Prepping hypalon for number paint

[Northern Pike]

I will be painting registration numbers on my new hypalon RIB.
What is the best way to clean, prime, and prepare the surface for the best adhesion?

[jwalker]

Use detergent to thoroughly clean the area, rinse it, dry it then wipe with cellulose thinners or acetone just prior to painting to open up the structure so that the paint gets in rather than just on.

[Northern Pike]

Thanks JW. Acetone won't harm or weaken the hypalon?
Is MEK any better or worse?
I have some Polymarine lettering paint but I don't have their primer. According to their website it "contains" MEK. I don't know if that means it IS 100% MEK, or if it has other components as well.

[jwalker]

Acetone is widely used on hypalon during the glueing process. The disadvantage is its quick evaporation, standard cellulose thinners I use because it's much slower. MEK is normally used for pvc, it too has very fast evaporation. Check your paint is not designed for pvc, if it is it will work but it'll be prone to cracking as time passes. Plain hypalon paint is very durable and remains flexible for a considerable time. My hypalon paint boat name was applied in 2004 and is still fine. However, if you clean your boat in the future using a solvent you need not to linger on the painted parts! Rather than painting, you can glue on hypalon letters and then they'll last as long as the tubes and can safely be cleaned.

[Northern Pike]

Thanks again, JW!
The paint is clearly labeled "for hypalon."
I have used both acetone and MEK many times in the past; the latter on my previous PVC Zodiac. I used vinyl paint and a stencil to number my PVC boat, with MEK prep, and it lasted perfectly for decades.
I like that look so I'm going to do the same with my new boat.
I know MEK is best for PVC, which is why I found it odd that it was listed as a component of the primer for hypalon. Hence my questions.
I'm concerned about the primer either dissolving the vinyl stick-on stencil, or seeping under it and dissolving the glue and leaving a void that the paint will seep into, messing up the outlines of the numbers. I guess I'll just have to be careful, and do a test on the stencil before I start.
I haven't used this paint before.
The spray on vinyl paint, sold for car seat touch up, works great on PVC!
Cheers!

[Northern Pike]

BTW, I don't know what cellulose thinners is. I'm sure we have a different name for that on this side of the pond.

[Ferryman]

It’s car paint thinner, it evaporates very fast - I’ve got no idea what it’s called in Canadaland!

[Northern Pike]

Lacquer thinner, maybe?
I have a friend with a body shop. That should be easy to get.