WEST System 404 High Density Filler

Works great for many jobs that require a thicker epoxy for gap filling.

Perfect product for the application I was using it for.

The West system fillers are so great to work with. They Are consistent and do as advertised.

I used this to thicken epoxy for filling screw holes. I drilled pilot holes and threaded lag bolts into it. It seems strong enough for the application. If there's a better product available for this application, I haven't yet discovered it.

I used it for re- enforcing a composite fiber glass and aramid honeycomb panel. I needed a syringe in order to insert it into the panel. It does the job.

I have used this 404 high-density filler for over a quarter century both as a thickener and gap filler and whenever a bond had to withstand structural stresses. I had previously used sawdust for those filler applications but switched to the 404 fibers despite their much higher cost because they are finer and produce a smoother surface. The 404 fibers are also great for making strong fillets. You can easily form those fillets as smooth as if they were sanded: when the epoxy is no longer runny but before it sets completely, put a gob of hand soap or lotion on your fingertip and run it over the fillet to give it the shape you want -- the lotion keeps it from sticking to your finger, and you can easily wipe that lotion off the fillet after the epoxy is cured.

I am completely new to The West System Products. I purchsed the starter kit with Hardener and Resins, plus fiberglass and was extremely pleased. The project needed some filling in of gaps so I purchased the 404 High Density Filler. In the end it worked perfectly. My only suggestion would be to start with small batches as you learn how to work with the product. It sanded easily and was just what I needed.

Blended well (used heavy concentration as application was on a vertical surface...no sag) and set rock hard. Coarser surface than other fillers...harder sanding. Next time I'd spread a bit less, leaving 1/4"" or so to dress with another epoxy layet with fairing cmpd blend...easier to sand and smoother top coat.

We used this filler with 105 resin 206 hardener and 404 filler for laminating,filleting and glassing.I like this filler better than the 404 because it is easier to mix.

404 is the strongest of the adhesive fillers- it is also difficult to sand but that is not a negative when used properly. 404 makes a very hard and stiff fillet.