Lightweight Polyester Cosmetic Filler
Details
Details
High Quality No-Shrink Surface Filler
Lightweight Polyester Cosmetic Filler is a versatile, creamy paste designed to fill, seal, repair, and finish surface damage on composite materials. When applied, it quickly forms an exceptionally rigid and strong surface which can easily be sanded to a feather edge. It will not shrink, sag, or pin-hole after curing, and it can accept virtually any paint or finish without any special surface preparation. This thixotropic filler delivers excellent physical and cosmetic properties.
Apply catalyzed #4116 Lightweight Polyester Cosmetic Filler with a spatula or putty knife. After 15-20 minutes, it can be sanded to final finish.
What Is #4116 Lightweight Polyester Cosmetic Filler?
#4116 Lightweight Polyester Cosmetic Filler is a versatile, creamy paste designed to fill, seal, repair, and finish surface damage on composite materials. When applied, #4116 quickly forms an exceptionally rigid, strong surface that can be sanded to a feather edge. The thixotropic formulation of #4116 delivers excellent physical and cosmetic properties without shrinking, sagging, or pinholes after curing.
Why Choose #4116 Lightweight Polyester Cosmetic Filler?
The standout property of #4116 Lightweight Polyester Cosmetic Filler is its finish behavior: it will not shrink, sag, or pinhole after curing, and it accepts virtually any paint or finish without special surface preparation.
When cured, #4116 adheres to a wide range of substrates including fiberglass, SMC, RIM, BMC, plaster, graphite, KEVLAR, steel, iron, and copper. For structural rebuilding of broken or voided areas, the fibrous #4100 Polyester Fairing Compound is used first, with #4116 applied over it for the cosmetic surface.
What Are the Best Applications for #4116 Lightweight Polyester Cosmetic Filler?
#4116 Lightweight Polyester Cosmetic Filler is the right choice for automotive finishing, filling surface porosity, and repairs on bass boat hulls, composites, vacuum molds, tub and bath applications, urethane molds and parts, and cracks, dents, and crevices on worn surfaces.
It is the cosmetic finishing filler. Pair it with #4100 Polyester Fairing Compound when the repair must be rebuilt structurally first.
How Should #4116 Lightweight Polyester Cosmetic Filler Be Used for Best Results?
#4116 Lightweight Polyester Cosmetic Filler is catalyzed with BPO hardener at 100R:2H parts by weight, then applied with a spatula or putty knife. Working time is about 5 minutes on a 100 gram mass, and after 15 to 20 minutes it can be sanded to a final finish. For structural repairs, rebuild first with #4100 Polyester Fairing Compound and apply #4116 over the cured repair.
Technical Specifications
• Type: Thixotropic lightweight polyester cosmetic filler, off-white
• Hardener: BPO, 100R:2H by weight
• Working time (100 gram mass): 5 plus or minus 1 minutes
• Finish schedule (100 gram mass): 15 minutes
• Will not shrink, sag, or pinhole; accepts most paints and finishes
Available Sizes and SKUs
• #4116-A — Quart
• #4116-B — Gallon
• #4116/266-A — Quart kit with 1 oz BPO hardener tube
• #4116/266-B — Gallon kit with 4 oz BPO hardener tube
Every product Fibre Glast sells is First Quality Guaranteed, so you can finish surfaces smooth with confidence.
- Resin Color – Off-White
- Working Time (100 gram mass) – 5 ± 1 minutes
- Finish Schedule (100 gram mass) – 15 minutes
Requires BPO Hardener – 100R:2H (parts by weight).
Shipping
Shipping
Sizes
Sizes
WARNING: This product can expose you to chemicals including Styrene & Titanium Dioxide (airborne, unbound particles of respirable size), which are known to the State of California to cause cancer. For more information go to www.P65Warnings.ca.gov

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Excellent qualities, easy to work with and provides an excellent surface for painting
This stuff is great and a little goes a long way. Being a novice at best on my 1st boat Resto/Gelcoat the team at Fibreglast have been awesome in recommending what is needed to get this done. The fairing compound is simple and a little goes along way. As with other filler putty use it sparingly and build it up in thin layers sanding between layers. I am waiting for my 2nd order of materials from Fibreglast of the various Gelcoat Additives and hopefully after the 1st of the year I will be ordering 5 gallons of Clear Gel. a gallon of Burnt Orange to have on hand when the weather warms up. Karsten
This is my second quart (3 pound) can of 4116. My experience with the first can started poorly, but ended up fine. I've seen plenty of videos where people scoop out some filler and add some BPO hardener, but most of the time I couldn't estimate correct amounts of each, and I ended up with a sticky result. Or, maybe I wasn't getting it mixed well (although I mixed it a lot).At some point the BPO tube broke while I was kneading it before using it. I almost discarded the remaining filler because I was usually frustrated with the result anyway; instead I ordered a tube of black BPO. I also bought a Taylor digital scale that measures up to 454 grams (or 16 ounces). (Found the scale in the kitchen department of my local discount department store for about $13.)Using the scale and dark hardener gave me consistent results. I can accurately get the required 50:1 ratio of filler to hardener and I can be sure the two are well mixed. Just weigh the amount of filler you want (use grams for better resolution), divide that by 50 to determine how many grams of BPO to add, then mix.The result is light grey and covers fine with white gel coat. Most times I wish it wouldn't cure quite so fast but that's usually only a problem on smaller parts where you're trying to get a detailed shape right. Wide open, flat areas aren't usually a problem.
Great ! Lightweight , fills in void and bonds great, sands respectfully easy for what it is and paints over smooth