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justacarp
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Discussion Starter · #1 ·
Hi all,

My first post. Thank you for all the info I have stolen from your site over the years.

I have recently attempted a switch from post cat to wb lacquers.

I have gone through several gallons of the stuff mostly canlak's aqua-syl amongst others and have not been able able to develop a consistent finish and or develop a reliable application schedule.

The biggest problem I have is getting the top coat to flow out with out cratering or developing fish eyes. Haven't yet been able get that just like nitrocellulose flatness that the salesmen are promising.

I have cheated low gloss finishes by minimizing application volume and deliberately leaving a very fine almost dry orange peel rather than apply a full wet coat. The manufacturers have not been a great deal of help and I am going to beat this dead horse one more time.

Method: (best results so far)

Stain (ample dry times over night or better)

Seal with light wet coat (most are self sealing canlak does not offer a wb sanding sealer)

sand 320 (light as possible)

coat 2/3 - shade tone with 10% max of wb stain to lacquer
light to med wet

sand light as possible 320

coat 3 or 4 (Top coat) - light coat as possible barely wet
usually have to block out and apply light almost dry coat to hide the craters.

Application:
HVLP with 1.4mm tip
pot pressure 15 psi
shop temp. 20deg
ambient humidity 35% - 45% (durring time of trials)
out of can viscosity 20-25 sec.
Vertical application when possible


Guaranteed failures achieved through experience:

Reducing more than 5% (fisheyes)
Adding flowetrol or other wb retarders (greys/hazes)
applying more than 4 thin coats or any thick coats (craters you can loose change in)
Reducing with acetone
shop temp below 15 deg
2 mm tip
1 mm tip
wet on wet application
warming paint pots

So if you guys have any more ideas I would love to hear the ones that work and yes my guns and substrates are clean.
 

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Old School
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In temperatures like that, it will dry, but take longer.

Thin your waterbase polyurethane with water, not acetone. Sounds like your media is too thick. Start with about 5%...½" in the bottom of a 1 qt cup. The more you add the better it will lay down.

Work with extra light so you can get a glare on your spray paths.

Experiment with air/fluid mix. Gun should be at about 12lbsPSI to 15lbs PSI, and airline to the gun about 30PSI to 35PSI. These are approximate figures.

Your path should be slow enough to be "wet", along with a pattern wide enough to provide overlaps, but not too wide to allow misting, or a rough dry application.

Moving too fast, or too far from the subject can cause the roughness. If you are getting "fisheyes", you may have some contamination in the gun, airlines, tank, on the subject, or ambient in the spray area.

I would not sand the first or second application. I would use 320x open coat sandpaper between applications.










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I take it you mean 20 degrees Celsius which is 68 degrees Fahrenheit which is warm enough to spray the wb lacquer. If you do mean Fahrenheit that is just too cold for any water based finish. I would go back to the post cat lacquer until the weather warms up. The cratering could be attributed to some substance on the surface such as if you are using stearated sandpaper between coats. It works alright for your solvent based lacquer but the water based stuff is a different critter. Your stain if it is oil based can be causing you some trouble too. The linseed oil in stains is incompatable with water based polyurethane so it might be a good idea to seal the wood with Zinsser Sealcoat before using a water based lacquer topcoat. The shade tone you are using, is it compatible with the lacquer you are using?
 

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Old School
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The linseed oil in stains is incompatable with water based polyurethane so it might be a good idea to seal the wood with Zinsser Sealcoat before using a water based lacquer topcoat.
Once the oil base stain has dried, water based polyurethane can be applied as a topcoat. No Sealcoat is needed.






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Once the oil base stain has dried, water based polyurethane can be applied as a topcoat. No Sealcoat is needed.






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It should read once an oil base stain has dried three days to a week Sealcoat isn't necessary. I don't know of anyone that is that patient. The Sealcoat will bond to wood which has been stained a few hours prior and the water base lacquer will bond to the Sealcoat. Win Win
 

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Old School
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It should read once an oil base stain has dried three days to a week Sealcoat isn't necessary. I don't know of anyone that is that patient. The Sealcoat will bond to wood which has been stained a few hours prior and the water base lacquer will bond to the Sealcoat. Win Win
Lose, lose. IMO, trapping the stain when it's not dry creates a poor base for a topcoat, if you aren't concerned with the finish. Depending on the temperature and humidity, an oil base stain applied properly...wipe on...wipe off, is usually dry in a day or less.




