My kitchen cabinets have a groove/design routered into them. I want to make the fronts flat and paint them. What do I use to fill in the grooves?

You will need three items, all very cheap. You will need a small tub of air spackle, it may be also be referred to as “lightweight” spackle. Your next item is a 1 1/2 inch flexible putty knife, and finally a 100 to 120 grit sanding sponge. When you get these items, open the spackle, get yourself a plastic sandwich bag and put a couple large tablespoonfuls into it. work the spackle down into the corner of the bag, squeeze out the air and tie it off. Put the lid back on the spackle tub so it doesn’t dry out. Your baggy looks like and will function like a cloth cake decorator. Snip off the corner of your baggy making a small hole for the spackle to sqeeze out. This will deliver the spackle as you need it without it drying or making a mess. When you run out, get another baggy. Are you going to take the doors off, or paint them hanging? Either way, sqweeze a portion of spackle onto the putty knife and glide over the groove keeping it center of your knife. Press down on your knife, and let it flex as you travel the length of the grooves. Keep skimming of the excess, and refill your knife as needed. The grooves should be full and clean, flush with the wood on both sides. Let your doors dry overnight then lightly sand with the sanding sponge… Do not press hard, be gentle and let the sanding sponge do the work. I would recommend that you spackle twice to ensure a solid flush work on the doors. When you paint, you will never know there were once grooves.

One good product for that is Bondo ­ yes, the same product that is used to fill in automotive dents and creases. It¹s a two-part product that you mix on a flat board and then spread with a putty knife. After it hardens you can sand it smooth and paint right over it. It does not shrink and spreads very easily. You have to be careful to mix only as much as you can spread smooth in 3-5 minutes because it hardens quickly. For your purposes a lump about the size of a golf ball should be about right. They provide a scoop that is about that size in the package. Bondo makes the automotive product and also an Œall purpose product ­ both are available at my local Home Depot ­ and probably yours.

I had this same problem in a remodel and what I ended up doing was buying a door skin, about $18 and cut pieces using the original doors as templates. Apply with liquid nails, sand the sides smooth and put any finish you want on it, including stain. This saved so much time and energy. If you are going to paint you can use a cheaper product called Masonite. It is quick, easy and gives a very smooth finish to work with.