Comparison

Two-part epoxy vs Epoxy putty: which should you use?

Same chemistry, different format. Liquid epoxy bonds two surfaces; putty rebuilds a missing one.

The short answer

Liquid epoxy to join two parts along a bond line. Putty to fill a hole, rebuild a broken corner or make a repair you can shape and sand.

Side by side

	Two-part epoxy	Epoxy putty
Strength	Structural	High
Flexibility	Rigid	Rigid
Gap filling	Medium	High
Water resistance	Water resistant	Water resistant
UV resistance	Poor	Moderate
How it cures	Chemical reaction	Chemical reaction
Clarity	Varies	Opaque
Typical working time	5 minutes to 2 hours	3 to 15 minutes
Typical full cure	24 hours to 7 days	1 to 24 hours
Maximum temperature	100C	120C
Needs clamping	Yes	No
Two part	Yes	Yes
Removable later	No	No

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 Two-part epoxy when

You are bonding, not filling. The two faces meet. You want the strongest possible joint along that line, and you can clamp it.

Choose Epoxy putty when

There is material missing. You need to shape the repair by hand, wrap it around a pipe, or sand and paint it afterwards. You need it to stay where you put it on a vertical surface.

What actually separates them

Putty is epoxy loaded with filler until it will hold a shape. That makes it brilliant at rebuilding and mediocre as an adhesive: the filler that stops it sagging also stops it wetting out a surface properly. Do not use putty where a liquid epoxy would fit.

Two-part epoxy

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

Epoxy putty