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justacarp
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Discussion Starter · #7 · (Edited)
Thank you all

For clarification:

Temp is in Celsius. Warming the shop further at this time of the year is not feasible.

Sanding on primary coats is kept to bare minimum to remove any roughness. Dry material is so thin that burn through is a definite concern and high build is impossible. The more material you build up on the substrate the worse the pitting becomes. Open coat paper has been used.

I have run the material with both a turbine and compressor at multiple settings and with different guns (document and adjust method) (minimal difference in results)

Reducing with ambient temp tap water more than 5% results if fish eyes

Reducing with acetone was a wild shot in the dark that failed miserably.

I have run stain samples with both solvent (goudey) and wb stains (saman) using dry times for different sample sets from 2 hrs to 24 hrs. adhesion is good with both bases and does not seen to be the root of the problem.

Shade tone has been done with the wb. Colours are excellent, clairity is good at higher end of gloss scale, adhere, mix and flow well. Mix at above 10% colour to lac. fisheyes. The colour/pigment seems to retard the drying an d help flow process better than water. (need to research the chemistry to find out why)

I have been diligent in my cleaning and have not used silicone or epoxies in the shop in months.

I am at the point where I doubt the material more than I doubt my skill and research.


I will try the sealer and see if there is a diffidence.
 

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Lose, lose. IMO, trapping the stain when it's not dry creates a poor base for a topcoat, if you aren't concerned with the finish. Depending on the temperature and humidity, an oil base stain applied properly...wipe on...wipe off, is usually dry in a day or less.






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You don't get it. The linseed oil in stain will dry enough in a day or less if you are using shellac, lacquers or oil based finishes over the top and it will cure under the finish in time. The linseed oil needs to be fully cured for water based polyurethane to properly adhere. Linseed oil is incompatible with water based polyurethane and at least once a year I have to refinish something another painter has done because they applied water based poly over stained wood after just overnight drying.
 

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Old School
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You don't get it. The linseed oil in stain will dry enough in a day or less if you are using shellac, lacquers or oil based finishes over the top and it will cure under the finish in time. The linseed oil needs to be fully cured for water based polyurethane to properly adhere. Linseed oil is incompatible with water based polyurethane and at least once a year I have to refinish something another painter has done because they applied water based poly over stained wood after just overnight drying.
Arguing won't make anything right. If you think you're right, that's your opinion. Your story reminds me of the refinishes I've done because the Sealcoat peeled due to it being applied over an oil stain that wasn't cured.:yes:






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justacarp
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Discussion Starter · #10 ·
I have looked at msds on the seal coat.

Use of an alcohol base seal coat negates the reasons for attempting a switch from post cat to wb. (flamabilty, insurance costs, fire inspection, increased storage and disposal cost and the hang over associated with solvents)


As stated previously the is no difference in the top coat when laid over solvent base or water based stains (months have passed). The fact is the top coat lays down inconsistently. What is consistent is the cratering.
 

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Old School
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I have looked at msds on the seal coat.

Use of an alcohol base seal coat negates the reasons for attempting a switch from post cat to wb. (flamabilty, insurance costs, fire inspection, increased storage and disposal cost and the hang over associated with solvents)


As stated previously the is no difference in the top coat when laid over solvent base or water based stains (months have passed). The fact is the top coat lays down inconsistently. What is consistent is the cratering.
The info I suggested in Post #2 (the air pressure was for HVLP). You might try a siphon cup and gun. If you tried the suggestions, go to more thinning as an experiment. Give 25% water a try. There is no reason for cratering/roughness for a diluted mix like that. No reason for fisheyes either.






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justacarp
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Discussion Starter · #12 ·
As per previous clarification above. The more this stuff is reduced the worse it lays. (almost like it is stringy) Other wb coatings react the way you have suggested (I know varethane does) but this stuff does not. I don't claim to have a lot wb experience. Have you ever put down a wb finish that compares to nitro? I have seen it done but cant seem to find the people who have done it.

The fisheyes I am trying to describe look like the reducing water and the finish are separating on contact with the subtrate.
 

