How to use P-Tec 8400

Time To Get Your Fill! 

I had an interesting piece of walnut that wasn’t great for furniture but was going to make an awesome serving board. There were a few knot holes that needed filling and one corner that needed to be completely rebuilt. Wood filler was the solution I chose and I think you’d agree, it turned out pretty well.

What is wood filler? What’s it used for?

Wood filler is a substance that gets used to fill small holes or defects in wood or sheet goods like MDF and plywood. It can also stabilize wood that is affected by rot or insect damage. There are many different wood fillers available but here are the qualities that I look for:

• Dries quickly
• Can be machined, planed, and sanded
• Compatible with most finishes and paints
• Doesn’t shrink
• No odor 
• Simple mixing
• Food safe

There aren’t many fillers that meet all the requirements which is why my choice is P-Tec 8400. 

How to apply wood filler

Generally I find fillers are thicker than other products used to fill gaps like epoxy or CA glue. Because of that I like to use a flexible metal putty knife. I find that the plastic versions aren't rigid enough and you can't force the filler into the gaps effectively. The metal putty knife also makes a great stir stick and helps you mix the two parts really well. 

Simply take up some of the filler on the end of the knife and press it into the gap or crack that you're trying to fill. I like to go over the spot multiple times to make sure that I've got everything filled the way I want it.

Once I'm confident that the gap is filled, I scrape some of the excess from around the defect to reduce the amount of planing and sanding I'll have to do later.

How long does P-TEC wood filler take to dry

The literature that comes with the product says that it dries in 18 minutes if the room temperature is 22°C. The time can be reduced or increased accordingly depending on the temperature of your shop. I like to keep some of the extra filler material that I mixed accessible so that I can periodically check to see if it’s dry.

How to sand wood filler

Personally, I like to start with a small hand plane first. This removes the majority of the filler and smooths out a lot of the lumps and bumps prior to sanding. Don't fret, your hand plane won't be damaged by the filler nor will your blade become dull. 

Then I switch over to a random orbital sander and I stop sanding at 180 grit. It's not recommended that you go past 180 grit because the surface of the filler can become too smooth and finishes won't stick to it. If you are accustomed to using hard wax oils stopping at 180 will be natural. 

Is P-TEC 8400 paintable?

Absolutely! Not only does it except paint well but it also takes most clear coat finishes, oils, and waxes. Just be sure to not sand past 180 grit making the surface too slick. Always try a sample area first to make sure that your finishes compatible. 

I like using the natural flaws and sap lines in the wood in my furniture making but that sometimes requires a bit of repair. For dark knots and bark inclusions, P-TEC 8400 is a great choice. 

Shop P-TEC 8400 by Chill Epoxy

Prefer a video instead? Head on over to our YouTube channel to learn how to use a wood filler like P-Tec 8400.