General Finishes Conversion Varnish pot life problem

[scott vroom]

Just bought my first gallon of GF WB conversion varnish. They say it has a pot life of 6-8 hours but I experienced a much shorter useful life. Yesterday at 2:00 PM I mixed a pint + 10% catalyst in the spray cup using a mixer on my drill. Let stand for 10 mins per instructions. Sprayed my work piece; after 90 minutes I sanded and re-coated. After another 90 mins sanded and sprayed a third coat. This is where i had the problem. The HVLP spray began sputtering as if the cup was low, which it wasn't. Put the cup back on the sprayer and tried to finish up but the sputtering got worse and it began laying down big drops...I stopped immediately and took a close look at the gun. What I noticed was a thick goo on the strainer that was preventing an adequate supply of varnish to enter the feed tube. This was about 3-1/2 hours after adding the catalyst. This morning I had to sand down the entire piece to get the globs off and am about to mix another batch. I called GF and they didn't have a good answer.

This is a relatively new GF product and I'm wondering if anyone else has tried it and if so had a similar experience (short pot life).

[David Hawxhurst]

i've had similar problems with pot life with a different product. in my case it was the catalyst. believe it was drying out or to old.

at what temp did GF use to determine pot life? higher temps usually shorten pot life.

[scott vroom]

David, I don't see where GF specs pot life temp. Yesterday it was about 75 degrees in my shop MOL. I'm liking the super hard finish from the CV but am not liking a 3+ hour pot life. If you want to do 3 coats it's a risk. So the approach would be to mix smaller batches more frequently, except that I'll end up throwing more away since the HVLP bottom cup never fully drains. Maybe this would be a good time to get a top gravity feed cup?

[David Hawxhurst]

i would call GF tech and ask them what temp they test the pot life at. my guess would be ~70 degrees, but at 75 you should have pretty close to there stated pot life. they should help you solve this problem or replace it. if you what i can give the part numbers for a solvent 2k urethane that is a little cheaper than the GF. the price is the main reason i haven't tried the GF CV.

how about 3m pps? i switched to it and like it a lot. do you have a pressure fed cup or suction type? 3m makes both types in pps, ho type are for pressure fed and come in two sizes. i think the non pressure fed comes in two or three sizes.

[scott vroom]

i would call GF tech and ask them what temp they test the pot life at. my guess would be ~70 degrees, but at 75 you should have pretty close to there stated pot life. they should help you solve this problem or replace it. if you what i can give the part numbers for a solvent 2k urethane that is a little cheaper than the GF. the price is the main reason i haven't tried the GF CV.

how about 3m pps? i switched to it and like it a lot. do you have a pressure fed cup or suction type? 3m makes both types in pps, ho type are for pressure fed and come in two sizes. i think the non pressure fed comes in two or three sizes.

I'm trying to stay WB. On the GF price, yeah even with my discount I think I paid north of $100 for the CV + Cat. Ouch. But after 24 hours the stuff is hard...and will probably get even harder. Project is a desktop slab so a hard finish is highly desirable.

[Brian W Smith]

Scott,the two things that got me started with "top loaders"(gravity guns),25 or so years ago was mixing small batches and cleaning.We had some pretty nice bottom loaders(siphon) too,so it came with a bit of trepidation.I don't see us going back to siphon,will break out the old Binks pressure pot before that.

>Mixing sm. batches;we get them from wally world.....they're mixing "glasses" intended for home bars?They are 150 ml....5 oz.Made of glass,and have very easy to read lines.Get a 1/2 dz or so.On the gun side,you can get small "cups" to go on full size guns.....needs an easy to make adapter.

>Cleaning;Back to wally world,but just as a reference/looksee,haha.The best thing we've found for cleaning guns is a flip-top,kitchen trashcan......in Stainless steel.Ours came as a freeby 'cause the foot operated lift mech. was broken.It most deffinately didn't come from wally world.....a customer gave it to me.Anyway,it's the "full-size" can,takes std kitchen plastic bags.Being pretty air tight it is as safe of a way to dispose of cleaning agents as we've found.

Won't go into too many details but,they work top shelf if you put a nozzle port in the cans top(simple plastic stopper to fill hole when you aren't using it) for gun cleaning.On a top loader it only takes a cpl bursts to somewhat clear the tip,then you just tie back the trigger and let the cleaner run through(no air at this point).Pull bag and dispose at the end of the day,spraying.Put it this way,the flip top SS can is so convenient that we don't even think to clean guns out the shop's back door anymore.This can is only used for "stuff" that is paint related,nasty rags N such....it is not used for general trash purposes.

On another note,we use Argon in our more expensive paints/clears/hardeners to displace oxygen.......material costs,can't afford to not preserve them?

[David Hawxhurst]

WB stuff can be pretty expensive when your talking about the really good ones. all the 2 part finishes i'm familiar with dry very quick and often times can be placed into to use after 24hrs (although most have a 7 day for full cure). as for the pricing the best i've seen come out to be ~$120ish plus shipping for the gallon kit.

[scott vroom]

WB stuff can be pretty expensive when your talking about the really good ones. all the 2 part finishes i'm familiar with dry very quick and often times can be placed into to use after 24hrs (although most have a 7 day for full cure). as for the pricing the best i've seen come out to be ~$120ish plus shipping for the gallon kit.

