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[Barry-C]

Hi
I am restoring and old Bowman pond yacht that I found in an antique shop. The nearest thing to a positive identification is that it may be a 24" Bowman Aquaplane circa 1954. I have stripped the hull and keel back to bare wood/metal (see photo). It is my intention to paint the keel black (as per original model) and the rest of the hull racing green or white or a combination of both.
My question is this:
Do I need to seal the wooden hull before priming/painting it. I have read that it is common practice for planked hulls but I'm not so sure whether it is appropriate for a solid obeche hull. If there is a need to do so can anyone recommend what to use?

[dodgy geezer]

If it is stripped to bare, you will need to prepare the surface before painting.  For this sort of job I use several layers of thinned down sanding sealer soaked well into the wood, but others will all have their favourite techniques...;

[Footski]

I agree. I would use a couple of coats of sanding sealer, well sanded down.

[Barry-C]

Thank you both for your suggestion. I had read about sanding sealer elsewhere (as well as shellac and epoxy). I think I'll go with sanding sealer.
I also read somewhere that you need to be careful that the sanding sealer is compatible with the primer you are gong to put on top of it.
I had been looking at using Tamiya primer and paint. Do you know of a sand sealer/primer combo that work well together?

[JimG]

Tamiya paints are Acrylic basically using an alcohol/water solvent, this is compatable with cellulose, enamel or acrylic paints.Sanding sealer is generally cellulose based so will not be affected by overpainting with acrylic. You will have to allow the solvent in the sanding sealer to fully evaporate before overpainting, so leave it for several days after applying it.My preference would be finishing epoxy initially thinned down to help it penetrate the wood. Adding a second coat will allow it to be sanded to a smooth finish that is harder and more resistant to scratching in use. Sailing the yacht will probably lead to it rubbing along the pond wall, epoxy will resist this much better than sanding sealer.
Jim

[Barry-C]

Hi JimG. I have largely gone with Tamiya because it was suggested to me when I phoned a certain Cornwall based Model Boat shop - but I'd be open to other ideas. I had also read that epoxy might be a more resilient base. Can you recommend an epoxy suitable for the purpose? Is there a brand of paint you would use with that in preference to Tamiya?

[JimG]

I normally use Aeropoxy from Deluxe Materials, normally sold for glass skinning plane wings and fuselages but works as a sealer as well. If the wood has a rather course grain and would normally need several coats to fill it I generally add a small amount of microballoons, very small glass or phenolic spheres that act as a filler but are easily sanded. Both easily available from a good model supplier. Once the epoxy has hardened and been sanded you can use any paint on it, I tend to use Halfords car primer but the Tamiya primer would work well, I have used it on occasions but generally on plastics. One drawback with Halfords white primer is that it doesn't have good covering properties and generally needs several coats.
Jim

[Barry-C]

Hi Jim! Thanks for your advice. I think I'd like to use epoxy but I worry if it's a bit too 'technical' for a newbie like me? Since reading your post I've watched a few videos of people using epoxy with microballoons but in most cases they are mixing it to quite a thick paste used in some cases for strengthening. As you know, I just need something that can be painted on. Could you give me an idea of the ratio of resin to hardener to microballoons I would need?

[JimG]

Hi Barry, the Aeropoxy I normally use is mixed in the ratio of 3 parts resin to 2 parts hardener  by volume. I generally use small graduated medicine cups to do the measuring. I find the mixing does not have to be exact, it will still harden OK just might take a bit longer. If I want to thin this down I generally use some alcohol, isopropyl alcohol will do this, just make sure it doesn't have added water. I can't give any amounts for the microballoons I add as it is just done by eye. You only need enough to slightly thicken the epoxy but it should still be brushable. Adding enough to make a paste is good as a filler or making fillets along joins but not needed if you don't have any holes. You might want to check out just what the microballoons are made off as the colour will differ. The more expensive are glass beads which are white while the others are phenolic which are brown. Which would be best will depend on the colours you are painting.
Jim

[Barry-C]

Hi Jim! I have found that Deluxe Materials also sell microballoons and I am led to believe that they are white in colour. I still haven't finalised the colour scheme yet. My current thinking is that the steel keel will be black while the rest of the hull might be a racing green with possibly a band of white at the top. I had assumed that if I was using a primer the colour of the microballoons wouldn't show through. Is that not the case?

[JimG]

In general the colour is not much of a problem, if you are using a white primer they can sometimes have a poor coverage needing several coats. (Halfords white spray primer is an example) If so then the lighter coloured it is at the start the better.
Jim

[John W E]

hi there,


Although I do agree with a lot that has been said - personally - when covering a hull using only Epoxy or fibre glass - I tend not to thin the product.  The only time I have ever thinnned Z-Poxy finishing resin was on a balsa wood model where I required the resin to soak deep into the materials to create a hard skin; like my wife's heed - then I coated over the top of it just with standard resins and she has never forgiven me cause she cannot get the resin oot of her hair - only kidding of course  .


Couple of photographs where I have used bog-standard Z-Poxy - no thinning.   I put this on with a brush and then smoothed it out with wet n dry, to give the required surface finish for painting  and  I do tend to use Humbrol enamel paints for painting my models.


John

[Barry-C]

Hi John! Thanks for your input. Do you use microballoons with Z-Poxy?

[SteamboatPhil]

Odd fact Baking Soda also works if you don't have micro balloons....no really.....

[John W E]

hi Barry


No, I dont use microballoons or any other form of thickener which is added to the resins, epoxy of Z-epoxy.


The only time when I have ever added anything to the resins is when bridging a gap/re-enforcing a corner joint in the hull where you dont want a sharp corner radius.   You build it out with a thickened resin to achieve the desired radius.


Just as a sidenote though, the 'old' talcum powder does make a good additive and you can mix enough to make a paste - similar to car body filler.


John