Varnishing - "Sanding Sealer"???

[David_Old_Jersey]

Just spent a couple of happy hours with a hot air gun on various pieces of varnished trim removed from the boat - a mixture of plywood and solid timber - which look like mahogany (at least ish!) to me - a bit of water staining - but yer would need good eyesight to tell.

My usual OP once sanded down to bare wood is:-

a) Apply some Wood Stain and / or Linseed Oil
b) First coat is a thinned coat of Varnish
c) Apply a couple more solid coats and rub down every 2/3 coats
d) finish after 5/6/7 - depending on when I get a coat that looks good!


Usually looks ok and has never dropped off (interior anyway!) - the finish I usually aim for is clean and neat, rather than Vintage Riva mirror like. BTW this time I have a tin of International Goldspar (Polyurethane) to play with.

However I did a bit of Googling on Oxaylic Acid products as a wood bleach to remove water staining (looking ahead to the saloon where some is fairly visible on veneered ply ) and figured I would do a try out on the bits I have now......

.....anyway, I came up on Google with a few folk swearing blind that yer should not apply wood stain direct to the wood, but first use "Sanding Sealer" and then apply the stain as this makes the finish a lot better.
Firstly, I have never heard of "Sanding Sealer" and secondly as you can see from the link to a product Rustins Shellac Sanding Sealer the advice seems to be the other way around

Anyone got any opinions?..........before I try each way


BTW I did a Search on here (with da "Good" Search tool) - some very interesting threads.

[imagine2frolic]

I too have a few waterstains. I sanded down to raw wood, and used the West System with 207 hardener. I put varnish over the top of that, and it looks like glass

[Alan Wheeler]

Yes you stain the wood first. After all, it is called wood stain not varnish stain :-) Of course, you do want to use a good stain as not all stains are good. The reason you stain the wood is it works into the timber and enhances the grain of the timber. If you apply to a coat of something that has sealed the timber, it will sit on top and not look very good. Another method is to use a Varnish type coating with the stain actually in it. But there are several negatives about doing so. Stain in the bare timber is easier to control the darkness and colur of the timber. In fact some solvent based stains you can apply several coats of and they will maintain the colour as the same tint as the original. If you apply after a coat of sealant, the stain can become darker with each coat. The same with a tinted varnish. It becomes darker with each additional coat. With clear coats, you obtain the depth of gloss and the original stained timber remains the same.
Of course there is one negative. Once you have stained bare timber, it is usually for good. You can not simply sand off the stain as many soak deep into the timber. So the colour you choose now is the colour for life.

[Beausoleil]

There's one case where I'd use sanding sealer before applying stain: any exposed end-grain should be sealed with a cut-down sanding sealer.

The ends of the wood grain are actually cellulose-based capillaries for moving water/sap thru the wood when it was still a tree - the open end of tubes (not to be confused with that Internet-thingy composed of tubes as Alaska Sen. Stevens talked about) will soak up a lot more stain than the surface grain, and will appear much darker if not sealed beforehand. Thinned sanding sealer (or thinned varnish) will prevent that and make for a more even-colored finish.

[David_Old_Jersey]

End grain? - maybe that is what is confusing me on the Sanding Sealer.......cheers folks.

Stain - I tend to include this in my Bodgers tool kit as it hides a few blemishes - or at least makes them a bit harder to see Although I do like a bit of varnishwork, it does not dominate - plenty of contrast down below - so woodwork being a bit darker is no problem.

Did me sandpapering earlier today - wood always looks great when wet - shame now that dried out they look pap .......will throw in some more "preparation" tommorow.......

[Weyalan]

I'm only a "bodger", with no claim as to expertise, but personally, I wouldn't put any oil on (linseed) prior to varnishing. I tend to go as follows:
Sand
Clean with acetone or similar
2-pack timber preserver (Everdure, or equivalent), at least 2 coats, preferably 3, and 5 or 6 on the end grain, light sand between coats if necessary, clean and wipe with acetone after sanding
2-pack varnish, as many coats as necessay, with light sand, clean and wipe between each coat

[MidLandOne]

Timber in the interior of sail boats (and powered ones) should be sealed with an epoxy sealer such as Evadure (as Weyalan indicates) or thinned epoxy and with many coats on the end grain of plywood panels. It will also prevent water staining where that timber is to be varnished. A good builder will do it as a matter of course for ALL timber in the boat but will do test pieces first to ensure no undesirable colour cast is introduced where it is to be varnished.

