Thread: Finishing radiata with varnish stain

Gday Jill, if it wm I would first wet the pine with water to raise any grain then sand 320 grit then 400 grit.Radiata will often be blotchie, good luck

Do not sand radiata any higher than 240 when staining, it doesn't "stick" if you do, also allows varinsh a "key in" to adhere to the wood.

According to Cabots, sand to 180-280, and apply, sand in between coats with 320,(I'd put at least 2 coats on before sanding to prevent sanding through them), apply coats until desired colour is achieved then cover with something clear.

thanks for this information, guys. Would you consider diluting the first coat with turps?

Originally Posted by JillB

thanks for this information, guys. Would you consider diluting the first coat with turps?

Not for this stuff, but test pieces are your best bet, do a few, also check that you don't use to many coats before you can sand etc.

I think some may have missed the point... You are using a single product (Cabots Stain and Varnish). From my limited experience, the biggest problem is getting a nice even thicknessed coat as the thickness will affect the colour you get. The colour is determined more by the thickness of the product than its absorption into the wood. I think I would prefer to spray it on.

These are the hints from Cabots website

Note point 2 in particular which could help to reduce blotching on pine.

Handy Hints



When the desired colour or transparency is achieved with one or two coats of varnish, finish the three-coat system with clear top coats. Eg: One coat varnish plus two coats clear = three-coat system




For fiddly, porous and hard to reach areas, seal first with Crystal Clear Satin (under Interior Varnish Stain) or Cabothane (under Stain & Varnish) to eliminate product ‘grabbing’ and building up.




Always stir contents thoroughly with a wide, flat bladed stirrer, such as a wooden ruler, before and during use. Do not shake cans as this action will aerate the contents and cause air bubbles in the coating. Stir with a scooping action.


The comments about wetting it down with a damp cloth and a final sand is very good as is Cruzi's advice to put a couple of coats on before sanding and being very careful not to cut through it as changing its thickness will alter the colour.

Bottom line, pay particular attention to the eveness of your coats.

Good luck with it all and let us all know how you get on.

Chipman

(you could experiment with thinining it with 25% turps and using a lint free cloth to rub it on. I have never tried this with the coloured polyurethane but regularly do it with the clear finish)

The wetting and sanding is pointless for varnish finishing, great for shellac and wax finishing though.

Wetting and sanding

I agree that wetting and sanding is more important for shellac and mandatory for water based stains and finishes but I still like to use it with varnish finishes when working with pine. This is what I have noticed...

If you final sand to say 320, damp it off and sand again with 320, I get less "fur" or nibbing. It also tends to show up any places that might have a smear of glue that affects staining and gives you a chance to remove it.

True, a clear coat of sanding sealer or light coat of lacquer followed by a light sand to denib the finish will work very well too. As stated above, I notice less nibbing when wetted down and sanded. Even with solvent based finishes you get a bit of grain swelling in soft timbers like pine, especially if any hard or heavy machine sanding has been done on it. (Observations of student work at school with radiata pine)

Regards,
Chipman

thanks Chipman and Cruzi, very valuable advice. As a newbie, can you please advise the term "nibbing" in a woodworking context, as you guys understand it, and why radiata stained finish will be blotchy?

kind regards,
Jill

Hi,

First the easy part... Nibbing is a term that refers to the little wood fibres that tend to stand up from the surface after being torn by sanding/working the surface. This is why when finishing your wood with shellac, lacquer or varnish it often feels a little rough after the first coat when it was super smooth before the finish went on.

The little torn fibres can swell up and stand up from the surface. A very light sand or a rub over with very fine steel wool (or equivalent) smoothes them off and the coating prevents more standing up. (It can also go a little rough if it has not been thoroughly dusted off (use a tack cloth if you can which is a lint free cloth like cheese cloth that is a little sticky to touch)

Another reason for sanding between coats is to provide a key for the next coat to adhere well to the previous coat (this applies to varnishes and paints) Lacquer is solvent based adhesion (next coat partially dissolves the previous coat and so sanding between coats is not so essential for adhesion) This is another reason why with "varnish" or polyurethane there is no need to go overboard with the super fine sanding of the wood as the smoothness is obtained by flattening the successive coats of varnish which act as a filler anyway.

