

🧩 Build stronger, bond smarter — don’t let your projects settle for less!
WEST System 404-45 High Density Filler is a premium epoxy thickening additive designed to maximize adhesive strength and reduce creep in high-stress hardware bonding. Compatible with multiple WEST SYSTEM epoxy formulations, it creates a customizable, gap-filling slurry that cures to a durable off-white finish, making it ideal for structural fillets and demanding repair tasks.













B**I
Epoxy filler
Nice addition to west epoxy, thickens mixture and fills gaps, just as advertised.
K**A
Great filler
I use West System products exclusively when doing marine fiberglass repairs/modifications. There are many different filler options, so choose the one that best fits your needs. Mix the resin, add the filler and mix to your desired consistency, then apply. For me, usually similar to mayonnaise works best. Drying time will depend on your choice of hardener and if you've adjusted the resin/hardener ratio.
I**G
Solid
Must have for epoxy work, mixes well without clumps
C**E
Works as deisigned
Mixes well. Solid when set using West System products.
M**.
Great filler
Easy to thicken your resin with, great product. Makes really strong glue when mixed with epoxy resin.
J**R
Works good
We purchased this to fix our RV fill in a soft spot. First off it is easy to mix in with the kit but it does set up fast! So you need to be ready to go to pour when you mix it. It worked great for what we used it for, has been fixed for well over a year now and still holding strong.
A**R
Five Stars
Excellent product. Does what it's supposed to do, and a lot cheaper through Amazon.
L**Y
Love it
Great stuff.
Trustpilot
2 weeks ago
1 day ago