Industrial Sealants: what Claude and GPT would buy
Two AI models chose on their own, with no web access. Nobody tested these products: this is what each one says, and how to check it.
Claude and GPT choose the same line: DOWSIL
In Industrial & Scientific, Claude and GPT choose the same brand in 52 of 107 categories.
Claude Opus 5.5 · October 28, 2026
DOWSIL 795 Silicone Building Sealant
A neutral-cure, high-movement silicone with a long track record that bonds to glass, metal, coated and many masonry substrates and holds up to UV and weather far longer than general-purpose caulks.
Not for: Anyone who needs to paint over the joint, seal pipe threads or flanges, or seal traffic-bearing horizontal joints.
GPT 6.1 Sol · November 10, 2026
Dow DOWSIL 732 Multi-Purpose Sealant
Versatile silicone sealant providing durable, flexible seals and strong adhesion to many nonporous industrial surfaces.
Not for: Paintable joints, structural bonding, or corrosion-sensitive electronics.
Which one fits you
rigid machined flange gasketing
Loctite 518
An anaerobic gasket maker that cures only between close-fitting metal flanges, so excess stays uncured and wipes off.
Not for: Stamped sheet-metal covers with large or flexing gaps, which need an RTV silicone instead.
permanent marine-grade bond and seal
3M Marine Adhesive Sealant 5200
A polyurethane that seals and bonds permanently above and below the waterline.
Not for: Any part you will ever need to take apart.
high-temperature engine and equipment gaskets
Permatex Ultra Copper (line)
A sensor-safe RTV silicone formulated for the high-heat end of formed-in-place gasketing.
Not for: Fuel-wetted joints or precision flanges better served by an anaerobic.
Check before you buy
Where to find DOWSIL 795 Silicone Building Sealant
- Global Industrial
- ESCO Products
Shops seen in search results on November 5, 2026. A shop missing here may sell it too. Nothing was checked by a person.
Brands that matter
- DOWSIL: Dow's silicone line, a long-standing standard for building and industrial silicones.
- Sika: Sikaflex polyurethane and hybrid sealants are widely specified for construction joints.
- Loctite: Henkel's anaerobic thread sealants, flange sealants and RTVs for machinery.
- 3M: Known for marine and industrial polyurethane and hybrid adhesive sealants.
- Permatex: RTV gasket makers and thread sealants aimed at automotive and equipment maintenance.
- Tremco: Commercial construction sealants such as the Vulkem polyurethanes.
- Pecora: Commercial silicone and urethane joint sealants for building envelopes.
What to avoid
- Acetoxy (vinegar-smelling) silicone on bare metal, concrete or near electronics.
- Painting over silicone; paint will not adhere.
- Using a permanent polyurethane adhesive sealant on parts that must come apart later.
- Sealants past their shelf life, which may cure poorly or not at all.
Questions
Is a sealant the same as an adhesive?
No. Sealants are designed to fill gaps and stay flexible. Some adhesive sealants also bond strongly, which makes them hard to remove later.