Neutral vs Acidic Cure Silicone: Which One for Your Project
Silicone sealants cure in two fundamentally different ways — acidic and neutral. Choosing wrong can corrode your materials, void warranties, and cause premature failure. Here is how to decide. In practice, the 793 neutral silicone weather-resistant adhesive and 388 acid silicone weatherproof adhesive show the two cure chemistries side by side.
1. Acidic Cure: Fast, Cheap, and Dangerous on Metal
Acidic (acetic) silicone cures by releasing vinegar-like acetic acid. It bonds fast and is excellent on glass, ceramics, and smooth non-metal surfaces — which is why it dominates bathroom and mirror applications. But that acid attacks metal. On aluminum frames, galvanized steel, and even some coated surfaces, acidic silicone causes corrosion that shows up months later.
2. Neutral Cure: Safe on Everything
Neutral-cure silicone (oxime or alkoxy based) releases harmless byproducts. It is the only safe choice for coated aluminum, stainless steel, copper, and most construction metals. That is why structural and curtain wall sealants are always neutral cure — GB 16776-2005 structural grades are neutral by definition.
3. The Corrosion Test That Decides
If you are unsure, run a simple corrosion coupon test: apply both sealants to your actual substrate, cure, and check after 30 days. Acidic silicone leaves visible corrosion on metal; neutral stays clean. Laboratories run accelerated versions of this test for every serious project.
4. Where Each One Wins
Use acidic silicone for: glass-to-glass, bathroom, kitchen, aquariums, and other metal-free joints. Use neutral for: curtain walls, aluminum and steel frames, coated panels, electronics, and anywhere corrosion risk exists. When in doubt, choose neutral — the cost difference is small, the failure cost is not.
5. For Distributors
Stock both grades but label them clearly. Contractor misuse of acidic silicone on metal frames is one of the most common warranty disputes in the industry. A distributor that prevents this mistake builds lasting trust.
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Related guides: Silicone vs MS Polymer Sealant: which chemistry fits your project
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