Thread: Glue colour for paulownia timber

You don't want glue to fill nail holes and blemishes. Glue stops the timber absorbing epoxy and guarantees that it will be a different colour from the rest of the timber. Any glue residue left on the surface will cause the same problem.

If the nail holes are very small holes you created during the stripping process, try a damp cloth and a hot iron before you resort to filler. Unless the timber is badly crushed or torn, it is often surprising how well the holes close with a bit of steam.

If some of the blemishes are big splinters that have torn out, then often making the blemish into a V shaped groove that you can glue a sliver of timber into gives the least visible fix.

Some people mix wood dust with epoxy to create a filler, but that has problems. The wood dust absorbs epoxy like end grain, so will be a lot darker than the rest of the timber. There isn't much timber available that is paler than epoxy, so you have to resort to flour or talc to make it lighter. Then you have the problem that the epoxy/wood dust paste is considerably harder than the surrounding timber, so it takes more skill to avoid problems when sanding

If you do have to use filler, then common water based timber fillers will work. There are a few things that make getting a perfect match difficult. You won't be able to buy a filler that is a perfect match. There will be some variation in the colour of different parts of the timber. The timber will change colour when the epoxy is applied. The epoxy will also change the colour of the filler, but not the same change as the timber. The timber will change colour over time as it will be slightly affected by UV light, even with all the appropriate UV protective coatings.

If you have the need, the time and the persistence, then your best bet is to buy two or three colours and create the colour you want. You then need to create test patches on scraps of timber to learn how the filler and epoxy change when the epoxy is applied. If you are clever enough to get a perfect match, then in ten years time there will be a discernible difference.

BTW, I like the look of the Redfish kayaks. I hope that some time in the future, you will post photos of the finished kayak and that a bit later, you will post a few comments about your impressions of the performance of the kayak.

Welcome to the forum Richard. Must agree with Alan regarding the Redfish designs but if you have any progress photos I'd be interested in seeing them now as well as the finished product later.

With regard to filler I would just add that if I was building another stripper now I would not fill the nail holes unless absolutely necessary. If you must fill and can't get a good colour match then a filler that is darker than the timber seems to look better than the other way around. This may just be my personal preference but somehow it seems more natural.

Finally, if you are going to apply a sealing/priming coat of epoxy before glassing then doing this before filling may help avoid the filler spreading along the grain and causing a larger area of different colour.

Good luck with it.

Hi fellers, thanks for the replies, I heated up a hobby iron to max and ironed the holes through a wet rag. It worked quite well, I think I will leave it at that and start glassing. Don't use a green ckucks though it leaves green marks! The holes were from brads that I used to hold the planks on. This is a Redfish Silver Kayak. I have some picks here hope they come up ok. Richard G

Good decision!

Since you used small brads, then I am not surprised that the holes have become much less noticeable. By the time you have finished, they will be even harder to see. Some of the wood dust from sanding stays in the holes and when mixed with the epoxy, it looks a lot like the tiny, slightly darker spots that are a natural feature of some timber. If the holes have closed up fairly well, you will have something that is much less visible than any other method you could have used.

The other thing to remember is that while you are working on the kayak, you are staring at those holes from less than half a metre away. Once the kayak is complete, you and admiring friends will be looking at it from a couple of metres away. I bet none of them ever notice what remains of the holes.

Hello Richard,
I would like to know the weight of your "Paulownia" kayak & was it a difficult wood to work, please.

Arthur Smith (WA)

Arthur, Paulownia is typically about 20% lighter than WRC. As a very rough guide, about half the weight of a strip built kayak is in the strips that make up the hull and deck. The rest is in the glass, epoxy, cockpit, seat etc.

So a Paulownia kayak will weigh very roughly 10% less than the same kayak made from WRC.

Other factors such as the strip thickness and the weight of glass used have a huge influence on the weight of the finished kayak, so what one builder achieves by using Paulownia is only a very rough guide to what you can expect if you use the same timber.

For example, my heaviest strip kayak is a 5 metre sea kayak with bulkheads and hatches, but no pump, rudder or compass. It is built from 5mm Paulownia with one layer of 125gsm glass inside and out. It weighs a bit over 13kg. A 4.5 metre version of the same kayak weighs a bit over 11kg.

I have another Paulownia kayak that is 5.2 metres long and weighs just a touch over 8kg. However, it is a racing kayak made with 3.5mm strips and 85gsm glass inside and out.

I have built two strip kayaks using WRC and nine using mostly Paulownia. I have not found any significant difference between WRC and Paulownia in bending, planing or sanding.

Given how many variables there are, about the only definite thing to say about the weight of a Paulownia kayak is that it will be roughly 10% lighter than the same kayak in WRC. So a lightweight, recreational sea kayak could be less than 15kg in Paulownia or 16.5kg in WRC and a fully fitted out rugged expedition expedition kayak might be 20 kg in Paulownia or about 21.5kg in WRC. Most of the extra weight of the expedition kayak will be in heavier glass, requiring more epoxy and more fittngs.