PCS Coating Application Techniques 3

Question 1

Plural-component spray equipment is mainly used for which type of coating?

Accepted Answer

Fast-setting, short pot-life materials such as polyureas and some 100% solids epoxies

Answer

Plural-component rigs meter and mix the components at or near the gun, so materials with very short pot life can be applied.

Question 2

During airless spraying, the fan pattern shows 'tails' (heavy stripes at the top and bottom edges). What is the most likely cause?

Accepted Answer

Fluid pressure too low or the material too viscous to atomize fully

Answer

Tails form when there is not enough pressure to atomize the material fully, which is usually low pressure or high viscosity.

Question 3

What is the purpose of the induction (sweat-in) time listed for some two-component epoxies?

Accepted Answer

To let the components start reacting before application for better cure and film properties

Answer

Induction time lets the resin and curing agent pre-react, which improves compatibility and helps prevent problems such as amine blush.

Question 4

What does using a mist coat (tack coat) before the full coat of a zinc-rich primer or over porous substrates help prevent?

Accepted Answer

Pinholing and bubbling from air displaced out of the porous surface

Answer

A thin mist coat lets air escape and seals the pores, so the following full coat does not pinhole or bubble.

Question 5

What usually happens when you add more thinner than the manufacturer's maximum recommendation?

Accepted Answer

Lower DFT per coat, risk of sags, and possible VOC noncompliance

Answer

Over-thinning reduces the solids that are applied, encourages runs and sags, and can exceed regulatory VOC limits.

PCS - Protective Coatings Specialist Certification Practice Test