Sanding and Varnish for Wood

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DafyddElvy
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Sanding and Varnish for Wood

Post by DafyddElvy » Sat Jul 17, 2021 5:01 pm

I am scratch building some 7/8ths scale coach bodies in basswood, what grade of sand paper would others suggest I use before varnishing and what varnish would others suggest for coaches that have a wood varnish finish.

Wood and I are most definitely not best friends and its normally a material I would avoid, but the models need to have a real wood finish so I am taking the plunge with this material.

Any advice for building wood coach bodies would be gratefully received, thanks.

David

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Peter Butler
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Re: Sanding and Varnish for Wood

Post by Peter Butler » Sat Jul 17, 2021 10:19 pm

Hi David, I think my initial response would be.... don't do it! However, if you feel the need, despite your reluctance to use wood anyway, I suggest a very fine grained, hardwood, 1 or 2mm plywood, the sort usually available in good model or craft shops. If you are intending to make the natural wood the final varnished finish then this will be fine. It will be essential to mark-out and cut all surfaces with special attention to the direction of the grain.
By the time you have sanded (fine wet and dry paper is probably a good material to use, but not wet!) and then painted or varnished the ply, you will have pretty much obliterated the grain effect anyway.
For final varnish I use Halford's Clear Lacquer (for a high gloss finish) or Satin Lacquer for a less shiny surface which lessens any imperfections shown up with gloss.
It is most important that you get no adhesive on any surface which might need to be stained afterwards as this will repel any wood-stain.
If you are planning to add overlays (panel frames) it is always best to apply these after the main bodywork has been completely finished for the neatest effect.
IMG_7326.JPG
I hope this is helpful...... it works for me.
The best things in life are free.... so why am I doing this?

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Re: Sanding and Varnish for Wood

Post by Tingewickmax » Sun Jul 18, 2021 1:15 am

I usually start with 240 grit and finish with 400 to get the wood's initial surface down to something that will be smooth to the touch suitable to work from. Various types of abrasive sheet materials are available - they all work well. Assuming you are working on flat or single curvature surfaces mount the abrasive sheet on a sanding block or create your own sanding "tools" to suit the size and shapes of the surfaces to be sanded. It you want to colour your wood, rather than rely on the initial finish of the material used, my preference is to use spirit based wood dyes. They can be used straight or mixed to acheive a desired tone - keep in mind the base tone of your wood will affect this. You could varnish with a sanding sealer alone - 2 coats rubber down between, 400 grit followed by 800. If you feel inclined a bit of fine grade wire wool can be used too. All that will bring out the wood grain's natural appearance.

Then, if you wish, finish off with a coat or two of an interior or exterior (yacht) grade varnish with the finish of your choise. You could also "tweak" the final colour by using a wood stain/varnish instead to compliment the dye used initially. Don't be afraid to brush on the various finishes, you will be surprised at what can be acheived with a decent broad "artist's" brush. Any dying and sealing must be done before any gluing or assembly but any final varnishing can be done after. Experiment a little before you build to find what works for you. Usual caveats about ensuring everything is compatible.

If you can get a chance take a look at an OcCre (tram) kit some time. Their construction methods - a mix of 3 mm plywood framework, clad with 0.5 mm birch ply and various strip woods for both structure and laminating is quite enlightening. Look at the materials a model boat shop stocks, if you haven't already, again enlightening for project like this. I use Cornwall Model Boats Ltd https://www.cornwallmodelboats.co.uk/index.html Max

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DafyddElvy
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Re: Sanding and Varnish for Wood

Post by DafyddElvy » Sun Jul 18, 2021 12:07 pm

Wish I'd asked questions first before using the materials I have in stock, basswood doesn't seem to be the wood of choice for coach build, unfortunately I have already cut the valances for 3 coaches, ho hum.

With wood I have learnt cheap means just that, I've used cornwall boats for items before and found them to five good service.

Thanks for the advice, I'm off to see what cornwal boats has to offer.

David

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Re: Sanding and Varnish for Wood

Post by Tingewickmax » Sun Jul 18, 2021 1:32 pm

Nothing wrong with basswood. I have just been reading an article in the Narrow Gauge and Short Line Gazette where it is being used to build a box car, although in a smaller scale to 7/8"ths. Its fine grain may well make it ideal to represent "scale" wood grain in the built model you desire.

Fun fact about hardwoods - Balsa is a hardwood. Back in the 1960's McLaren built some racing car chassis (the very successful M6 Can-Am car was one), designed by Robin Herd, out of a material known as Mallite. it was a composite material made from a balsa core sandwiched between aluminium sheets. Now there's an idea for a model building material :) Max

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Re: Sanding and Varnish for Wood

Post by Phil.P » Sun Jul 18, 2021 8:04 pm

Basswood is quite soft, so go easy with the sanding, until you get a 'feel' for the material..

Nobody hasmentioned:
Always... Sand in the direction of the grain.

Phil.P

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