How to Sand Paint on a Front Door [Repaint/Refinish]

by Margaret · Published July 21, 2020 · Updated July 18, 2020

**Our honesty policy: This post may contain affiliate links and I may be compensated if you make a purchase at no extra cost to you. Some are, some aren't--I do some comparison shopping. The important thing is you will know exactly what we are talking about. Drop a note/comment if you have any questions on the products as these are materials and tools we use on our own projects.

Sanding paint on a front door at night with a shop light highlighting the blemishes and a Makita random orbital sander making them disappear.

This article covers the basics and finer details on how to sand paint on a front door when refinishing / repainting. Specifically, this documents how we completed this step on our fiberglass front door, but it applies to any wood, fiberglass or any material exterior door (or furniture). These tips will make your paint job smoother and the final product will look more professional.

Fair warning

This post is VERY similar to the sanding primer post, but for those who hit this post first, welcome! And be sure to read on the rest of the process as this is the fourth post in this series–links to the others are at the end of this post.
Second, this assumes you have a good base of paint: two layers of primer and one layer of paint, minimum.
Third, it is important to have sanded the primer before the first layer of paint. Otherwise, you might be taking off a lot more of the first layer of paint as the grooves from the paint brush strokes are that much bigger.

As for the tools and materials involved…I did some comparison shopping. Here are the best prices as of 6/3/2020 just comparing between Amazon and Home Depot (all affiliate links, but hey, this is where I spent my money for this project too!):

TOOLS:

Makita Random Orbital Sander
220 Grit Sanding Discs
220 Grit Sandpaper
Shop Vac
Tack Cloth
Saw horses or anything nice enough not to scratch the other side will do. We used 5 gallon buckets.
Shop Cloths / Old T-shirts
Gloves or Aveeno –most sanding projects dry my hands out–nothing like a day of tile–but even after a day of tile, this Aveeno lotion is magic!
Your elbow grease
Patience –This is not the most glamorous step, but it is better than stripping the old paint off!

You’ve got this!

The main tool for sanding paint is a random orbital sander. Mostly because it does the big field places fast–as in 10 minutes max. You’ll spend a lot longer with 220 grit sandpaper, but the random orbital sander steals the show.

Warning: it is easy to get in trouble quickly–keep the sander moving and DO NOT APPLY ANY WEIGHT. Let the weight of the machine work for you!

Keep it clean!

When you are sanding the sandpaper will create some sizable chunks of gunk that you’ll want to shop vac up from time to time during the sanding process. They clog the sandpaper and give you an uneven surface otherwise.

There will be some sizable chunks of gunk that you’ll want to shop vac up from time to time during the sanding process. They clog the sandpaper and give you an uneven surface otherwise. Photographed is said gunk coming off the sandpaper. You can see some white spots on the sandpaper too.

Said gunk coming off the sandpaper. You can see some white spots on the sandpaper too.

When you shop vac the bulk of the dust and debris I recommend putting your fingers in front of the nozzle as a buffer. This way you are less likely to make contact with the door, creating a mark from the plastic nozzle on the fresh primer.

No contact marks here!

Sanding paint is your last chance…

Sanding paint is one of those mulligan steps. When painting the first layer and during the subsequent drying phase anything could get lodged in the paint or overlooked:

paint boogers,
places where paint is obviously thicker along an edge, or
a bug flew into the attractive wet paint.

This is your chance to smooth them all out.

If you don’t, the last layer of paint will only magnify the problem.

Sanding also allows the wood grain you exposed when stripping off the old paint to shine through again, rather than looking at brush strokes.

Before…

Light Reflecting Off Sanded Paint on the fiberglass door.

…after!

You can really see the faux wood grain on the front door here!

Work in a controlled-light area.

As you can see in all these pictures, we sanded at night with the help of shop lights. The ability to control the direction of light helps you see the blemishes better.

Wiping Debris with Tack Cloth

Lay the door flat.

A random orbital sander can easily do some damage, so it is probably obvious that sanding paint is a step best done with the door laid horizontal. Pop the pins out of the hinges and lay it flat. Sawhorses are nice, but 5 gallon buckets will do too.

Don’t forget to do a once over one last time before starting that last layer of paint.

Case in point: somehow we totally missed a huge section with the random orbital sander. We definitely sanded it the next day before moving on to paint.