How one gets on if one wants to stain the timber on purpose as well as seal it with epoxy I have no idea (all boats I have been involved with the finishing timbers have been selected for the grain and natural colour wanted) but a trial might show that staining then epoxy sealing works ?

[Wotname]

FWIW, I no longer do a solvent wipe down before applying coating (epoxy / varnish / primer etc) after sanding. The reasoning is the solvent wipe down just spreads the contaminants further over the work; the wipe down cloth is usually full of the stuff you want to remove (unless you use a new cloth after every couple of wipes); the health reasons of using LOTS of solvents (both quantity and type) and finally the cost.

If the wood has potential oil/grease contamination, I will solvent wipe down before sanding, then sand - keeping the fingers OFF the wood -, vacuum the dust away and then coat. If necessary, I might do a light water wipe down, another very light sand after it has dried and another vacuum. The vacuum cleaner has become my constant friend, acetone my enemy!

BTW, a cabinet maker once told me that there are no eyes on the tips of our fingers so we don't need to run our fingers over the work during and after sanding to check how smooth it is, just have a look. This keeps the body fats off the work. I found it hard advice to follow but his work was always better and faster than mine so follow it I did.

Also he never varnished immediately after sanding - he would wait at least several hours (or overnight) to let the dust settle out of the air, wear clean clothes, vacuum everything again, then varnish - Yep tedious but final result was GOOD.

However if others have a better way, I am all ears!

[David M]

I second the West Systems epoxy (part B has UV protection). It comes out looking beautiful and it is much more durable than one part varnish.

[Wotname]

DM, I assume you are talking exterior here, if so what does the UV stable West epoxy look like when cured, is it still clear, darker, slightly cloudly, yellowish???? I use a UV stable(ish) Aussie expoxy that really needs a 2 part poly experior UV stable over it to become fully UV stable but it has a very slight white(ish) colour to it when cured - not really noticable when overcoated with the 2 pack poly varinsh and does last well outside (even with the big ozone hole over us!!!).

[David M]

Originally Posted by Wotname

DM, I assume you are talking exterior here, if so what does the UV stable West epoxy look like when cured, is it still clear, darker, slightly cloudly, yellowish???? I use a UV stable(ish) Aussie expoxy that really needs a 2 part poly experior UV stable over it to become fully UV stable but it has a very slight white(ish) colour to it when cured - not really noticable when overcoated with the 2 pack poly varinsh and does last well outside (even with the big ozone hole over us!!!).

The part B resin when wet has a reddish tint from the UV filter but you don't see the red after it has been applied. Its very clear and it looks quite good after it has cured.

[Alan Wheeler]

The part B resin

What is the No.
I didn't know anyone did a UV stabilized Epoxy.

[David M]

Yes...West Systems has a part B epoxy hardener with a UV filter specifically for varnishing wood.

Product 207

[Wotname]

Yes... and Bote Cote has a similar part B - although they suggest to overcoat with a 2 pack poly varnish for best results. They claim far better life than 2 pack poly varnish by itself. I have used this system on the tiller and it is looking very good after a couple of years. In the past, I just used the 2 pack poly and would be having to redo it by now, so I think their claim is justified.

[stuffinbox]

Greetings,
I like the info on this thread. I am tooling up to begin interior teak refinishing and the greater portion of the surfaces are in good condition needing only light sanding and a topcoat of a satin finish varnish. The problem areas, the comanionway steps, splash areas around the galley sink and some often used lockers need removal of the finish to wood and complete recoating. The PO used furniture polish and all of them have silicon in the polish. Before sanding I think a cotton cloth wipe with reducer, mineral spirits as this is comatible with the varnish, should remove the residue and contribute to the results. I read in previous threads the use of acetone or MEK was suggested but I hope I can get by with something less offensive. Tara has enough square footage of teak in her interior to take months to refinish doing a section at a time.
Thanks