General Finishes Conversion Varnish

[Mark Gibney]

I’m thinking of spraying GF conversion varnish on some tables. However, a vendor showed me a plywood section coated with this product that feels grippy, almost a little rubbery compared to the hard smooth feel of WB “polyurethane”. I was surprised, and I’m hoping he got his samples mixed up.

Is this how GF conversion varnish feels?
I’d prefer a hard smooth finish for these projects.

Also, I’ve read the conversion varnish is stronger and “better” than the WB poly. Is it?
Is the difference noticeable?

Thanks, Mark

[John TenEyck]

I've never used conversion varnish, but I've run my hand across lots of tables that have been coated with it, thought not GF's, and the finish was always hard and smooth. If the GF product you saw didn't feel that way I think something was out of whack. In any case, conversion varnish is indeed a much more durable finish than WB, or OB varnish, polyurethane or otherwise. It's a catalyzed finish which makes it much more resistant to chemicals than products that cure through simple oxidation.

I've read that GF's conversion varnish is pretty finicky in how you add the catalyst, and that the catalyst is a real health and safety concern.

John

[Jim Becker]

I'm not familiar with the GF product, but I have used the Target Coatings EM8000cv on two projects (a very large kitchen island/continent top and my own kitchen upper cabinets) and there's no feeling of "grip" to me. It's just smooth and "feels" hard.

[John TenEyck]

I wonder if the sample you were shown was GF's Exterior 450. That product is designed for exterior furniture/doors, etc. and it is definitely soft and grippy for a long time.

John

[Wayne Lomman]

2 part coatings are significantly more durable as John has pointed out. The sample you were shown does not seem correct. Go somewhere else and see a sample.

As far as safety is concerned, wearing a respirator is a given and provides the necessary breathing protection. The catalyst is hazardous but the technology has been around for long enough that the hazards and controls are well documented and simple to implement. This is not the case with newer coating technologies where we are still the lab rats unless we use decent quality protection. Water borne does not equal safe.

With mixing, follow the ratios strictly and remember pot life is temp and RH dependant. Cheers

[Jamie Buxton]

GF's "Conversion Varnish" might better be called a two-component urethane, because the catalyst is based on isocyanates. I'm not enough of a chemist to tell you exactly what those are, but evidently they are not good for the human body. You can do your own digging about them. One thing which concerns me is that I have not been able to find a respirator manufacturer that certifies any filter cartridge to protect against isocyanates. Some just omit isocyanates from the list of chemicals their filters work on, and some explicitly say they do not protect against isocyanates. OHSA says that the people spraying 2K urethanes must work in a certified paint booth (to protect the environment), and must be breathing clean air piped in from outside. The products I've seen for piping air in from outside have the painter wearing a hazmat hood. Perhaps you can dodge around the certified booth if you have no close neighbors, but I'd think very carefully about protecting my own lungs.

[Tom M King]

Having a beard, I use supplied air a lot. Mine is kind of low tech though. I use the disposable Tyvek hoods, that sell for about 25 bucks. They last a long time until the last clear face part gets so it obstructs vision. That hood also comes with a belt, and short hose attached, so you need that version to start with, and then you can buy the hood alone that clips to the hose with a fast disconnect zip tie. Adapted to that hose, I use a couple of blue, long Shop Vac hoses, just because they're a different color than our other vacuum hoses, and never want dust sucked through one.

The belt keeps it from blowing off your head.

I thought about using a small Shop Vac for the air supply, but was never sure there wouldn't be some oil coming along with the air, so I tried a turbine from a spraying rig. That worked, but one thing they don't tell you about those is that they heat up the air. That didn't work in hot weather, so that led me to think about using a small, 110v air conditioner. The little AC works like a champ, and has an extra bonus in hot weather. The AC sits in clean air, and pulls it through a clean filter before sending it down the line. You have to dump some of the air before it enters the hose, but I never get dust in my nose, and sleep well.

Here's a picture with me cutting old plaster with it on.

I even used it once for airless spraying Moisture Cure Urethane white paint on a small airplane hanger floor. If you look on a toxic solvent chart, that stuff has every one listed on the chart in it, except for gasoline.

[Wayne Lomman]

Yes, urethane spraying is hazardous if you cut corners. However, the health hazards are well documented and understood. Simple protection such as Tom shows provides everything you need. The overspray is only hazardous until the curing is underway and the isocyanate is no longer free. At this stage it becomes polyurethane which is one of the safest plastics and is used extensively for food and water contact. I recommend it all the time because it is well researched and we know what it does and we know how to protect ourselves.

One further point to consider is to study the volume solids of what you are spraying. This GF product is about 28% solids which is woefully low. Look for a decent one in the 50-60% solids range. You only need to spray half as much to get the same film build and it is cheaper per square metre to apply as a result. There are more ways to reduce hazard than reading chemical labels and you save a buck at the same time. Cheers

[Mark Gibney]

Wow! That's a lot to think about now. I actually did presume that water based meant it would be more or less benign.
Thanks for the wake up.

Tom, I like your protection clothing you rigged up.
Everyone, thank you for your informed opinions.

Mark

[Jim Becker]

Mark, water borne (not water based) finishes can still have health and environmental effects. The water is primarily the carrier; it's not the solvent. The actual finish, including it's solvent, just goes along for the ride in the water and as the water flashes off, the finish begins to coalesce into the, um...finish. :) That said, it comes down to the specific finish project. "Most" are pretty benign at this point and simple personal respiration and ventilation is adequate. But there are still some that have VOC and other factors that need to be taken into consideration.

[Tom M King]

Anyone interested in the low tech supplied air setup, do a google search for: , and that's the starting point. Once you have that, replacements for the Tyvek part alone are only a little over 20 bucks, but I end up using them for a couple of years sometimes. You do get used to dragging a tail around. : ALLEGRO TYVEK SUPPLIED AIR RESPIRATOR (SAR) HOOD ASSEMBLY 9910

[Wayne Lomman]

Hazards for new materials only really get found out over time at the expense of user health. Think of sand for blasting, lead, asbestos, DDT, 2-4-D, 2-4-5-T etc etc. These used to be common products you just purchased anywhere. Polyurethane was found out the same way but the controls are simple and you only need a good inventor like Tom and those controls don't even cost much so we can still use it.

Every new chemical or whatever that is released on the market has the potential to be another one of these. We hope not and it is probably less likely than it one was. The least we can do is follow the basic safety procedures and never assume it is going to be safe unless it has at least a lifetime of historical data to back up its claims. Just ask my daughter how safe 2-4-5-T is for the next generation. Cheers

[Mark Gibney]

I’m sorry Wayne. I hope nothing tragic happened with you daughter.
There have been bad outcomes in my family that are related, as far as we can discern, to glyphosphate.