Comparison

MS polymer vs Silicone sealant: which should you use?

Both flex and both survive water. One is an adhesive that seals, the other a sealant that barely sticks.

The short answer

MS polymer whenever the joint has to hold something. Silicone when it only has to keep water out, or when the joint is glass or sanitary ware and you need it to stay flexible forever.

Side by side

	MS polymer	Silicone sealant
Strength	High	Medium
Flexibility	Flexible	Very flexible
Gap filling	High	High
Water resistance	Water resistant	Waterproof
UV resistance	Good	Good
How it cures	Moisture cure	Moisture cure
Clarity	Varies	Varies
Typical working time	5 to 30 minutes	5 to 20 minutes
Typical full cure	2 to 7 days	Several days, depth dependent
Maximum temperature	90C	200C
Needs clamping	No	No
Two part	No	No
Removable later	No	Yes

Highlighted rows are where the two genuinely differ. These describe the families in general, not any particular product, so check the datasheet of whatever you buy.

Choose MS polymer when

The bond carries any load at all. You want to paint over it. You are bonding to a porous surface, or to something you will want to remove one day without destroying it.

Choose Silicone sealant when

Pure sealing: baths, showers, glazing, around a sink. Constant water contact or immersion. Temperatures that would soften other sealants. Where nothing needs to be held, only sealed.

What actually separates them

Silicone has excellent movement capability and almost no adhesive strength, and nothing will paint over it or stick to it afterwards, including more silicone. MS polymer is genuinely structural in a way silicone is not, and stays paintable. If you are choosing between them for a job that holds weight, it is not a real choice.

MS polymer

The full guide: what it is for, where it fails, and which materials it suits.

Silicone sealant