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Old School
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As per previous clarification above. The more this stuff is reduced the worse it lays. (almost like it is stringy) Other wb coatings react the way you have suggested (I know varethane does) but this stuff does not. I don't claim to have a lot wb experience. Have you ever put down a wb finish that compares to nitro? I have seen it done but cant seem to find the people who have done it.

The fisheyes I am trying to describe look like the reducing water and the finish are separating on contact with the subtrate.
Sounds like a bad batch. Could be contamination, old stock, junk in the gun. Hard to tell. I spray out of a siphon gun, and it comes out like glass. When you fiddle with any and all possibilities for gun/air adjustments, you should hit on a winner. Try another brand. Minwax Polycrylic is about the most basic WB poly, and it's easy to shoot...very forgiving. Also available at HD is a WB poly called Parks Pro Finisher that's great for flooring, and IMO, is as durable as nitro. Also easy to shoot.

When you use a compressor and a gun, what compressor is it, and what gun(s)?






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justacarp
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Discussion Starter · #14 ·
compressor is made by devilbiss
Guns are lemmer and gracco (the model #s escape me)
I have moved away from the compressor guns because I have forgotten to drain the tank in the past and ended up stripping the finish to save the piece.

Gun vomit with wbs is another problem but is instantly recognizable and the source is usually semi dried accumulation at the tip.



All in I think all the fiddling has been fiddled out. Time to move on to a different product. Thanks for your help and suggestions.


I have tried some of the common pollies in the past but they seemed to have their own sets of problems ie. turning opaque or graying overtime, poor water resistance once fully cured among others. Have you had any issues with the items you have listed above?
 

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I agree with all Steve said. The stearates in sandpaper can be a real problem even with a light sand.

Keep your coats real thin they tend to look bad but level out once dry.

Good luck with WB if not using compressed air with a 1.3 tip in the gun. Atomization is very important.

Google Target Coatings and give Jeff a call IMHO they are miles ahead of anyone else with WB. It sounds as if there is an additive depleted or old stock with the material.

You can beat the durability with WB Lacquer event better than catalysed but good luck with achieving the look and hand feel of our good old solvent based finishes.
 

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Another maybe in this is your compressor may be dispensing oil with the air causing something similar to silicone fisheye. You might take a air nozzle and spray air through a clean white cloth and see if there is any presence of oil. The finish thinned or not should spray alright. I think there is an unknown substance causing the finish not to flow out.
 

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I'm going to add my 2 cents worth, but qualify it by saying that I haven't been able to produce consistent results with WB Lacquer.

I've used Grafted Coatings' KTM 10 which when buffed looks better than nitro IMHO. It has incredible clarity and depth. However, if you let it dry too long, it is very difficult to rub out. I think WB is very tempermental about temperature and humidity. I have had some success with warming the finish before shooting. I use the Devilbiss 9oz D-Kups and put the cup in hot water, changing to new hot water periodically to ensure the finish gets warmed all the way through. It doesn't take much with the small cups. Warming it seems to lower the viscosity. Thinning with water seems to mess up the chemistry of the finish and produce really inconsistent results. Heating the finish only goes so far though if the board it's getting sprayed onto is a radically different temperature.

My latest problem is that I'm getting lots of Micro bubbles in my finish. I think it's that I'm applying to thick, but that's hard not to do when spraying relatively thick finishes. If anyone has some experience and solutions for this one, I'd really appreciate it.

I'd love to keep this thread going. Maybe if we all test and contribute we can all solve one another's WB problems. That would be a huge bonus for me, because for me, nitro really isn't an option.
 

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My latest problem is that I'm getting lots of Micro bubbles in my finish. I think it's that I'm applying to thick, but that's hard not to do when spraying relatively thick finishes. If anyone has some experience and solutions for this one, I'd really appreciate it.

I'd love to keep this thread going. Maybe if we all test and contribute we can all solve one another's WB problems. That would be a huge bonus for me, because for me, nitro really isn't an option.
Correct, micro bubbles is too thick a coat, the vapors gets trapped. With WB the coat does not need that much of a wet coat appearance compared to solvent as it levels out more while drying. Also helps if the surface being sprayed is not horizontal.
 

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It makes sense that the thickness traps bubbles. Thanks for that insight. What's the best way to spray a lighter coat?

Should I lower material flow, or increase the distance from the gun to the surface? Or something else?
 
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