Follow-up Question Spraying Conversion Varnish

[Scott Bernstein]

I will be spraying the inside of my kitchen cabinets with waterborne General Finishes conversion varnish, satin. They are Baltic Birch plywood, with solid poplar edge banding, european style - no face frame. I am building the cabinets now and hopefully will be done and ready to start finishing by the spring, when it is a little warmer. Estimated dry time to re-coat is 2 hours and pot life is 6-8 hours. I am quite a novice with spray finishing. Can I let the the spray gun rest between coats of conversion varnish? Or do I need to completely clean and disassemble it between coats to prevent the varnish from curing in the gun?

Thanks
Scott B

[Prashun Patel]

I can't speak to GF's product, but I've used Target's conversion varnish (EM8000cv). I leave it in the gun overnight and it's just fine. I used the cross linker which is supposed to increase chemical resistance at the expense of decreased pot life. However, I have used product a MONTH after adding the CL and it worked fine.

I have left the product in the gun even over night and it has sprayed ok. However, it can clog the gun just enough to make it sputter. You may not even notice it on a satin or flat sheen. I have also noticed that these waterbased finishes can leave a blue cast. I get this worst when spraying too thick a coat, and then doing too many coats in a row; it's tempting because it dries so fast.

So, my practice now is like this:

Spray three coats at the suggested mil thickness about two hours apart. I don't clean the gun in between.
After the 3rd coat, I let the piece dry overnight. Then I clean the gun by running water into it, keeping the trigger depressed and letting it run until the water runs clear and free. This allows me to keep the flow and fan settings constant.
Next day, repeat as needed.

[John TenEyck]

TC's Crosslinker, after mixing with the topcoat, an be left in a covered container for at least 100 hours w/o issue according to TC. They don't say what happens after that, however but that should be more than enough time to use the batch.

John

EMTECH CL100 CrossLinker is a water soluble chemical additive used to elevate the durability and appearance of waterborne coatings by coupling the resin molecules of the film forming finish into tighter, harder bonds when fully cured. The purpose of CL100 water soluble CrossLinker is to give a performance boost to the physical characteristics of the finish it is being blended into.
Although rarely necessary in most wood finishing applications, sometimes a specific finishing scenario calls for extra alcohol or detergent resistance. For instance, commercial bar tops and restaurant tables receive a lot of chemical abuse from both the patrons and the cleaning staff. The addition of 3-5% of CL100 CrossLinker into the waterborne finish of choice will boost the coatings resistance to alcohols and high pH cleaners to levels that will allow the cured finish to withstand a longer exposure to corrosive chemicals. Unlike acid catalysts, which have a very short pot-life, waterborne cross-linkers are reactive to oxygen only when the coating it is added to is allowed to form a film and air-dry. Therefore, the pot life of finishes fortified with CL100 water soluble CrossLinker will remain functional for upwards of 100+ hours when stored in a sealed container, eliminating the expensive loss and waste of unused material.
EMTECH CL100 CrossLinker improves the following physical characteristics and visual effects of the coating it is being added into:

• Through-cure time
• Gloss/sheen
• Water and alcohol resistance
• Scuff & mar resistance

[Scott Bernstein]

Well, OK. Maybe next time I'll try the Target Products. But for now, given the GF has a much shorter pot life I think I will need to rinse the gun between coatings. Is water adequate for that? What is the best thinner/cleaner to use for GF's enduro 2k conversion varnish?

Thanks!
Scott B

[Prashun Patel]

Didn't mean to say you need to use the Target.

I've used Enduro Clear Poly a bunch and I find you can use water to clean it just fine. I suspect it's the same for their Conversion varnish.

[John TenEyck]

GF's data sheet says soap and water to wash it off. It also says to use their gun cleaner to clean your gun, but they say that on all their products. I use soap and water with my gun, and soak the nozzle and air cap in lacquer thinner after to make sure they are clean. I think the key with conversion varnish is to make sure the gun is clean before it sets up. If that happens the gun is likely toast.

John