Question about paint chemistry

[Joe Frickin' Friday]

Finally...if my boss asks why I'm posting to BMWST during the workday, I can tell him it's work-related.  

 

We have some PPG PITTTHANE paint and catalyst:

 

 

 

We need reducer for it.  The contractor who handed over the paint said they used ProKote 870 urethane reducer (medium).   Turns out 870 urethane medium reducer is available under a bunch of brands, but all we've got on hand is this stuff:

 

 

It's sold as part of Sherwin-Williams' Polane polyurethane paint system.  I don't know much about paint chemistry.  Can someone tell me whether this Polane reducer is likely to work with PPG's paint?  Or do I need to go shopping and get some genuine 870 urethane reducer?

[MT Wallet]

If this is a serious question call the PPG store at 734-665-6241 and ask.

[realshelby]

I paint cars. Just finished spraying my 1965 Mustang. Sealer, base coat, clear coat cost just under $3000 at "shop discount". I have learned the HARD way that using components NOT matched can have serious side effects. 

 

I very much like to stay with one manufacturer, and even that manufacturers "line" of products. 

 

BUT......there is one place that I would consider cross branding and that is reducer. Seems it is pretty much very near the same. That decision would be based entirely on what I am painting. If going for a show car finish, no. The work involved in that is too much to chance anything going wrong. But painting lockers, parts, etc. I would have no issue using the reducer you have. I MIGHT test a small area and see how it lays and if it solvent pops ( lots of little pockmarks in the paint) or crazes or anything. 

 

Of course there is a way to do it right, and buying the proper recommended reducer is that. 

 

Temperature has to be considered. Medium reducer ( the catalyst may have a temperature range too) is common. If you are seeing too much orange peel, if finish seems to be going on too dry with little gloss, then go to slower reducers and catalyst's. I use the slowest drying components for my work, but dry times are not a factor for me. 

[Rougarou]

[Joe Frickin' Friday]

On 12/20/2023 at 1:15 PM, MT Wallet said:

If this is a serious question call the PPG store at 734-665-6241 and ask.

 

Thanks for the tip.  They weren't able to answer my question directly, but they referred me to another PPG contact who said it should probably work.  It's such a hassle to buy stuff these days that I would much rather not buy something unless I really have to.  

 

On 12/21/2023 at 9:06 AM, realshelby said:

BUT......there is one place that I would consider cross branding and that is reducer. Seems it is pretty much very near the same. That decision would be based entirely on what I am painting. If going for a show car finish, no. The work involved in that is too much to chance anything going wrong. But painting lockers, parts, etc. I would have no issue using the reducer you have. I MIGHT test a small area and see how it lays and if it solvent pops ( lots of little pockmarks in the paint) or crazes or anything. 

 

This is for a bare-aluminum cover on the cooling module for a heavy-duty engine dynamometer, so not looking for a "concours d'élégance" finish.  I'll have our machinist try a test piece, and if it's durable and not too orange-peely or pocked, we'll go ahead with the whole piece.

[roadscholar]

4 hours ago, Joe Frickin' Friday said:

This is for a bare-aluminum cover on the cooling module for a heavy-duty engine dynamometer

 

didn't see it mentioned but for painting bare aluminum you should probably use a zinc-chromate primer or something similar to make the paint stick to aluminum.

[realshelby]

23 hours ago, Joe Frickin' Friday said:

 

This is for a bare-aluminum cover on the cooling module for a heavy-duty engine dynamometer, so not looking for a "concours d'élégance" finish.  I'll have our machinist try a test piece, and if it's durable and not too orange-peely or pocked, we'll go ahead with the whole piece.

In that case, and especially if "color" isn't important, I would simply use a quality Epoxy primer. No reason to top coat epoxy as it seals as well as paint. Regardless, PROPER application of Pitthane over bare metal requires a primer coat first. 

[Joe Frickin' Friday]

1 minute ago, realshelby said:

In that case, and especially if "color" isn't important, I would simply use a quality Epoxy primer. No reason to top coat epoxy as it seals as well as paint. Regardless, PROPER application of Pitthane over bare metal requires a primer coat first. 

 

I'll have to double-check with the powers-that-be, but I had the impression that color mattered for this application, as the cooler cover would then match the new dyno right next to it.  

 

Thanks for all the advice.