Sanding sealer

[UglyDan]

Hi there,

Have been working on a table top and thought id try some WOP. After reading a few posts on using sanding sealer's prior to finishing, I thought id give it a go.

Initially looked ok but had a few streaks. So i went to do a bit of light sanding but to my dismay, the dust began clumping together, on the paper and wood. Eventually i got a relatively smooth finish but it was a sanding nightmare

Was wondering what i was doing wrong? When i use shellac or danish oil, the sanding is a dream but this was horrible!

[Mr Brush]

Depends what type of sanding sealer you used......

They seem to fall into two categories; thin shellac-like liquids (a al U-Beaut) or thich gluggy concoctions with lots of filler in them (e.g. Feast Watson).

After a horrible experience with the latter, I only use thinned white shellac as a sanding sealer these days. Shouldn't need more than a light denib before applying finish over the top.

The FW gluggy stuff........well, that could take a LOT of sanding back.

[UglyDan]

Thanks Mr brush - I used the 'WATTYL' sanding sealer.....like what you experienced its very gluggy when sanding, not sure if i was doing something wrong or if it was the product itself.

Like yourself I have had really good outcomes with the shellac as a sealer, sands fantastic!

Heard lots good things about the 'U-Beaut' sanding sealer, maybe I should give that brand a go before writing it off, im sure bunners should have some instock

[KevM]

Heard lots good things about the 'U-Beaut' sanding sealer, maybe I should give that brand a go before writing it off, im sure bunners should have some instock

Click here for Queensland stockists.

[joez]

How long between sealing and sanding?

Also what were you sanding with? Hand/RO Sander, any type of dust collection? What grit sand paper?

Personally I find if its clogging when hand sanding, the sealer isnt dry enough.

If its clogging when machine sanding the sealer isnt dry enough or there isnt adequate dust collection.


joez

[Mr Brush]

I suspect the Wattyl stuff is the same as Feast Watson.....it has a LOT of solids in it. It was like there is a lump of putty in the bottom of the can, which takes a lot of stirring to get it to dissolve into the liquid. I'd never use it again.

The U-Beaut stuff is the way to go. I use only U-Beaut sanding sealer or U-Beaut white shellac (heavily diluted) for sealing. Whichever I happen to have handy. Maybe our fearless leader could tell us the difference between these, as both seem to work equally well ?

This should need nothing more than a light denib by hand sanding.

I can only presume that the Wattyl/Feast Watson stuff is supposed to work as a grain filler as well as sanding sealer (whether you want the grain filled or not.....)

[rsser]

Nitrocellulose sanding sealer needs to be diluted with paint thinners. Start with 50:50.

[UglyDan]

Thanks for the responces

KevM - Nice one, I get my timber from one of the suppliers on the list so ill pick some up and give it a go

Joez - I let it dry overnight, gave it about 10 hours before i started sanding.I started with a RO with 400grit, straight away i noticed the clumping and began by hand, same thing... Might be right, temp overnight might have been to low and it may have needed more time.

Still got quite a bit of it left so might try rsser's idea on some scrap and thin it down, give it a bit more time to dry and see if it comes good......will still give the U-Beaut a crack

[rsser]

It's not a grain filler. It stabilises the wood fibres as a prep for sanding.

[ubeaut]

The U-Beaut stuff is the way to go. I use only U-Beaut sanding sealer or U-Beaut white shellac (heavily diluted) for sealing. Whichever I happen to have handy. Maybe our fearless leader could tell us the difference between these, as both seem to work equally well ?

Sanding Sealer is basically Dewaxed Bleached Shellac (our White Shellac) cut with around 10 parts of 100%IMS (Ethamol) so, basically the same thing. If you're keen enough you can actually french polish with the Sanding Sealer.

