Thinning

I'm new to SW hotline, and I sprayed a test line using a 319 tip (recommended by rep). I did not thin the paint at all because 99% of the time I don't have an issue. The line was narrow with some serious build up on the edges and super thin down the middle. If need be, how much water should I use to thin just 5 gals of hotline? I love the color and want this paint to work. Thanks

Thin as needed to get the spray pattern you want. You can also try a bigger tip.

the amount of thinner will greatly depend on the temp you are working in. id start with no more than 3 or 4 onces. stir it in very well and do a test. keeping the paint stored in a heated area will help also.

You will only be "experimenting" as to the amount the first time. Occaisionally you get a new batch that sprays differently, but the bottom line is that you need to continue working. My suggestion is to only add enough to take the "edge" off the paint. The first time you may add too much or not enough. At that point you will have your baseline for future reference. With waterbornes I add about a cup (8 ounces) and I do not measure, just pour. It seems to solve issues every Time! Could I add 2-4 ounces? Probably, but a cup resolves issues instantly and the demo (in your case the job) goes on. After you add, box the paint by pouring the bucket into an empty bucket back and forth 3-4 times. This mixes it well enough to work. With solvent based, I go with about the same amount or less (per Straightline's recommendation) and refine from there with the next bucket. Simple fix.

If you do over thin don't throw out the paint, you can use it to thin down the next bucket of the same color.

in my experience with new asphalt or coal tar sealer over thinning will make the paint turn brown or brownish.

So I have the thinning a try. I'm beginning to think its a tip issue. I tried a 319, 321, 419, 421, and 423 yellow handled tips. All sprayed hard down the sides. I used my old 421 black handled tip and it sprayed great. Perfect coverage on the new asphalt. Contractor tips might be my answer

I just want to know exactly how to spray this paint. Many specs require this paint specifically!

As for "exactly how to spray this paint", we all have to find what works for us - today. There many other variables that may be unique to your set up or circumstances. Unfortunately, tomorrow the humidity or barometric pressure or the alignment of the moon and stars may be different and things will work a little bit differently. All in all, You appear to be on the right track. Over the last couple of years, I have been using the black tips more frequently and with great results; especially with SW Hotline. As you observed, more uniform coverage over the width of the stripe but still with clean crisp edges; especially on rough seal coated surfaces (fewer tails on the edges). I have been wondering if there has been a change in the manufacturing process for the black tips because they seem to paint a better line than they did a few years ago. Has anyone else noticed this? Several years ago, we almost always used a 4XX yellow tip for waterborne paints to get a consistent 4" line with good coverage. We would have to set a 3XX tip about a foot or more above the pavement to get a 4" line; which caused problems on windy days. But, the 4XX tips only had to be about 3 inches above the pavement for a good 4" line. At that time, SW waterborne paint seemed to be noticeably bulkier viscosity than the SW solvent based paints. We used 3XX tips for the solvent paints it get 4" lines.