Chemical resistance, and the parts you forget

What actually touches the product

The bottle wall, the dip tube, the gasket, the piston or valve, the spring in older designs, and the nozzle. A solvent or a silicone that the bottle shrugs off can swell a gasket or seize a piston within weeks.

Solvents are the usual culprit

Even at the reduced levels VOC limits allow, a formula can carry enough solvent to attack a seal over months on a shelf. The failure is slow, which means it reaches customers rather than showing up in testing.

Silicones are their own problem

Tire dressings and trim products are frequently silicone-based and they behave differently from aqueous cleaners in a sprayer: viscosity, wetting and residue in the nozzle all change. A sprayer chosen for a glass cleaner may not suit a dressing.

Metal springs rust

A sprayer with an exposed metal spring in an aqueous product can corrode, which contaminates the product and eventually jams the trigger. All-plastic designs exist for this reason and are worth specifying where the formula is water-based.

The data sheet tells you what to avoid

Section 7 of the safety data sheet covers handling and storage and will flag materials that are unsuitable. That is a faster route than testing every candidate, and it narrows the field before the physical check.

Then test it for weeks, not minutes

Fill the real sprayer with the real formula, use it, and leave it standing for a month before deciding it works. Chemical attack is a slow failure and a same-day test proves nothing about it.

Ask the sprayer supplier, in writing

They test against common formulations and will usually say what a component is and is not suited to. That answer, kept with your formula record, is worth more than a compatibility chart written for pure solvents your product only partly resembles.

References