You can use the White Shellac as a grain filling sealer if you add a small portion pure talc eg: 1 part talc to 200 parts of 50/50 mix shellac. The shellac and the talc help fill the grain whilst the talc makes the sanding much easier. Which in theory is what the solids in the thick sanding sealer is also supposed to do.

I was always under the impression that the Nitro and poly type Sanding sealer were to be used to fill the grain, because they were easier to sand and a hell of a lot cheaper than the finish itself. Haven't purchased any for many, many years but I'd hazard a guess that the sealer isn't all that much cheaper now than the finish itself.

Below is an extract from EROLUX Product Information on their Nitro Sanding Sealer

A high quality nitro sealer with a very good body. Resistant to over spraying. Nitro sanding Sealer is designed for excellent wetting of the structure of wood and provides a perfect colorless base prior to top coating.

CHARACTERISTIC

• Sanding Sealer represents the ultimate in transparent wood fillers. It is a modern do-it-yourself product with a dual purpose – it beautifies by filling in all the open grain and slight imperfection in timber and gives surfaces a silky smooth base for top coating with clear varnish. Sanding Sealer is the modern practical way of giving all interior woodwork such as panelling, built-in cupboards and furniture the best finish possible.
• Apply a thin sufficient only to fill the grain. Thick coats will necessitate a considerable amount of unnecessary sanding since for the best results, it is important to remove all the dry sealer from the wood. Residual will show patchy areas under clear top coats.
• Do not stain after the application of Sanding Sealer. Allow the sealer to dry for ½ - 1 hour and carefully sand with 320 water papers. For the best results the Sealer should be sanded away, completely i.e. until only wood is exposed.

Hope this is of some help and interest.

Neil

[rsser]

Great advice from the Guru as always.

I should've been clear that I use diluted n/c sanding sealer on woodturnings as a prep for sanding and then application of Ubeaut wax. Only on light coloured woods; darker, oil-based finish is my pref.

The stuff I've sourced is from the Woodsmith. Last batch IIRC from Paintmobile. The dilution is important since you want it to soak into the wood.

Method: paint the sealer on with a brush; slowly spin the piece in the lathe taking the excess off with a clean lint-free rag. Then cut with 0000 steel wool. Neil would advise against that but it works if there are no voids and the grain is not open pored or coarse.

Just as a btw, the combo is great for green turnings done in one session. The wax shine may drop off in time but can be reapplied by hand.

The Erolux is clearly meant to be both sealer and filler.

That aside, Ubeaut white shellac is great stuff; easy to work with, water and heat resistant as a final finish and comes with decent instructions on the bottle and online.

I've dabbled with adding talc and didn't like the clouding effect on darker woods but I don't have Neil's expertise. I prob added too much.

[Mr Brush]

Thanks Neil - that's one of life's little mysteries sorted.

I generally have some Ubeaut White Shellac handy, so just decant a portion to dilute as sanding sealer. I may even experiment with talc as a grain filler additive - hadn't heard of that one before.

The FW and Wattyl sanding sealers have a LOT of filler in them. You'd have to dilute them heaps to make them work in the way I thought sanding sealers were supposed to. After trying to use the FW version once I used about a third of the can, and threw the rest out in disgust. After laboriously sanding back, and many clogged papers later, the stuff had totally obliterated any grain in the timber.

I'll stick to the Ubeaut stuff thanks.

[woodmark]

I've applied the shellac as a sanding sealer to some raw timber (New Guinea Rosewood cabinet doors), lightly sanded back, and it's delightfully smooth! )

But, before I coat with oil-based poly,what should I use to clean off the light amount of dust from the sanding? Turps on a rag?

[AlexS]

I clean up the dust using white spirits, but turps is probably just as good. Don't use metho, as it can soften the shellac.

[UglyDan]

Thats come great info! Cheers

Picked up some ubeaut sanding sealer today. Cant wait to see how it goes on a few test peices.

Pretty convinced now that the problem was not thinning the sanding sealer down first. So will try it again and compare the difference.

Cheers