Filling in Wood Grains Question

I am building the Billings Boats US Coast Guard Nr. 586 rescue boat, the big model.. It was already started by someone else, just the
below deck hull bottom parts, when I bought it at a bargain price. Over the years I tried to build it but the parts didn't seem to come together and I couldn't quite figure out why. I guess the original owner had the same problem. Recently I had another go at it and realize that the kit had a major parts problem. The main deck which should be flush with the gunwales isn't in the kit's die cut parts. Its as much as an inch lower into the hull. Of course nothing else in the superstructure will assemble to look like the box illustration. Anyway to cut a long story short I plotted the lines and made a correct deck out of door skin plywood.
I need to make the plywood as smooth as plastic so to say. What kind of filler should I use? I will sand it and seal with Varathane once smoothed.
I need the same solution for redoing the trim on my house doors and closets too. The sealer recommended by the paint shop still leaves the wood grain showing through the paint. Someone suggested that the wood filler used for renovations is just ordinary drywall mud. Somehow I am not convinced that drywall mud will stand up to the knocks and bumps from model RC operation. Comments?
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PaPa Peng wrote the following:

How about Bondo auto body filler?
--

Bill
In Hamptonburgh, NY
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Will try. Offhand I think the wood grain lines will be too shallow and thin for the Bondo to adhere to.
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I remember way back when, using super glue to seal wood. Brush it on, let it dry, sand and paint. YMMV.
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On Mon, 30 May 2011 06:09:06 -0700 (PDT), PaPa Peng

Wood working techniques might be in order. Wet the surface to intentionally raise the grain, let dry completely and sand back to smooth. Also prepping the surface with wood specific finishes like hard floor acrylics..... Grain and hardness of the wood will be an issue. Talk to someone who refinishes furniture. They know about smooth.
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On May 30, 12:38pm, snipped-for-privacy@ripnet.com wrote:

That technique is correct, but "wetting" it can be done with Varathane, sanded in between coats. Eventually the grain will be sanded smooth with finer sandpaper used with each coat. I've always used oil based, but the new water based products should work.
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I would think a wood sanding sealer. hat's what I use on balsa, etc.

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