Airless spray bottom paint

[Strecker25]

So I have a new fun tool, a nice Graco airless paint sprayer. I bought it to paint our finished basement that’s in progress and today while doing the ceiling it dawned on me how quick I could coat the bottom

I’ve used petit hydrocoat eco for years with great results, and the petit documentation states sprayer is an acceptable method of application when thinned with water.

Being due for a coat in the spring I’m excited to put it to use but my question, anyone tried spraying vs rolling?

Of course, prep is important and I’ll have to mask off the hullsides to avoid overspray along with protecting any nearby boats. Try to catch a calm day too

 

[Stee6043]

I feel like you'd spend more time masking and covering the floor than you would just rolling it the old fashioned way? I sprayed the ceiling and walls in my basement with a Graco. It's a great time saver if you don't have to cover anything up!

 

[Mauler34Rod]

I would be concerned with how much you have to thin to apply with sprayer. I feel like the thicker the better for longevity.

 

[Yendor]

I surely would not be the guy to discourage a man from making good use of a new toy, but there may be a couple caveats that could weigh in your decision that perhaps you've overlooked.

As was already mentioned, overall time frame and finished thickness are the two major variables that will change with method of application. After having sprayed more than my share of roof coatings I would likely go ahead and roll the boat bottom for the following reasons.

The end result you want to attain is going to be x# of dry mill thickness.
This # would be the manufacturers recommendation, depending on the material.

In the case where you're using an ablative type of paint, increased mill thickness will provide increased longevity. When you start thinning anything, you are effectively decreasing the percentage of solids, which means more passes to attain the same dry mill thickness. I will tell you from experience that attaining the same millage on a vertical surface (walls) vs one you standing on (roof) is not possible. When coating a ceiling (or boat bottom) that reality would be compounded again. In other words, I would expect it would take two passes (or maybe three) to equal the thickness that could be applied with a roller in one pass. While it's true that covering, masking and removing the same will only need to be done once, if it's going to take four (or more) passes to get your desired millage, the roller application starts to look much better.

The other reality about spraying and thinning is that the more it's thinned, the easier and more thoroughly it atomizes, the more easily over spray becomes uncontrollable (in addition to less dry fill thickness attained). When you say "try to catch a calm day" I doubt you realize the magnitude of this understatement. I had a contractor that did a garage roof at a dealership and 'over-sprayed' a few dozen new cars. He learned the hard way, we would NOT want you too, as well.

Now, if the case is you're using an epoxy type of hard non-ablative paint, excessive thickness will not further your cause so those issues may not apply, BUT . . . realize before the fact that cleaning even the coolest Graco rig can be and usually is, a giant PIA when you need pump and spray some kind of solvent through them to thoroughly clean the pump and hoses. This is a completely different ballgame than hooking up a hose and using water.

I could go on, but don't want to ramble (if it isn't to late).

As with anything, unknown specifics can lead to generalizations that may not be correct, but . . .
IMO, a good Graco rig may be among the tools 'most fun out of the box', but would also add that spraying a boat bottom isn't among the best test subjects to be had for such a purpose, and quite possibly not the correct tool for the job.

 

[Lazy Daze]

I like the thought of it... but personally, I wouldn't bother. I don't think you'd really save any time in the end - especially once you factor in clean up time.

BP is awfully thick... which Graco did you get? Depending on the model, it may not even work.

 

[Strecker25]

Thanks guys, good points. Rolling seems to take forever and painting evenly over the lifting strakes drives me nuts but the thickness mils is certainly a concern. I was surprised to read hydrocoat even supports spray application, which is what got me thinking.

I have the Graco x5 - quite capable but still planted in the middle of their DIY line.

I have a spare (and old at this point) can of hydrocoat. I’ll do a test spray at some point on a scrap piece of something and see how it comes out. Probably end up just rolling the bottom the tried and true way, though.

 

[Lazy Daze]

There's a number of different Graco's - I wasn't sure if you had the more "handheld" version, or not. That model might do it - testing it, as you said, is a good idea. As you know... be sure to mix up the AF really well - especially if it's been sitting as there could be large clumps on the bottom.

 

[ttmott]

$250 per gallon - every drop is going on the boat....