Newbie needs help on Smooth finish

[Old Moo 55]

G'day,
I am new to woodworking and am building a doll house using 12mm marine ply which has a very course grain. I want to paint it using acrylic paint and want a really smooth finish without the grain lines (If possible). Is there a spray putty similar to the one available for metal? Or, if not, can you paint acrylic over the polyurethane grain fillers? Any advise would be greatly appreciated.

Thanks. Have a great day.

Old Moo.

[tea lady]

You can sand the ply. Only need 120# or so. If there are cracks you could fill with something like Timber mate wood filler, but the surface should sand OK.

[Old Moo 55]

Thanks Tea lady. That didn't occur to me. I have tried sanding...and sanding...and sanding some more. Only to find as I smooth some of the grain I expose more course grain beneath.
It is a large doll house. 1000mm X 750mm X 800mm high. I have used wood filler on the smaller pieces of furniture I have made with great results. I need an easy to use wood filler for large areas. I thought I might give it a coat of paint to seal it then use the spray putty. I'm just not sure of the adhesive properties of the putty. Perhaps I'll just try it on a piece of scrap. Just thought there was someone out there that may have known to save me the expense.
I have looked up that 'Timber Mate wood filler' and it appears to be what I'm after. Thanks again. Have a great day.

[malb]

Won't help with the current situation, but MDF will give a great paint finish over an undercoat if you go down this road again. Edges may be fibrous, but a good sand cleans them up quickly, or you can give them a skimcoat of plasterboard top coat and then sand them for a mirror smooth base. Lot cheaper than marine ply also if you are buying material.

[antiphile]

As Tea Lady suggested, I would also suggest using no finer than 120 grit sandpaper. Then use an acylic primer (if you are using acrylic paint) and you can often get it tinted to the same colour as your intended final acrylic colour at no additional cost.

On marine ply I'd probably do 2 primer coats and one final coat of acrylic paint, but the choice is yours of course. It all can be sprayed, rolled or brushed.

Irrespective, your daughter will love you -- so don't sweat it too much.

[Old Moo 55]

Thanks guys. Actually the dollhouse is for my granddaughters 5th birthday. Apparently this is a very special birthday in NZ and my daughter-in-law asked me to make something that could be passed down through the family. As usual I have gone overboard. This doll house will have all of the things that were wrong with my doll house amended. It will have working sash windows, a staircase where the doll can actually fit into the above opening, the doors at the back of a room will actually enter into another room, I'm planning on built in mirror robes in 2 of the bedrooms and a glass sliding back door that will open onto a slide out back yard. My hubby is making the table (lol) with a turntable on top. I have no doubt I will call upon your knowledge again before it is done. Thanks once again all you. Much appreciated.
Cheers
Old Moo

[Humphrey9999]

It sounds like you need some 'sanding sealer'. Most hardwares etc carry it. I got some at Mitre 10 in Junction St. (Wattyl Sanding Sealer.)
(Another Nowra-ite.)

[soundman]

If its ply and you are talking long term durability I would be steering away from the " normal" water bassed acrillics.

In general acrillic undecoats do not penetrate into the grain at all, they simply sit on the top and plug up the holes.
The acrillic top coats will generally never dry hard, will mark from pressure and things will stick to them.
AND the films tend to be thick and gluggy.

The only exception may be Resene lustacril and enamacril, which are from the ground up enamel substitute formulars.

My inclination is to go with an solvent preferably thinners bassed primer undercoat applied with a brush then sanded with a random orbit sander to 120 or may be 180.

Its a dolls house, people will get very close to it, a bit of texture that would be insignificant on a full sized house will look like a tiny 1/20 scale person attacked the wall with a pick or has glued 20mm drainage gravel to the wall.

My preference would be an automotive primer, but any fine primer will work.....but ya need something with a fair share of resin rather then big lumps of filler.

I've done quite a bit if finishing of ply, you need to be aware that the surface is full of very fine cracks due to the veneers being rotary sliced, if you want a realy nice flat finish you need something to fill and bond these cracks.

I've tried timbermate and it simply has no bonding ability and sanding after pulls most of it right back out of the grain.

I have had best sucess with estipol sanding sealer and superetch metal primer/undercoat ( which works fine on wood and is my go to opaque undercoat).

Shelac either as it is or bulked with a little talc would work as would many other things...but ya need a strong fine resin that will get into those cracks.

Yes sand the raw ply to 120 with a random orbit sander, just to knock the tops off and remove any fuzz.

go a fairly thin first coat, double coating your edges, edges first, do the flat bits, edges last....this will "get in" and crisp up the grain so it sands well.
sand 120 again and lay up another coat, keep the primer reasonably thin and sand again.


After 2 coats look at the surface if it is not completly flat and choked out, go another coat and another if needed.

With thinners bassed product you should get 3 coats both sides in a day if the weather is warm..shelac wont be far behind.

I always use a brush for early primer coats on wood because it allows you to grind the finish into the grain.

You should be able to produce a perfectly flat, and hard base on which to work, you would also be surprised how much extra strength this will give to realy thin ply.

If ya realy want a good finish I would spray the last coat of primer and the top coats of colour, as usual all the details can be done with a little brush and little pots of paint.

If you like polyU sanding sealer, don't be affraid to consider pollyU paving paint as ya top coat.....just ignore the word paving on the can....its an opaque polyU and behaves pretty much like pollyU varnish...colour choice is not fabulous though....certainly hard wearing and buffs out very with some 1200 and some wax later.

cheers

[Lplates]

Hi Old Moo,

I would be inclined to agree with soundman regarding automotive primer/filler. I've used this before and it produces a very smooth finish, especially if you sand down with fine grit after every second coat or so (probably not necessary though). It is available in spray cans which is what i used. It's the best way to apply if you want a smooth finish. Use several thin coats instead of a few heavy ones and you'll get the best results.

Alternatively you could use shellac. I've never tried painting over it but you can apparently put anything on top of it once it's dry. The great thing about shellac is that it dries very quickly because it's mixed in alcohol. The way i used it was to apply two thin coats over about 30min (ie 15min for each to dry) to a pre-sanded surface (down to 240g). Then i sanded very lightly with 320g to remove the raised grain, then applied another coat, 320g again -> another coat -> 320g-> another coat 400g -> another coat-> 600g. Don't be put off by the sanding in between, you only need a couple of fine strokes to remove the rough feel of raised grain. The wood comes out super smooth. If you have some shellac i would suggest trying it out on a test piece to see how it turns out. If not you can get shellac flakes at most of the big hardware places, you just need to mix it up with metho. Just don't mix up the whole lot unless you plan to use it as it goes off after a while. As for the mix rate, i just mix it by eye but most manufacturers will have their own specifications (usually 250g per litre of metho or so...)

Good luck.

[Old Moo 55]

Thanks Guys,
You have answered all of my questions. The finish you suggest is just what I want. As I work full time, am a mother/grand mother to boot it may take some time. But I'll get there. Thanks again. Have a great day.
Cheers.