Application of Coelan

I have been looking forward to trying to work with Coelan. I’ve heard so many different rumors, both positive and negative, so the thought of the process, I was about to start, almost made me nervous.

Let me state right away that you can forget about throwing away the sandpaper, at least if you want it to look nice. Coelan is not a varnish and the application of it is significantly different. It is a very thick substance and it must be diluted extensively in order to obtain a reasonably smooth result, but more on that later. It's not that difficult to work with, but it takes a crazy amount of Coelan to reach the recommended layer of 1 mm.

The primer

Coelan primer may look a bit like a wood-stain, but don't be fooled - it is polyurethane exactly as the clear, but much thinner and mixed with a UV protective color. It is very easy to apply, I used a brush and it was a breeze to get it even. But be careful on top of the black deck-caulking, especially with the yellow primer, just a little too much, then you have yellow or reddish joints. Remember to buy a few extra brushes, the primer has a strong tendency to build up flakes at the top of the brush, and it is virtually impossible to clean them.

Two coats of primer must be applied with a light sanding in between, and after the second time, the surface has a nice silky matt finish. The picture shows the wheelhouse roof after 2 coats of primer, I used the red primer for the Sapeli edges and the yellow primer for the Iroko deck.

The clear

As mentioned earlier, Coelan is very thick, and the instructions given by the manufacturer do not work well in practice. It takes a lot of diluting, a lot! For brush, I used 0,5 liter thinner for 1 liter Coelan. For the spray gun, I ended up with 1 liter thinner for 1 liter Coelan, which was a lot more thinner than I had ordered, so I had to order more in a hurry. I didn't use a roller, but I would think the same amount of thinner as for the spray gun will be right, maybe a bit less.

Because it is the layer thickness that is decisive for the durable result, it takes a lot of Coelan - I ended up using 30 liters. However, a lot is wasted when using a spray gun, which is probably the reason why I needed more than I had expected. I gave the vertical surfaces 14 coats, the horizontal 12 coats with the spray gun.

A problem with using a spray gun is the spray mist, which causes the horizontal surfaces to become dull, if you spray for a long time and don't have enough ventilation (I used proper protection). So I had to split it up and spray first the vertical surfaces, and then after it had dried properly, I masked it and sprayed the horizontal surfaces. The drying time is quite short, and if you do not have to walk on the surfaces, you can put on several layers in one day, but remember to remove insects and dirt before putting on the next layer. This is most easily done by sanding lightly with sandpaper grain 220. After a few coats, the stain will be gone.

Before the last 4 coats, the surface must be sanded thoroughly in order to get a smooth finish. Coelan tends to become a bit uneven, and it gets worse as you apply more layers. Use grain 100 to 120 to sand the surface, and if you are still within the 14 days where sanding can be omitted, finish with grain 220. You if you spray or use a roller, you need at least 4 coats afterward, otherwise there will be visible scratches, especially if you don't finish with grain 220. If you use a brush, 2 coats should be enough. And you have to wipe the surface very thoroughly after to remove abrasive dust - it is extremely difficult to avoid dirt on the surface, even if you are very careful.

And how does it look - quite nice actually. The finish is shiny and the thick layer gives it some depth, but it can in no way be compared to a good quality varnish such as Epiphanes and it is very difficult to obtain a 100% smooth finish, even with a spray gun. It may be a matter of experimenting with the dilution and of course practice. I think I have obtained a reasonably satisfactory result, and above all, my decks are now 100% waterproof.

The picture shows the foredeck after 12 coats.

I ended up using 30 liters of Coelan and just as much thinner. The result is really good and it looks like the durability is excellent. Contrary to what one might think, the surface is not slippery to walk on. I am extremely satisfied.

It turned out that it was fairly easy to apply with a brush, and it did not take so many layers to achieve sufficient layer thickness, only 5-6 layers. There are some brush stripes, but I think if I sand it and give it a couple of extra diluted layers, it will look just as nice as the sprayed parts.

The colored Coelan covers incredibly poorly, it takes many layers to cover dark colors. My roofs were white beforehand, but there were some dark spots after sanding and I had to spray 8 coats on to cover them.

A few good advices

Here are some tips to help you get started with Coelan

Do not attempt to walk on the surfaces after only 24 hours, as the instructions say. It is still sticky and fluff from your socks will stick to the surface where you step. I tried with plastic bags on my feet, which is better, but still leaves imprints. It is best to completely avoid stepping on it within the first 3 days.
Be very careful with the primer on top of the deck joints, otherwise, you will end up with red or yellow joints.
It is easiest to sand before it hardens too much, ie within the first 3 days.
Wipe the surface VERY thoroughly after sanding. The product is a bit sticky, therefore there is dust sticks the surface. Rub with a dry cloth until it feels smooth, and finally wipe the surface a few times with a resin cloth.