Now for blotchy staining of pine..
There can be quite a few reaons.

1. Pine can be waxy or resinous and it is seldom even all over. Where there is more resin, the stain will not be taken up the same. You will notice that around knots the stain will not be taken up well either as the denseness of the grain prevents it being taken up.

2. Sanding. The rougher the surface, the more the wood will pick up the colour of the stain. This is why last night Cruzi was talking about not going beyond 240 grit. Super smooth pine will not pick up so much colour. The waxy nature of pine can also prevent it from sanding evenly too due to clogging etc.
Another issue is with machine sanding (such as belt sanding) if it goes a little deeper in places, it won't get sanded as smooth with the final fine hand sanding in those places.
As pine is soft even the slightest sand across the grain will show up when stained so this is another area to watch. I have found the use of some orbital sanders will leave swirl marks that will be darker too. Good quality sanders will leave little in the way of swirl marks and the last time I used one I think it helped to even out the colur although a little darker than from hand sanding with the grain.

3. Gluing is also an issue. Obviously the presence of glue on the wood will prevent the take up of stain. Usually we use a wet cloth to wipe/wash the excess glue off. I have noticed that where this is done, the wood usually stains a little darker too. It is unlikey to be the glue as this prevents the take up of stain. I think it is more likely to be the rag rubbing across the fibres roughing them up a little and making them take up more colour.

4. Finally their is the application of the stain itself. If it is poured on or applied unevenly then the colour is uneven too. (This is why some use a spray on stain)

I would never call my self an expert as over the years, getting a good finish, especially with pine is something I have struggled with and I have tried lots of things and found out what works best for me. As an example, when I made some furniture recently with deep closely spaced shelves, I made all the parts and just tacked the cupboard together. I then dismantled it, stained all the panels with a water-based gel stain, did the final assemble with glue and then put on the polyurethane. I was pleased with the results.
I have also found that with very special jobs I am doing that burnishing an oil based stain into the wood (using fine sandpaper to sand the stain into the surface and fill the grain) will give a smoother and more even finish but is messy and time consuming.

With what you are doing the colour you will get will come largely from the thickness of the coats rather than absorption into the wood. I have never tried it but I think some put a coat of shellac on first, let it dry, very light sand and then spray on the coloured varnish(with stain incuded) like you are planning to do.

Best thing, get as much advice as you can and work out what works best for you! (Try a re-visit to a post by Harry72 on a previous post by you on thining wattyl stains, he had excellent advice)

I hope this helps a little,

Chipman

Wow!! Many thanks Chipman for this very professional and very helpful advice. I really appreciate the time and effort involved in prioviding all this information.

I am now sorry I am using pine. This is probably the reason others on this forum refer to it as 'crapiata'; but I shall make the most of it.

kind regards,
Jill

Jill,

Don't be sorry!

With just a little care, pine can be made to look very nice.

Here is a picture of a natural pine clock made as an experiment before making the same one out of fiddleback red gum (this is one of my wife's favorite clocks!) no stain and sprayed with polyurethane (pressure pack)

Also a blanket box stained with cabots oil based interior stain and hand rubbed with polyurethane

An entertainment unit with wattyl water based gel stain and brushed polyurethane.

I have made all my furniture out of pine, except for the Grandfather clock, and I am happy with it. When I started, that was all I could afford and I have stuck with it.

You can do it!

Chipman

many thanks for your encouragement, Chipman, very much appreciated. The results you show are very impressive

I am at the stage of dismantling the project, ready to stain the shelving that is too tight to normally get at. Have applied masking tape to the dado slots in the case, and to the ends of the shelves. Just waiting to finalise the woodfiller colour - am currently testing the pine and the mahogany tinted wood filler with the spirit based stain and polyurethance finishes.

kind regards,
Jill