When it comes to staining, pre-stain wood conditioner is often the answer to help your wood stain more evenly. But is it really necessary?
I have my thoughts on pre-stain wood conditioner, but instead of just sharing those, I thought I would actually put it to the test so you could get unbiased results.
So let’s dive in.
The Experiment
This experiment was pretty straightforward. We tested out both water-based and oil-based pre-stain wood conditioners. We also tested out a DIY pre-stain alternative that is commonly known as water-popping. Don’t be impressed by the fancy description, this is just applying water to the surface of the wood.
Before applying the pre-stain, we sanded each board with 120-grit, 180-grit, and 220-grit sandpaper to make sure the surface was properly prepped for stain. As we saw in last week’s stain test, sanding makes a big difference in how the stain is absorbed.
For this experiment, we used pine (which is notorious for staining blotchy) and red oak, which tends to accept stain very evenly.
Since every piece of wood is unique and can accept stain differently, it was important to test the exact same piece of wood to see how the pre-stain affected the stain results. We taped the wood at the halfway point and applied pre-stain to one half and did not apply pre-stain to the other side.
We followed the instructions on the pre-stain cans exactly. Water-based and oil-based pre-stains have different instructions, so always be sure to follow the recommended instructions.
For the water-popping, I ran my rag underneath the faucet (we have highly purified water) and then applied an even layer of water to the surface of the wood. I let the water sit for a couple of minutes and then wiped off the excess. After waiting 30 minutes for it to dry, I lightly sanded with 220-grit sandpaper. Essentially I followed the water-based pre-stain instructions for the just-water experiment.
Once ready for stain, I removed the tape and applied stain. People often use the water-popping method prior to oil-based stains to make the wood stain richer, so both the water-only and the oil-based wood conditioner received an oil-based stain. The water-based pres-stain received a water-based stain.
Again, I applied the stain according to the instructions on the can, which differs for oil vs water-based stains.
The Results
Oil-Based Pre-Stain Wood Conditioner
The oil-based pre-stain wood conditioner made a big difference in the splotchiness on pine, especially around the knots which tend to be the trickiest areas to evenly stain. It’s not perfect, but it’s significantly more even.
On oak, there isn’t an obvious difference.
When I was in the middle of the stain test, I had another idea. Does applying multiple coats of pre-stain prevent blotchiness even more? Here are the results.
The middle was the control (aka no pre-stain), the top had a single coat, and the bottom had two coats of pre-stain. I think the bottom is marginally more even, but I’d be curious to try this again around a knot where we saw the biggest issues in the previous example.
As I’ve mentioned before and I’ll mention again, every piece of wood is unique and can accept stain differently. The particular piece I did the 1 coat vs. 2 coat experiment on was already pretty consistent, so it was difficult to see as dramatic of a difference as the prior piece.
Water-Based Pre-Stain Wood Conditioner
The water-based pre-stain wood conditioner results weren’t as dramatic as the oil-based results, but again, that might be because this particular section of wood did not have any notoriously difficult knots.
It might also be because it’s a water-based stain. That’s one of my next stain tests: comparing water vs. oil based-stains of the same color to see if there is a difference in results. When building this DIY dining table, we tested a water-based stain on pine and noticed it was less yellow and stained more evenly than pine tends to. Will those results stand true across multiple colors?
On the pine, the stain color appears slightly lighter and more even on the side that was treated with pre-stain wood conditioner.
On the oak, there doesn’t appear to be much of a difference…however, please read my note below about water-based stain and oak.
Water-Popping
Water-popping was a big fat waste of time in this experiment. You can see that there is almost no difference between the samples.
I will say there might be a case that it could be beneficial: if you are using a water-based stain. The water can cause the grain to pop, resulting in a not-so-smooth finish (see photo under the “what woods don’t need pre-stain wood conditioner” section).
You always want to pop the grain yourself before staining so that you can sand your wood back down and minimize the overall grain raising. Pre-stain is very effective at this, but if you don’t have pre-stain available, water can be an option.
Which wood types need pre-stain wood conditioner?
Pre-stain wood conditioner makes a big difference on soft and porous woods like pine. Other wood types that it can make a big difference on are fir, maple, birch, and poplar.
What woods don’t need pre-stain wood conditioner?
Hardwoods like oak and walnut, might not need pre-stain wood conditioner, but think of it like insurance. You spent all this money on a nice hardwood and then you go to stain it. Chances are, you’ll be fine and it’ll stain very evenly, but there is always a slight chance that this particular piece of wood is going to be a little blotchy.
Would you rather take the risk or apply pre-stain wood conditioner and know that you got the most even result possible? It’s up to you, but personally, I’m going to take the extra few minutes to apply a pre-stain.
For oil-based stains, it’s up to you, but when applying water-based stains, I have a different opinion.
Though we didn’t see a dramatic case in this particular experiment (remember, every piece of wood is unique), I would highly recommend always using a pre-stain wood conditioner when applying a water-based stain on oak.
Why? Because water can cause the grain to pop, resulting in a fuzzy or prickling texture. Sometimes it’s subtle, but sometimes the grain raising is dramatic like in the photo below.
That piece of wood had been sanded well and was very smooth before applying the pre-stain wood conditioner. Had I not applied the pre-stain and sanded it down again before applying my stain, the water-based stain would have caused the same reaction. You would have either been left with a piece that was pretty much guaranteed to cause splinters, or you would have had to sand it down and stain all over again.
Because I always want my projects to be smooth, I always recommend using a water-based pre-stain wood conditioner before applying a water-based stain.
So all that to say, I always recommend using a pre-stain wood conditioner. The results will be the most obvious on softwoods like pine, but it can add some piece of mind on hardwoods like oak.
