How do I eliminate persistant brush marks in Wattyl water based Estapol ?

I'm using the Wattyl water based Xtra Clear Estapol to finish a table top. The undercoat is Wattyl Sanding Sealer. I'm complying with the data sheet guidelines re temperature, etc and I've never had a problem with painting or varnishing until now.
After sanding off my first attempt because of brush marks in the finish, I purchased new supposedly good quality brushes re applied the estapol and find the same problem with brush marks. I thought I was applying a generous amount to ensure it had time to set and level but still a problem.
Any suggestions as to what I'm doing wrong?

To prevent brush and lap marks I use Penetrol. Works very well.

Check compatibility, of course.

Cheers
Arron

Sorry, just reread your post and realised you are using water based product. Penetrol is no good for that. You could check out its companion product Flowtrol which is intended for water based finishes, but I haven't used it so can't recommend it.

Your experience with water based polyurethanes is exactly the same as mine. I believe they simply dry too quickly to give the finish a chance to 'level out'. They might be smelly and evil but oil based poly's give a much better finish.

I had the same problem with oil base polys and and resorted to a spray gun. Perhaps heat the poly by sitting the can in boiling or very hot water long enough to raise the its temperature.

As mentioned some of these finishers do dry quickly,I use a small foam roller to get a generous coat on quickly

One of the persistent problems with most waterbased finishes is that they don't flow as well as most solvent based. This problem is excarbated in warmer weather.

Most paint manufacturers sell a Hot Weather Thinner, basically a glycol based product, that when added to a waterbased finish keeps the film open for longer and aids in flow.

Dulux have one

Product Detail

and Solver (now owned by Wattyl) make one as well.

Thanks guys. It appears the consensus is the quick drying time may be the problem so I'll buy a product as you mentioned BigShed. I'll also use it when it's cooler - though I thought 20 degrees C would have been cool enough.
I'll post results here.

To look at it another way and what I was alluding to in my post, if the poly is too cold it won't level, being warmer it becomes less viscous and will spread better. It can't hurt to try a test piece using that method.

Chris, whilst what you say is true to a certain extent, it is a double edged sword.

Warming up the waterbased poly will bring the viscosity down, although not as much as with a solvent based poly, but it will also set off the drying quicker thereby hampering the flow more.

The addition of the Hot Weather thinner (usually about 50ml per ltr) will also lower the viscosity, but more importantly it will keep the film open because it is very slow evaporating solvent allowing the finish to flow out for longer.

Perhaps a different approach could be considered. When I apply a finish I generally tap the brush dry and apply a very thin coat and it might need more coats to give the same protection. Generally most of my finishing via a brush is water based.

Quote:

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Originally Posted by harry wall

I'm using the Wattyl water based Xtra Clear Estapol to finish a table top. The undercoat is Wattyl Sanding Sealer. I'm complying with the data sheet guidelines re temperature, etc and I've never had a problem with painting or varnishing until now.
After sanding off my first attempt because of brush marks in the finish, I purchased new supposedly good quality brushes re applied the estapol and find the same problem with brush marks. I thought I was applying a generous amount to ensure it had time to set and level but still a problem.
Any suggestions as to what I'm doing wrong?

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Hi Harry,

Many on here are much more experienced than I am and I suspect that Big Shed and Christos's comments are right on the money.

My main contribution is to reassure you that success is achievable as I have used the same water-based Estapol (low sheen) with absolutely no problems at all. I would not have thought 20 degrees would be hot enough for fast drying to leave brush marks, but it may depend where you are in this large country of ours. If the humidity is very low it will suck the water out of the Estapol and may leave you brush marks. I was using it in Brisbane so reasonably humid - no problems at all.

I applied the Estapol fairly thinly, not generously as you would do for an oil-based gloss paint, so there wasn't much opportunity for brush marks. I also (as christos above) used a fairly dry brush and brushed it out as thin film.

Good luck

David

Update....
I purchased an acrylic paint conditioner (at the recommendation of the local paint supplier). I think it's called Floetrol.
Tried that but no improvement so I bought yet another brush - a 63mm synthetic bristle Monarch Razorback Oval Cutter for $24.
That seems to have produced a good result but I had to use a new can of Estapol so there is still a possibility the problem was the previous can of Estapol.
I'll try the new brush but with the previous can of Estapol tomorrow and that will identify the problem once and for all.
So far it looks like the brushes I was using were simply too stiff.

Update, again.
No luck (or maybe no skill !)
Still get brush marks. Some parts of the table top were good and others bad so I, yet again, attacked it with the sander with 240 grit to get back to a smooth finish. The next step is to try the "dry" technique already mentioned. I'll apply a thin coat. (The technical data sheet says to apply "generous coats" so that's why I started that way).
Just tried to telephone Wattyl (now Valspar) but they are closed for the day.
This product is really annoying me. I've painted all sorts of things from houses and yachts to furniture over the past 30 years and never had this problem.
There has to be an answer. I don't want anyone else to go through this crap and waste the time I have.
To be continued...

I had exactly the same problem with a Cabots oil based poly and against Cabot's technical dept advice I finished up spraying it, I wasn't concerned with the cost as someone else was paying the bills for the job.