Compatibility of Solventborne and Waterborne Formulas

      A conversation about the feasibility of using solventborne dyes, a vinyl sanding sealer, and a waterborne topcoat on a single piece. April 17, 2010

Question
I am looking to use a hybrid system using a vinyl sealer over oil base stains then glaze with a second coat of vinyl sealer and top coating with Valspar Zennith waterborne precat. Has anyone been using this type of system?

Forum Responses
(Finishing Forum)
From contributor F:
It will work. Your main issues to deal with and to worry about are durability/integrity of the overall film, intercoat adhesion, how to deal with sand-throughs and witness lines of your different finish films and respecting the dry and cure times of each finish type.

If something goes wrong with your coating and you need tech support, you're on your own unless you're a major manufacturer who already has on hand reps from each finish manufacturer and the like in your factory or factories. These large producers of durable goods get the benefit of maverick finish systems and accompanying tech support from competing finish reps using hybridized finish systems like what you want to lay down.

You need to perform proper scratch tests, testing intercoat adhesion with each finish step using a bonafide scratch test adhesion tool and not the not-so-scientific razor blade and masking tape tests. You also need proper pencil test hardness tests (done after 30 days of full cure) for your topcoats to see how well or how poorly your maverick finish stands up to marrs and scratches. Do not warranty your finish in any way unless you like cans of worms and pandora's boxes and invitations for trouble.



From contributor C:
Is your vinyl also a precat??


From contributor A:
Why are you using a 90% solvent schedule then switching to a wb topcoat?


From contributor O:
Your coating schedule should work. It depends a lot on what kind of wear the surface will take. I agree that you're on your own technically, for the most part, but I think one thing to be careful about is to let the final coat of vinyl sealer cure for 24 hours so that it can seal as much as possible.

I think that a complete waterborne system to replace your oil-based stains is available and if you convert to it then there's no worry about the vinyl barrier. We've switched over to H2O completely and itís much simpler than running a hybrid system. That's not meant as a criticism of your idea which might well work best for you but staining and glazing with waterborne products can be done without a compromise in quality or a new skill set.



From contributor F:
Hybrid systems are increasingly popular for a number of reasons. First and foremost is color matching. While water based systems as a whole have seen vast improvement in recent years, the stains are still the weak link in trying to go completely water base.

Workability and color vibrancy are still an issue with water based wiping stains in my opinion. It's not impossible to match colors in a completely WB system but it's not easy either and if you are trying to match a stain that was done in a solvent it may well prove to be challenging at best to reproduce the exact look in a WB stain. Dyes help but WB dyes will raise the grain considerably.

Other reasons for considering a hybrid system are dry time and being able to offer a somewhat greener finish system while not having to commit totally to water base. It will let you ease into water base instead of having to dive in head first. Having said all that, make sure the Vinyl Sealer you are using is approved for use under the Valspar Zenith, get with your Valspar tech rep to go over materials and process.



From contributor O:
I agree with contributor about easing in. Another approach is to keep using solvents while researching and testing the waterbornes until you're satisfied that you can do an entire job with them. This way you don't need to work with a hybrid system. If dry times are your worry then try forced air and/or IR. You will be pleasantly surprised. We can get h20 primer ready to sand within ten minutes by using just fans in a 55 degree room.


From contributor A:
Orin is that the MLC primer?


From contributor O:
I don't want to push MLC because our results might well apply to all h20 primers but when writing the previous post I did have Aguqlente primer in mind. We're now going to start playing with light wet on wet plus forced air. By the way, our forced air is low-tech. Since I didn't know whether it would work well I bought 12 box fans from Lowes for $12/piece and we mounted them in a stand vertically stacked (3 fans) on a dolly.

My guess is that most, if not all water borne coating will respond to the forced air and not just the MLC. It may well be that others have enhanced drying characteristics. Even if this is true, we haven't found a competitor yet in terms of how easy AL is to sand.



From contributor A:
The first time I use the MLC Polystar Undercoater I thought I had found God. Contributor O, have you tried going over the Agualente primer with other products from other manufacturer's? In my experience leaving the spray fan going in the summer dries wb products very fast.


From contributor O:
I would recommend testing for any inter-mfg systems but I doubt there would be a problem if you're sanding the AL to 320 before applying the next coating. That said, the 320 sanding makes it feel like glass and I'm not sure if that helps site painting or hinders it. Of course they can always rub it down with Scotchbrite.

Also, I understand that the AL pre-cat primer is what goes under the Agua Barnice (post-cat) top coat. This is an attractive system but I have no idea whether AL primer / sealer would be ok under other post-cat topcoats like Duravar, Krystal, or Resistant. I rather doubt it but of course I have not heard of anything to contrary nor have I heard of anyone who would bother going this route. The point is, if AL primer can have post-cat Agua -Barnice on it then what else can it have on it? It probably depends on chemistry that I don't understand so if you do any research please let us know your findings.



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