Fuel-resistant channel sealant. Dow DOWSIL Q4-2805 Fluorosilicone Sealant White is a one-part, fuel- and oil-resistant compound. It is easily injected and reinjected, non-curing, has good tack adhesion, and contains no catalyst or curing agent. It is used as a groove injection (channel) sealant for aircraft fuel tanks.
Why fluorosilicone. Fluorosilicone chemistry gives the sealant superior sealing characteristics under exposure to fuels and oils, where standard silicones would degrade or swell. Distributor data indicates it withstands immersion in fuels and exposure to fuel vapors at temperatures up to +200°C, and it is characterized across a broad temperature range.
Non-curing behavior. Because Q4-2805 is non-curing and contains no catalyst or curing agent, it remains workable and can be injected and reinjected into channels rather than setting hard. This makes it well suited to sealing applications that specifically require a no-cure sealant that can be reworked.
Application notes. Dow's channel-sealing guidance notes that the sealant should not be injected beyond the next port because back pressure develops, and forcing it further along the channel takes disproportionately longer. The product is supplied in a cartridge that plunges out the large end. Review the product and Safety Data Sheets before use.
Recommended For
Groove/channel injection sealing of aircraft fuel tanks
Sealing applications exposed to fuels and oils
Applications requiring a non-curing, reworkable sealant
Resistance: Fuel- and oil-resistant; withstands fuel vapors to +200°C (distributor data)
Application: Injected and reinjected; plunges out the large end of the cartridge
Container size: 212 g cartridge
Primary Industries
Aerospace and defense
Aircraft fuel-system manufacturing and maintenance
Industrial fuel and oil sealing
Standards and Certifications
None specified by source (OEM specifications may apply for aerospace use)
FAQs
What is DOWSIL Q4-2805 used for?
It is a one-part fluorosilicone channel sealant used primarily as a groove-injection sealant for aircraft fuel tanks. Its fuel and oil resistance and non-curing nature make it suitable for sealing applications exposed to fuels and vapors, where a reworkable, no-cure sealant is needed rather than one that sets hard.
Why is fluorosilicone used instead of standard silicone?
Fluorosilicone resists fuels and oils far better than standard silicone, which can swell or degrade on contact with hydrocarbons. That resistance gives Q4-2805 superior sealing performance in fuel-system environments, and distributor data indicates it withstands fuel immersion and vapor exposure at temperatures up to +200°C.
What does 'non-curing' mean for this sealant?
Q4-2805 contains no catalyst or curing agent and does not cure to a hard solid, so it stays workable. It can be injected and later reinjected into channels, which suits applications that specifically call for a no-cure sealant that can be reworked or topped up rather than permanently set.
How should it be injected into a channel?
Dow's guidance notes the sealant should not be injected beyond the next port, because back pressure builds up and forcing it further along a channel takes disproportionately longer. Following the recommended port-by-port method helps achieve a proper seal. Always consult the technical data sheet for the correct procedure.
Is any special certification needed for aerospace use?
The product is used in aircraft fuel tanks, and some distributors note that specific Manufacturer Part Numbers tie to particular OEM specifications. Standard manufacturer certification is not always available by default, so aerospace users should confirm the exact specification and documentation their program requires before purchase.