Yep...that's the retail pricing I'm seeing as well. I get a 20% discount from my distributor and am still wondering if it's worth it. I've used GF clear poly for years and have found it more than adequate for cabinets, but current project is a desktop that will get some abuse so spent the $ on the CV. One big downside to the CV is that it doesn't touch up well. I had a small particulate after a coat...sanded it out and sprayed that spot....it stuck out like a sore thumb so had to sand entire top and re-spray. PITA...but my bad for the particulate. Enduro clear poly touch ups blend well.

Edit: That next coat didn't go well. I laid down even, overlapped passes but when it dried there were dry looking areas (i.e., flat finish...and I'm using satin). This should not have happened since I've already got 4 coats beneath it so no effect from wood soaking up the finish. I'll do another coat to try fixing it. Could be my skill level isn't equal to the task, but I'm finding this stuff much more problematic that poly and frankly for the cost of the CV it's not worth it. If the next coat doesn't yield a pristine finish I'm going to cut my losses and overlay with Enduro Poly.

Are there other brands of WB CV that might be easier to work with?

[scott vroom]

Last 2 coats went down well....but only because I layed it on thick enough for the CV to show it's milk white color. Nevertheless, I'm reasonably satisfied and am done....will let the desktop slab cure in the shop for a few days before installing onto the cab lowers. Here's a pic taken in crappy light but you get the idea.

[scott vroom]

New project, same pot life problem. Today I poured 12 oz of GF Conversion Varnish into a pyrex measuring cup and added 1.2oz of catalyst and stirred it up....maybe 2 mins? When I poured the mixture into the spray pot it was a bit goopy....like it was already beginning to harden. I tried spraying it on a sample board and got major orange peel with spots sputtered about. Opened the spray pot and sure enough the filter was clogged with a thick paste...obviously the result of premature hardening. I called my distributor and he referred me to a chemist at GF whom I'll call tomorrow.

I ended up laying down Enduro Clear Poly on the desk top slab...not as hard as the CV but good enough for a light duty desk.

I'll update this thread after speaking with GF.

[scott vroom]

Spoke this morning with Adam, one of the chemists at GF Troy. I described my process of adding 3 tablespoons of catalyst to the varnish and then stirring. He knew right away what the problem was: With WB conversion varnish it's critical to be stirring the varnish when adding the catalyst otherwise the coagulation will begin just seconds after adding catalyst....the chemical reaction is that fast. I told him that nowhere on the can or the catalyst bottle was this mentioned. I believe he said that they've since changed the label directions.

Without my having to ask, he offered to ship me a fresh gallon and bottle of catalyst gratis.

I also asked him if I should expect a properly mixed batch of conversion varnish to lay down as nicely as their Enduro Clear Poly.....he said no due to the rapid drying of the CV resins.....it just doesn't have the time to flow out like the Enduro.

Anyways, GF continues to show they care about even small customers....makes we wanna keep using their products.

[John TenEyck]

Thanks a lot Scott for documenting your efforts with the Enduro CV. I've thought about using it a couple of times, but have yet to actually do so. Not sure I want to after reading about your problems, and the fact that it won't lay down as nice as Enduro Clear Poly even if mixed like the now say it has to be. Nice to see GF offered to replace the finish, it helps take away some of the sting, but it would have been better had they had the proper directions on the can to begin with.

Oh, did you ask him about the pot life if the catalyst is added correctly?

John

[scott vroom]

Thanks a lot Scott for documenting your efforts with the Enduro CV. I've thought about using it a couple of times, but have yet to actually do so. Not sure I want to after reading about your problems, and the fact that it won't lay down as nice as Enduro Clear Poly even if mixed like the now say it has to be. Nice to see GF offered to replace the finish, it helps take away some of the sting, but it would have been better had they had the proper directions on the can to begin with.

Oh, did you ask him about the pot life if the catalyst is added correctly?

John

John, I didn't ask him about pot life although they advertise 6-8 hours on the can label (temperature sensitive). I've let properly mixed CV sit in the cup maybe 3-4 hours w/out issues. I've got a free replacement gallon coming and will likely use it again on work surface projects such as high-use desktops...but my go-to WB tough finish is still Enduro.

[John TenEyck]

Yep, Enduro Clear Poly is my favorite finish, too. Sprays like a dream and gives a great looking, hard wearing finish.

Johnn

[Jeff McMullin]

Spoke this morning with Adam, one of the chemists at GF Troy. I described my process of adding 3 tablespoons of catalyst to the varnish and then stirring. He knew right away what the problem was: With WB conversion varnish it's critical to be stirring the varnish when adding the catalyst otherwise the coagulation will begin just seconds after adding catalyst....the chemical reaction is that fast. I told him that nowhere on the can or the catalyst bottle was this mentioned. I believe he said that they've since changed the label directions.

Without my having to ask, he offered to ship me a fresh gallon and bottle of catalyst gratis.

I also asked him if I should expect a properly mixed batch of conversion varnish to lay down as nicely as their Enduro Clear Poly.....he said no due to the rapid drying of the CV resins.....it just doesn't have the time to flow out like the Enduro.

Anyways, GF continues to show they care about even small customers....makes we wanna keep using their products.

Scott, I am having a similar problem with general conversion varnish--purple label. Upon adding the catalyst and stirring, the solution got all gloppy. Test sprayed on the wall and there's white glop everywhere. Thank goodness I didn't shoot my countertop with many many hours of sanding invested. Can you put me in touch with the chemist in Troy? I'm out $150 with shipping.
Thanks,
Jeff