Powder Coating Resin Change: Can the Original Additives Still Be Used?- Suzhou Qingtian New Material Co., Ltd.

Powder Coating Resin Change: Can the Original Additives Still Be Used?

2026/09/24

When a powder coating changes resin, the existing additives do not necessarily all need replacing, but the old formulation should not be copied across directly. Changes in the resin's acid value, melt viscosity, softening point and curing system all affect how additives work. After a resin change, leveling, gloss, degassing and storage behavior need to be observed again.

Introduction

Resin is often an important variable when a powder coating formulation is adjusted. After changing the resin, some companies keep using the original leveling agent, degassing agent or other additives, yet the film that comes out of production changes.

For example, a surface that used to be fairly smooth shows texture, the gloss changes, or the stored powder is in a different state from before.

This shows that an additive does not perform apart from the resin system.

Why additive performance changes after a resin change

During melting and curing of a powder coating, the resin's melt viscosity, softening characteristics and curing reaction all influence film formation.

For example, if the flow of the molten resin changes, an additive that used to meet the leveling requirement may act differently in the new resin system. Changes in the resin's acid value, hydroxyl value, glass transition temperature and similar parameters may further affect the interaction between additive and system.

So a changed surface after a resin change does not necessarily mean the original additive has "failed"; the whole formulation environment may have changed.

What affects the leveling agent

A leveling agent mainly takes part in surface flow and spreading after the powder melts.

If the melt viscosity of the new resin differs from that of the original system, the time and extent to which the film can flow in the melting stage also change.

In that case, even if the leveling agent type and dosage stay the same, the final film flatness, gloss and surface texture may differ. After a resin change, therefore, do not look at the leveling agent alone; judge it within the whole melt-leveling process.

Do degassing and other additives need another look?

Yes. A powder coating goes through air release, melt spreading and curing. If the resin system changes, the melting state and the way gas escapes may change too.

A degassing system that used to be suitable may show bubbles and similar surface changes after the resin is changed.

In addition, matting agents, texture additives and wax powders also have a formulation match with the resin, so do not adjust only the leveling agent and ignore the other components.

How to judge after a resin change

The more suitable way is to keep the original additive system first and make a small batch with the new resin.

If the basic performance has already changed, run gradient tests on individual additives. For example, set several dosages of leveling agent and observe gloss, surface flatness and texture; for the degassing system, compare bubbles and similar conditions.

This shows whether the problem comes from the resin itself or from a changed match between the original additives and the new resin.

Can the original additives still be used?

The answer is: possibly, but it must be verified again.

If the melting characteristics, curing system and formulation environment of the old and new resins are fairly close, the original additives may still work and only the dosage needs adjusting. If the resin changes a lot, the additive type has to be screened again.

So a resin change does not mean every original additive must be replaced. A more reasonable approach is to keep the original scheme as a control and adjust item by item according to the actual film performance.

Closing remarks

In a powder coating, resin and additives are not independent of each other. After the resin's melt viscosity, acid value, softening characteristics or curing conditions change, leveling, degassing and the final surface may all be affected.

So after a resin change, the original additives can serve as the starting point of the new formulation, but it is not advisable to assume the original formulation will certainly apply.

Only by comparing the old and new resins and testing leveling, gloss, degassing and storage state can one tell whether the original additives need replacing or adjusting.

Questions Formulators Often Ask

Do all additives have to be replaced after a resin change?

Not necessarily. The original additives do not all need replacing, but the original formulation should not be copied across directly.

Why can the surface change even though the additive was not changed?

The resin's melt viscosity, softening characteristics, acid value, hydroxyl value, glass transition temperature and curing reaction affect film formation, so the whole formulation environment changes, not necessarily the additive itself.

How should the original additives be checked on the new resin?

Keep the original additive system, make a small batch with the new resin, and if basic performance has changed, run gradient tests on individual additives, such as several leveling agent dosages or a bubble comparison for the degassing system.

When can the original additives continue to be used?

If the melting characteristics, curing system and formulation environment of the old and new resins are fairly close, they may still work with only the dosage adjusted; if the resin changes a lot, the additive type has to be screened again.

Summary: after a resin change the original additives are a starting point and a control, not a guarantee. Compare old and new resin and test leveling, gloss, degassing and storage state before deciding whether to keep, adjust or replace them.