Wood Filler

[Senza Timone]

I finished my first planking. Is not perfect.  Some courses show a shallow step like if using planks of different thickness.

Since the planking is only 2 mm thick I do not want to do some heavy sanding, plus the ship will see water and needs to be water tight.

What is a good sealer to use in this application?

Must dry hard and sandable not mushy like the wood putty used to hide blemish in furniture's

Must have a reasonable work life, I thought of Bondo but is nasty stuff.

Back in the model airplanes days (60 years ago) I used a paste of Talcum powder and Nitrocellulose glue, there should something better today

 

 

[Jaager]

If you scabbed a thin piece of wood to flush out the steps, it could be sanded down to the 2mm level without compromising the shell.  Pine is easy to sand and is not nearly as friable as Basswood.  Yellow Poplar would be good for this also.   If it to be exposed to water TiteBond III to bond the scabs.

[Roger Pellett]

I recommend Durhams Rock Hard Water Putty.  This is a powder that you mix with water.  Mixing is by eye depending on the consistency that you want.  It is odorless, foolproof, and easily sanded.  A large can is not expensive.

 

I have no relationship to the company.

 

Roger

[Bob Cleek]

There are lots of alternatives. Here's a couple that come to mind:

 

1) Seal the hull well with a liberal coating of white (clear) shellac, which is one of the best moisture barriers known to man. Then use Interlux surfacing putty (a chandlery item: https://www.interlux.com/en/us/boat-paint/filler-and-epoxy/surfacing-putty ), which can be thinned to any consistency with acetone, and use it to fill and build up the uneven surface. It will crack when it shrinks as it dries if you put it on too thick, but another application will fill the cracks, so not to worry.  It's better, however, to apply it in layers if the divots are deep. If they are more than 1/8" deep, I'd put it on in layers. When the worst of it is filled, then apply a thinned coat of it (like heavy cream consistency) and let it dry. (It dries very quickly, since the acetone is extremely volatile. Use in a well ventilated place, or better yet, outdoors.) Then sand your hull fair. Surfacing putty will sand like butter. Finish sand to 300 grit. Then apply a coat of thinned shellac over the surfacing putty. This will provide a good base for your finish paint coats. Interlux surfacing putty is made for marine applications. It will not act like a sponge, unlike many similar products like drywall "mud." Apply a base coat and finish coats on top of all that. If you take time to do the prep properly, and apply your finish coats properly, you should obtain a perfect finish.

 

2) If you don't mind working with serious VOCs, another approach is to use WEST System G/flex 650 epoxy resin and hardener (https://www.westsystem.com/specialty-epoxies/gflex-650-toughened-epoxy/)  mixed with WEST's 410 Microlight filler (https://www.westsystem.com/filler-selection-guide/) (or the equivalent) in varying consistencies as circumstances dictate, as with the surfacing putty above. (i.e. fill the big divots with thicker material, then give it an all-over thin coating of the stuff. Microlight filler (similar to "micro-balloons" ) will produce a cured epoxy that also sands extremely easily and can be finished to a very smooth surface. It's designed for use on full-size boats and is waterproof. You can also use WEST System 105 resin and hardener, but G/flex resin is specifically designed to be more waterproof and more flexible when cured than the regular 105 resin. If your planks shrink over time, the G/flex will be much less likely to crack along the plank seams that cured regular 105 resin. After the surface has been faired and sanded down to 300 grit (or even finer, if you feel it needs it,) you can apply base and finish paint coats in the usual fashion.

 

If it were my sailing model, I'd opt for the epoxy because the model will be in the water. The epoxy material are more expensive but you won't need much and epoxy resin, hardener, and fillers have decades-long shelf lives, so you can use it on later models. BTW, you can use the basic resin and hardener with any number of WEST fillers to create various properties and you can use this epoxy for a myriad of repairs requiring maximum strength adhesives. It's useful for a lot of modeling jobs. 

 

Downloadable WEST System manuals: https://www.westsystem.com/instruction-manuals/ and https://www.westsystem.com/the-gougeon-brothers-on-boat-construction/

 

The second URL above, The Gougeon Brothers on Boat Construction is "the Bible" of epoxy use in boatbuilding and all other uses, for that matter. It's treatment of surface glazing at page 158 should be helpful to you when finishing your hull. Those modelers who are considering "going over to the dark side" and scratch-building a model will also find Chapter 16 on lofting starting at page 165 of the book (179 of the free PDF) the best basic general treatment of the subject available for free anywhere.

Edited June 25, 2021 by Bob Cleek

[Senza Timone]

Thank you guys, real good info.

Mauro