| so long as the tube is unused it should be ok... the active ingredient is the solvent, usually a MEK style solvent, this will if left open slowly evapourate away....
my recomendation is get some new cement or even some plasweld instead......
if you really cant bring yourself to throw this away do a test to see how effective the cement still is.... break off two parts of sprue ( the frame that holds the model parts) and bond them together with the cement.... you will then be able to see if its any good...... |