Conversion Varnish HVLP

[marinosr]

I just picked up a can of Lenmar Megavar conversion varnish (standard, not high-solids) for refinishing a dining room table top. It will be my first experience with conversion varnish. I'll be spraying it through a Earlex 5500. Can anyone offer pointers for:

• appropriate thinning (%, lacquer thinner? acetone?)
• needle size
• need for retarder (spraying outside with temps in high 70s, moderate humidity)
• # of coats needed if thinned
• other pointers?

I'm especially hoping that willemjm will chime in because he has noted his experience with this product before. But all comers welcome! I will experiment of course, but I want to start in the right ballpark cause the product is expensive.

 

[Jeff]

I know nothing very little about conversion varnish. You are correct willemjm has used conversion varnish. Here's some information about your product including solvents for thinning and guidelines for thinning.

https://media.benjaminmoore.com/WebServices/prod/assets/production/datasheets/TDS_1M.430X/20190328%201M.430X_TDS%20EN%20OKF.pdf

https://media.benjaminmoore.com/WebServices/prod/assets/production/datasheets/TDS_1A.406/20140902_1A.406_Thinner_TDS_EN_OKF.pdf

 

[marinosr]

Thx Jeff. yes I've read the TDS, but I'm not sure that advice is applicable for a rather low-powered, two stage turbine HVLP setup.

 

[golfdad]

should be able to spray it with the 1.3 tip. Are you spraying multible cabinets?

 

[Willemjm]

I don't have experience with the non-compressed air Aerlex type of equipment. You would have to experiment a little. You need really good atomization with that finish.

That finish dries extremely fast, in the current weather it dries to touch within 10 minutes. So the secret is to get a wet coat with fast gun movement, depositing a wet coat quickly, otherwise you will have a grainy finish.

The first coat always looks terrible, as it balls up on the wood fibers, but it scuff sands better than anything I have ever used. Thin the first coat at least 30% and apply lightly, just to get a wet coat. Second coat goes on nice.

You need a little more precision than pre-cat lacquer, but it is a beautiful finish.

Measure your catalyst in a cup to the right amount and then stir the finish while you add it.

 

[marinosr]

Thx for the very helpful pointers. I think all coats will need to be thinned at least 30% for my gun... hope it doesn't affect the chemistry of the hardening at all. Yes pre-cat is quite forgiving and I'm a bit intimidated, but my 2 young kids require conversion varnish haha.

 

[Willemjm]

Thx for the very helpful pointers. I think all coats will need to be thinned at least 30% for my gun... hope it doesn't affect the chemistry of the hardening at all. Yes pre-cat is quite forgiving and I'm a bit intimidated, but my 2 young kids require conversion varnish haha.

Add the cat before you thin and let it sit for a few minutes. I have sprayed it without thinning and thinned up to 40%, no issues with curing. The more you thin, the easier it sprays.

 

[marinosr]

Very nice results obtained spraying with a light trigger and a 1.5 mm needle, Megavar satin varnish thinned 2:1 with Allpro lacquer thinner, 75F and 60% RH. 4 coats,1h dry time, with 400 grit scuff sanding in between. Thanks for all the pointers! You're right willemjm, it does require more finesse than precat.

Also, it lifted the Teflon off of my cup! Dunno if it was just coincidence, but a big chunk of Teflon floated off the bottom when I dumped out the extra. Annoying, now I need a new cup. Don't know if it was coincidence or if these particular solvents did it.

 

[Willemjm]

I use the Lenmar lacquer thinner, did not want to risk an alternative.

I use disposable cups, a new one for each job, so there is minimal cleaning needed. I suspect the thinner probably reacted with your cup liner.

Pleased to know you had success.

 

[Jeff]

Your lacquer spray finish looks really good Richard.

I suspect the teflon coating on your Earlex cup was faulty. I'd contact Earlex about it.

The lacquer thinners should not affect the teflon coating or its adhesion to the cup interior. I've never had an issue with lacquer thinner or any solvent in my Earlex cup.

Here's the ingredients list for the the Allpro lacquer thinner and the Benjamin Moore Lenmar lacquer thinner.

 

[marinosr]

Contacted Earlex. Apparently the PTFE cup is only for water-based finishes, and they sell an uncoated cup for solvent-based finishes. Good to know.

 

[Jeff]

Contacted Earlex. Apparently the PTFE cup is only for water-based finishes, and they sell an uncoated cup for solvent-based finishes. Good to know.

Good to know. Now I'm not sure if my Earlex cup is uncoated or PTFE.