Please select your home edition
Edition
SW newsletters (top)

421 Fire Retardant Additive for West System Epoxy Resin

by Jake Kavanagh 1 Aug 04:00 PDT
421 Fire Retardant Additive for West System Epoxy Resin © Wessex Resins & Adhesives

What is it? WEST SYSTEM® 421 Fire Retardant Additive does what it says on the tin - it retards fire. It is a heavy, non-combustible powder that is added to a fresh mix of epoxy.

Used for? An extra layer of fire protection in areas such as galleys and engine rooms, or anywhere there may be a risk of heat absorption that could lead to combustion, including cabins and saloons. It could also be used to line the coffer dams around skin fittings to prevent hoses being burnt through, or to run on partitions beside hot areas such as exhausts. It is especially useful if the partitions themselves are combustible, such as plywood bulkheads or galley headliners.

Mixing ratio: An easy 1:1 by weight. However, at this ratio the additive will greatly increase the viscosity of the epoxy so the resulting mix will need to be applied with a trowel or squeegee.

Hamish's Tips

"This is a very straightforward additive, so just follow the mixing ratio and be prepared to apply a thick layer of material," Hamish says.

"It will help to apply a coat of epoxy onto a properly prepared (degreased and abraded) substrate first to achieve better adhesion. When tacky, apply the epoxy/421 Fire Retardant Additive mix over the top. If you want to apply further layers of sound-proofing to the partition use peel ply during the application or wash the cured 421 Fire Retardant Additive down to remove the amine blush before sanding.

"Key the surface to promote good adhesion of the soundproofing, although peel ply does that automatically on removal. That's it - 421 Fire Retardant Additive will give additional peace of mind in areas of the hull with a higher risk of fire."

Typical application

We wanted to enclose the engine wet exhaust that runs along the floor between two bunks, so needed a plywood partition. To fireproof the plywood beneath the soundproofing, we decided to treat it with a coat of 421 Fire Retardant Additive.

Related Articles

Wessex Resins and Adhesives announces line-up
Guest speakers for Southampton International Boat Show Wessex Resins and Adhesives has announced the line-up of guest speakers for its 'in conversation with' day at Southampton International Boat Show 2019. Posted on 4 Sep
Building an 18th century Gajeta part 8
Finishing touches made to old design built with modern epoxy In our latest instalment of the building of a replica of an 18th century Croatian Gajeta, ‘Lipa Moja' becomes the sum of her parts. Many hours of craftsmanship have resulted in a beautiful vessel that is ready to race. Posted on 27 Aug
How to burst bubbles in epoxy
Simple tricks, and what to watch out for If you're finding that you've got bubbles when pouring clear casting epoxy here are some simple techniques to help resolve the problem. Posted on 21 Aug
Building an 18th century Gajeta part 7
Modern epoxy techniques on a classic design After several months of intense boatbuilding, the craftsmen at the Betina Shipyard in Croatia are in the final stages of the completing their experimental 7-metre traditional sailing gajeta. Posted on 29 Jul
Happy Birthday to Gougeon Brothers, Inc
Creators of West System epoxy celebrate 50 years Wessex Resins & Adhesives manufacture WEST SYSTEM®, PRO-SET® and ENTROPY RESINS® under licence from the Gougeon Brothers Inc, USA. Below Grace Ombry traces the company's heritage, from its modest beginnings as a boat shop... Posted on 5 Jul
Tips from the Epoxy Professionals
Preparing teak strips for bonding Here's a tip for preparing a teak plank for a small-scale project such as a cockpit table. It could work just as well on a complete deck. Mark at Aquamarine Ltd uses it whenever he wants to bond teak to a substrate (no screws). Posted on 2 Jun
Making a Mouse Boat with Oarsome Chance
Disadvantaged boat-building students use just one sheet of plywood Wessex Resins and Adhesives is a proud sponsor of the charity Oarsome Chance, where disadvantaged and school-excluded young adults learn how to build and repair boats and use them on the water. Instructor Nick Hart describes the making of a 'Mouse Boat'. Posted on 31 May
Raising the bar with Entropy Resins
A sailing club bar top with a nautical theme James Case has been a member of Wells Sailing Club since he was a child. "It's always had the same bar," he says, "but when the club decided to do a major refit, we decided to make a new bar with a nautical theme." Posted on 28 May
Bio-based epoxy resin now available in Europe
Manufacturers of West System epoxy now sell Entropy Resins too Wessex Resins & Adhesives is delighted to announce the launch of a new online store to facilitate ordering the unique range of bio-based epoxy: ENTROPY RESINS. The EU online store has been added to the current North American website. Posted on 19 May
MBW newsletters (top)