synthetic enamel paint

do you need to put hardener in synthetic enamel paint ? I have painted tractors with alkaline enamel 7 have had very little problems with it using hardener I like it. But I have tried to use synthetic enamel 3 times & have had problems every time. I used Valspar hardener all 3 times.I was thinning with naptha . Can anyone give me some help
Thanks
Richard

What you are calling alkaline enamel is alkyd enamel. Synthetic enamel is another name for alkyd enamel. They are the same. Perhaps you changed brands, follow the instructions on the can, or get another brand.

What problems did you have?

I think the naptha you used for thinning the enamel is your problem. Saving money on ingredients, is like starting out on a long trip with an almost empty gas tank. You won't get far, but yer car will be pointed in the right direction!

Save a little on materials, spend lots of time, doing it over, or getting an unsatisfactory job.
Next time--buy the correct thinner/reducer for the brand/type of paint you buy. After all-the people who make the paint spend lots of time designing the reducers/ thinners that will be compatible with their paints! Its like building a large building, but not having a foundation under itt, just setting it on a stack of red bricks, or river gravel---won't last long. Have you seen the pictures of the 12 story apartment building in China that fell over? After it was built on concrete pilings, then they started excavating the ground under it, and piling the dirt behind it! A heavy rain, and the force of hydraulics, pushed the building over on its side. Broke the concrete pilings, with no foundation, and over it went! I imagine heads rolled over that.
to wit: No paint job is any better than the foundation you put under it. Do it correcly from start to finish, and it will be good!