How to Prep an Unfinished Wood Door

Before you stain an unfinished wood door, you’ll need to complete these steps to guarantee a beautiful finish. Simple step by step instructions with photos guiding you through the process to prepare an unfinished wood door for stain. We also share our tips for preparing, staining, and sealing your new unfinished wood door.

A Four Step Process

There are four main steps you should take before staining your unfinished wood door.

1. Modify the door.
2. Sand the door.
3. Clean the door.
4. Condition the door.

Tips to Preparing an Unfinished Wood Door

Before we get in to the details of each step, let’s give you some tips!

If you are replacing your current door, we recommend buying a slab door without mortis for hinges, locks, and handle because the holes for your hardware may not line up with a precut door.

Also, when purchasing a new door, take note of the thickness of your current door. If the thickness is too different, this may impact the alignment with the door jamb, as well as the hinge placement.

Make sure to buy your under door seal strip first, so you have it to reference for spacing.

Saw horses are great for this project because most of this project occurs with the door horizontal. The conditioning, staining, and sealing finishes are all better applied when the door is horizontal to prevent dripping and sagging.

Save any pieces of wood you cut off! You’ll want these pieces to test different stain colors.

Be patient! From start to finish, measuring the door to hanging the finished door, took us 5 days. We promise you though, the wait is worth it. Don’t rush the process.

Now, let’s get into the details of each step!

Supplies

• Saw Horses
• Ryobi Circular Skill Saw
• Ryobi ONE+ Fixed Base Trim Router
• WEN 3/4″ Electric Hand Planer
• Ryobi Wood/Metal Door Lock Installation Kit/Jig
• Ryobi Door Hinge Template Jig
• Diablo 1/2″ x 1″ Straight Router Bit
• Vacuum with brush tip
• Measuring Tape
• Sand paper (220 grit, 320 grit, and a dry sponge sander)
• Lent Free Cloth
• 8oz. Varathane Pre-stain Wood Conditioner
• Trimaco Supertuff Staining Pads

Step 1: Modify the Door

The first step to prepare an unfinished door for stain is to size the door and mortar holes for locks, handle, and hinges.

This is a process specific to your door frame and hardware choice. You need to make these modifications to your door prior to staining because of the amount of dust it creates and the need to sand and stain the modified areas.

Take some time looking at the fit of your current door in the door jamb. Is it too small? Do you see daylight anywhere? How is the spacing? This is how you will know if you need to make any minor adjustments to the next step, your measurement.

If your current door closes nicely and fits perfect, you can use the exact measurement of your current door to determine the size needed for your new door. Transfer the measurements exactly as is.

If you noticed a need for some adjustments, make note of where you may need to increase the length or width of your door and then mark your cuts.

When making your cuts, first cut the bottom of the door. If you need to make it more narrow, make your cuts with an electric planer on the side of the door you plan to put your hinges. Slab doors don’t have a definitive interior or exterior side; you will make that decision based on blemish or grain preference.

In the next step, you’ll need two people. Put the new door in place, with one person holding it upright. Center the door side to side in the door jamb. Now, shim the bottom of the door evenly all the way across. The shims are used to replicate the spacing for the seal strip.

Now, aiming to transfer the hinge mortis locations on the door jamb to the new door, take a pencil and mark the hinge locations on your new slab door.

Also, you’ll need to transfer the location of the lock and door set holes in your door jamb onto the new door. This simply identifies the height for your holes.

You’ll then need to determine the backset for each hole.  The backset is simply the distance from the side of the door to the center of the hole. To determine this, you’ll need your lock and handle set.

The most common backset is 2 3/8”, but 2 ¾” is also very common. The lock and handle set you purchase may also have an adjustment to provide both of these measurements. We chose 2 3/8” because we have glass in our door.

Now for your next set of cuts. Reading the directions provided with the hinge jig kit, mortis your hinge holes.

Repeat the above step using the lock and handle jig kit to mortis your holes for the lock and handle.

Step 2: Sand the Door

The second step to prepare a bare wood door for stain is sand the door. Manufactured doors are already pre-sanded. Even though your slab door may feel smooth to the touch, there are imperfections in the surface that need to be addressed. Sanding the wood will close the wood pours, helping to tighten the grains. This is important because the stain will absorb more evenly on smooth surfaces.

If you are using an unfinished door from a manufacture, you will want to give the smooth surfaces a fine sanding. Our door was relatively smooth, so we started with 320 grit sand paper. If your door is rougher, you’ll need to start with a 150 grit or 220 grit and move up towards 330 grit.

Remember to sand with the grain. You never want to sand against the grain because this will have the opposite affect and actually open the pours of the grain. Afterwards, use a fine dry sponge sander for a clean, smooth finish.

The areas you cut, including the bottom and hardware inserts will need a more aggressive sanding process. This is because the saw blade agitates the wood and opens the grain. In these areas, start with a 220 grit sand paper first, then progress to 320 grit and last, use the dry sponge sander for a smooth finish.

Step 3: Clean the Door

The third step to prepare a bare wood door for stain is to clean the wood surface of all debris and dust. First, brush off large debris. Mike enjoys using a leaf blower! No, seriously. It’s powerful and works well to remove even fine dust. Work smart, not hard, right?

Next, while using a brush tip, vacuum the door. Make sure to focus on the nooks and corners specifically where dust easily gets stuck. Last, using a damp lent free cloth wipe the door down. Then, let it dry.

Step 4: Condition the Door

The fourth, and final, step to prepare an unfinished door for stain is to condition the door with a pre-stain treatment. Wood conditioner is recommended for soft woods including pine, maple fir, alder, and birch.

Without a conditioner, you risk uneven stain application and splotchy coloring. Conditioning the bare wood it an easy process and can be done in as little as 30 minutes prior to staining.

Our wood door is made of fir. One half pint of Varathane Pre-stain Wood Conditioner is more than enough for both sides of the door. Just like with sanding, you’ll want to apply the conditioner in the same direction as the grain, not against it. One coat is all that is needed.

Don’t know if you need a pre-stain wood conditioner? Try this test! In an area that is less visible, press your thumbnail into the wood surface. Does your thumbnail leave a dent? If so, the wood is soft and we recommend to use a wood conditioner. If you’re still uncertain, there’s no harm in using a wood conditioner. Better safe than sorry!

How to Stain an Unfinished Door

Now your door is prepped and ready to be stained. This is quite a detailed process itself. For a step by step how-to, check out our post on How to Stain an Unfinished Door.