apply up to 4 coats in just one day.

You could walk on this while wearing socks after 4 or 6 hours of application.  Water-based polyurethane has no smell, it is also safer to apply and you do not necessarily require a mask to work with this.