The benefits and drawbacks of using Polyester

By Tony Wilson

The benefits and drawbacks to using a polyester coating 

Polyester coatings are the most commonly used method for wood finishings in furniture and interiors when trying to achieve a high gloss finish. Comprising of lacquer, activator, catalyst and a thinner. Polyester coatings can increase the durability of wood and add an attractive finish. If you’re looking for a finish with no imperfections and without covering the natural beauty of the wood then polyesters are a great choice. Clear/pinkish in colour, polyester allows you to fill and protect the grain whilst still being able to see the definition through the coating. Looking for colour? There are certain polyester pigments provided by specialist companies that can be used to achieve RAL or BS colours.

Wax or wax-free – what’s the difference?

Most polyester coatings are either made using wax or are made to be wax free:

Wax Polyesters 

PF6355 for example Mix Ratio

PF6355 (Polyester) 100 Parts

PH888 (Activator) 2%

PH999 (Catalyst) 2%

DX1131 (Thinner) 5-10%

Wax polyesters have excellent chemical stability, high filling capacity and high resistance to shrinkage. They often use a wet-on-wet application system which involves applying the next coat as soon as the previous coat has gelled. One huge benefit to this method is that the wax floats to the surface bringing any debris with it, these imperfections can then simply be sanded away with a Linisher (pad sander) or flatbed sander once fully cured normally 3-5 days. Once sanded, best practice would be to go up through the grits to P2000 or P3000 before then polishing to full gloss, or after sanding you may choose to overcoat with a matt lacquer.

The temperature of the polyester should be kept above 18-20 degrees at all times

We recommend the Sayerlack Thixotropic Wax Polyester Lacquer.

Wax Free Polyesters

PU1317 (Polyester) 100 Parts

PH888 (Activator) 1-2%

PH999 (Catalyst) 2%

DP0695 (Thinner) 20%

We recommend the Sayerlack Extra Clear Flexible Polyester Basecoat which has a high build, excellent transparency and can be buffed after hardening normally 3-5 days.

The temperature of the polyester should be kept above 18-20 degrees at all times

Furniture makers and sprayers can also choose to use a combination of: 

Polyester Basecoats

Polyester Clear Topcoats

Polyester Primers

The drawbacks to using polyester coatings

As with anything, polyester coatings won’t be perfect for every job. Here are some of the drawbacks that could affect the coating you choose for your next job.

  1. Shorter pot life – polyester coatings generally have a shorter pot life than most coatings. Once mixed up, this can be as short as 10-30 minutes making it unsuitable for certain jobs unless using a Plural Pump
  2. You may need a barrier coating – in cases where you want to overcoat a stain or a potential resinous timber you may require a barrier coat. Refer to the Technical Data sheet to be sure.
  3. Polyester can be a fire hazard if not disposed of correctly – When preparing a polyester coating, most people add the catalyst and activator using a pipette or syringe. It’s vitally important that they are kept separately (similarly any spillages must be disposed of using separate cloths). Combining the two can lead to cloths or syringes posing as fire hazards.
How to mix polyester

It’s important when mixing a polyester that you remember to stir it 4 times:

  1. Stir the polyester and weigh out the amount required
  2. Add 1-2% of PH888 depending on which polyester you are using and stir well
  3. Then add 2% of PH999 and stir well again
  4. Finally, add your thinners and stir well for the final time
The final word

No product will be 100% suitable for every type of project and polyester coating is no exception but if you’re looking to add durability,  and a full gloss finish to the wood you’re working with then it’s not to be overlooked.

We now also stock a fantastic Polyester product from another quality Italian brand – Milesi Wood Coatings.

Get in touch with us to learn more 01452 525757, or fill out the form below.

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