|  First Published: December 2011

I really can’t believe another year has flown by and for me personally it was a crazy year. It was also my first year writing for QFM and hopefully the first of many.

This issue is the second part of my section on boat repair products. This part will cover gelcoat, flowcoat and catalyst.


We use gelcoat because it provides a high quality finish and is normally applied into a mould. However, it can also be used to touch up cracks or chips, which is commonly known as a gel repair. It’s in a liquid form and as with polyester resins, it requires a hardener or catalyst for it to set, or in scientific terms it’s called polymerisation. I will cover this more in the catalyst section.

Gelcoat is very robust, providing resistance to UV rays and is pigmented in different colours. Personally I think gelcoat should never be overlooked as this will protect your whole boat. If you do the simplest tasks using gelcoat from new it will stay new forever, but if you crack it and water or moisture can get in, it’ll be the beginning of the end if you don’t attend to it quickly. So if something is cracked or damaged in a spot prone to water exposure deal with it asap. Get advice or help from a friend with the knowledge – leave it too long it’s going to hurt the hip pocket.

When gelcoat is applied we also add an additive called wax and styrene. This stops the gelcoat from being sticky when you sand it. It can also work as a slight thinning agent as spraying can be difficult if you don’t have the right consistency. Getting this right will come with experience and trial and error. Doing a few sample pots on a flat sheet to get your spray adjustments and pressure sorted will help the cause.


Flowcoat is going to be a little easier to explain as it’s similar to gelcoat, but when you use flowcoat all you need to do is add a catalyst and it can be applied as long as all the surfaces are prepped correctly beforehand. Flowcoat involves a few more processes in its manufacture than gelcoat but is more easily applied by rolling or brushing it on. It leaves a long lasting, durable finish.

Flowcoat is a lot thicker than gelcoat and is used by both the retail and commercial sectors as it conceals a lot of little defects. Being so thick it can be used on sharp corners or vertical walls and the finish looks great. Flowcoat’s viscosity means it’s very much an essential element.

Both gelcoat and flowcoat will need a hardener added for it to cure also known as catalyst. Flowcoat will definitely get hotter in the cure stage as it’s thicker.


Catalyst is actually short for Methol Ethol Keytone Peroxide and with the complex name comes a large risk when handling the chemical. I can’t stress enough how much care needs to be taken when using catalyst, so make sure at the very minimum you have your safety’s on before de-caning, moving or mixing catalyst. If you get this in your eyes you have 15 minutes tops before you could have permanent sight damage. When mixing in the pot, stir slowly and around the outside edge to minimise the risk of spillage.

Catalyst is what creates the polymerisation stage, bringing it from a liquid to a hardened form. When the polymer chains in the poly based product meet the catalyst they all lock up together causing a heating process. Remember to not over catalyse your mixes in both gelcoat and flowcoat. It could even get hot enough to start a fire. Use the ratio of 10ml of catalyst to 1000ml of gelcoat or flowcoat. The rule of thumb is don’t be afraid to seek advice from someone with the knowledge and experience in using these products before going it alone.

Over catalysing can also cause a couple of dramas with the finish. One being porosity and the other being heat print. These are conditions that can be avoided by sticking to the plan and having your ratios correct. These products are also quite expensive so getting it right first time will also avoid pain in your hip-pocket.

Happy new year and all the best for 2012.

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