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West System 404 High-Density filler is an epoxy thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated. 404 can also be used for filleting and gap filling where maximum strength is necessary. Color: off-white.
404 Filler is currently back-ordered and we are unable to provide an availability date. West System suggests substituting 406 Filler for most applications.
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I need to adjust the angle of the propeller shaft strut. The mounting surface is not flat and has some voids that using a whim would leave gaps. Would product be sutible with the proper epoxy for such a repair?
If you are using it with epoxy to fill in the area, then bolting the strut, that would be fine.
JD Tech Team
I need to fill hardware fastening holes in my boat deck. Is 404 the correct product?
Thanks for the info. Howard
Generally 404 is a good choice for filling, but if extensive sanding is required a better choice might be 407 or 410 (see related questions and answers). I usually have 404 and 405 available.
Do you consider this the best filler product to use for filleting seams, or do you recommend another filler West System provides? I'm most concerned with strength, not weight or color. I'm constructing a stitch and glue dory, with fiber tape on seams and fiber cloth over entire hull.
So far, this is the best that I have found. I am an amateur, but I have used the West fillers extensively, and I have yet to be disappointed. I have tried other systems, but none allow for the mixing of filler to obtain the perfect consistency. Strength has never been a problem. Good luck..hope this helps...johnpaul
Home wrecker Home wrecker
Yes, the 404 Filler is an excellent choice for your application. Just be aware that this filler is difficult to sand, so extra care making a neat seam will benefit your finishing work later. Once you've completed taping, the 407 filler will be a good choice for fairing as it sands easily but will still add some strength to your hull.
Thank you for the advice.
Yes for strength it's the best you mite use micro balloons think its 410? For faring
I use the 404 quite a bit for my primary filleting and general thickening whenever needed. It is very dense once hardened. I also use the 403 on occasion because it can be mixed up to a thick consistancy a little quicker, but it does not smoothe out as well as the 404, And for some reason generates a lot of heat is not spread out pretty quickly. They offer 405 as a filleting filler, but I have never used it. If weight or easy sandability was an issue, I woudl look to the 407 or 410. Personally, I like to have several types of filler and experiment with them so I'll know their characteristics for future projects. Hope that helps.
I would buy this product again.
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.
Good strength for screw holes...
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.
404 High Density
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.
Excellent thickener for high-strength
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.
Vineland, New Jersey
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.
Butch Wood, Esq.
Transom and stringer replacement
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.
The strongest of the epoxy fillers
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.