A better way to apply polyurethane to SOF kayaks

Most kayak builders who have used the 2 part urethane coating from Corey’s Skin Boat Store have a love-hate relationship with it. The first coat goes on well enough and is very durable but it leaves a lot to be desired as a finish coat. After years of frustration I tried something different.

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This Curlew Baidarka is my second qayaq primed with Corey’s Goop and finished with a marine polyurethane paint.

 

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RavenWoods Tulugaaq Rolling Qajaq with Corey’s Goop for primer and Brightside polyurethane marine paint for the finish. A flattening agent was used to create a matte finish.

 

Many painting/coating systems have a primer and a finish coat. The qualities that make good primers and finishing coats are very different. A primer needs to adhere well and make a firm base for the finish coat. The finish coat needs to cure fast and come in a wide variety of colours including clear. Finish coats should provide a choice of glossy or matte. Finish coats look better if applied with a roller and have a textured finish. Finish coats should avoid drips and curtain sag.

It occurred to me that Corey’s goop had all the qualities of a good primer and none of the qualities of a good finishing material. Marine polyurethane paints formulated for million dollar yachts have all the qualities of good finishing coatings. Why not use two different products that match the requirements for each job? I made a frame and stapled scraps of ballistic nylon to it and tried a number of different treatments including:

1/ 3 coats of Corey’s goop
2/ 3 coats of System Three clear satin polyurethane marine paint
3/ 3 coats of Dura-Tuff
4/ 1 coat of Corey’s goop and 2 coats of System Three clear satin polyurethane marine paint.

Corey’s goop produced the typical shiny finish. The System Three by itself did not saturate the fabric, did not load as much polyurethane into the nylon and produced a crinkly finish. The Dura-Tuff treatment was acceptable even if it was a bit crinkly. Dura-Tuff is formulated with toxic solvents that are dangerous to breathe. The combination of Corey’s goop and System Three worked perfectly. Corey’s goop saturated the nylon with lots of polyurethane and produced the colour coat with a rare earth dye. The System Three produced a lovely textured, satin, translucent coat. The texture softened the appearance.

The combination of Corey’s goop and marine polyurethane paint works very well for a number of reasons:
– Corey’s goop saturates the fabric and encases the nylon fibres
– Rare earth dyes can be used with Corey’s goop to supply the colour
– Water soluble acid dyes can be used before Corey’s goop is applied
– Drips and curtain sags can be avoided with Corey’s goop on the first coat by scraping for an hour and doing drip checks for another hour. Big drips can be cut off or sanded.
– About half a container of Corey’s goop is required for 1 generous coat over an entire kayak
– Only use uncoloured polyurethane on the inside of the combing to avoid drips
– There is a wide choice of excellent one part polyurethane satin marine paints. They are available in both clear and coloured paint.
– I suggest that the marine paint be applied within 12 hours of applying the Corey’s goop to ensure good adhesion. Try a test sample first.

I have coated four kayaks with this combination. Marine polyurethane paint is very flexible. I know of several kayaks on Vancouver Island that have been treated with single part marine polyurethane. They are flexible and have worn well over the last 5 years except for a little crackling in the finish. The problem with using single part marine polyurethane by itself is that it sits close to the surface and does not saturate the fabric like Corey’s goop does. A good finish coat requires a good primer coat. If you scrape the finish on a rock, just clean it, sand it and apply another finish coat.

Marine polyurethane coatings are available from Interlux,  Pettit  and System Three.

Corey’s Goop is available from http://www.skinboats.org/

If you try this combination and like it please provide some feedback.

 

 

 

 

 

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