Does anyone use waterborne lacquers?

[Cutting Crew]

Hi all,

In an attempt to get rid of nasty smelly cellulose lacquers I'm trying waterborne sanding sealer and lacquer on some larger turned pieces, has anyone on the forum tried these lacquers on their own projects?

I mainly apply my other lacquers by spraying with an HVLP gun and, I'm really not sure if waterborne lacquers dry by chemical reaction or evaporation, so I don't know if using warm water as a dilutant will help.

CC

 

[Chris Knight]

CC,

I spray these a lot. I have used three types of gun (turbine HVLP, a conversion gun type HVLP and a regular gun). Any of these work fine.

First things first - don't dilute these things unless it is absolutely necessary. They will only tolerate a very small dilution (<5%) and it makes them temperamental. Pick a needle/nozzle combination that will handle the undiluted material.

Don't spray when it is below about 15 degrees.

They dry very, very fast and it is easy to get a dry coat when spraying (that horrible sandy feel), so practice first on a bit of cardboard or something. Also, for this reason, you have to be very careful of inside corners in eg a cabinet with its back on. Try to do as much as possible before assembly. Apply the spray evenly with a good wet coat and don't worry too much about the blue colour(!) - it disappears.

On square edged material (like shelves) do spray the arrises first.

Most of these coatings benefit from applying the coats as quickly as possible (eg spray next coat after the first is touch dry, this way the coats seem to bond together much better. If you have to leave a significant interval before applying a second coat, do any sanding that is needed before applying the next coat (there are usually instructions concerning this)

You still need to use a mask and cover anything you don't want absolutely covered in a very fine white dust (dried spray). It brushes off most things because it's dry when it lands but things closer to the action may get hit with wet spray and it will stick.

This stuff is still a chemical, it cures through a chemical reaction, not by evaporation - very different from nitro or shellac in this regard. Secondary coats do not dissolve into the first with all that that implies.

 

[Cutting Crew]

Hi Chris,

Thanks for the help, a much clearer explanation than all the information sheets my supplier puts out.

I've just spent the last two days with my new waterborne finish and to say the least I'm impressed, no smell, easy clean up and few hazards.

On the first day I tried the sanding sealer, this was easy to use and had good results, slightly thinned the first coat and sprayed a second coat as it comes. I couldn't believe the drying times, my spec sheets quoted 30 minutes to touch dry and recoat in 2 hours, being impatient I tried your way and was recoating inside 30 minutes.

Day two saw the gloss waterborne, I had a few problems here, the worst one I had was with 'fish-eyes'. Although I used the same gun as with the sealer, I guess I must have picked up some contamination along the line somewhere. I think the other problems came with the damper colder weather. I eventually got most of the problems sorted and again was very impressed with the results.

On my gallery and exhibition work I wet sand and finally use a buffing system to give the surface finish I'm looking for, sometimes gloss, sometimes satin. When I spray with cellulose, I normally leave the pieces about a week to fully cure and harden off, I tried one of the pieces finished earlier that day expecting the lacquer to pull off or at least scuff as cellulose can do, but it didn't, indicating the waterborne lacquer is at least as tough as the cellulose and probably quite a bit tougher.

Thanks again.

CC

 

[Chris Knight]

CC,

I rub out/buff these finishes too but be careful - it is not like nitrocellulose. Each coat of waterborne is a separate layer and any deficiencies in coverage can reveal themselves during buffing, usually by a bloom or whitish look as your compound or fines from the sanding operation get behind the top layer of finish in places where it is cut through. Also whilst they are indeed tough finishes they never get as hard as a nitro or shellac, exhibiting more elasticity - and the harder finishes always rub out better than soft finishes. I have left them anything from 2 days to a couple of months before rubbing out and there is in my experience not a huge difference in results.

Here is a surface I buffed out after three days

 

[Cutting Crew]

Hi Chris,

Checking under a brighter light I can see what you mean about the coats seperating, I found a couple of the small white marks where I had cut through.

Do you have any knowledge of Polyurethane?

Thanks again for the help.

CC