Gotchas and cautinary tales of adhesion issues.

Some of the things that cause adhesion issues, are small.

You can have adhesion problems, if you use epoxy to make repairs and don't fully remove the amine blush.  This stuff is water soluble, but waxy and water beads up on it.  Paint, primer, and other epoxy fairing compounds do not stick to it. 

If you take a spray bottle, and go around and mist the boat, you want the water to not bead up and hang on your repair areas.  You can use red scotchbrite and water, to scrub the repair areas.  If you use clean lint free white cotton rags, the amine blush comes off as an orange/brown color on the rag.  Scrub, and rub, until you have clean water on a clean rag.

Next you want to solvent wash the surface.  I like to use Interlux 202 as a cleaner, as it lasts a long time on a rag.  You want two rags, one dry and one wet, and fold them into squares so you can fold to show a clean face as either gets dirty.  You wet the surface with one, and dry the surface with the other.

The goal, is not to take a spot of contamination and spread it evenly over the whole boat, but instead of lift any oils, greases, or contaminates that the solvent can lift and put them on a dry lint free rag, and then turn the rag to a new clean face.

Cautionary tales, have to do with hydraulic fuel from yard equipment, and diesel soot from near by boats.

Most adhesion problems I've seen, involve surface contaminates that occur mid-job.  The closer to the high build stage you are, the more quickly you want to move through to finish primer, as the more talc in the material you are putting on the more absorbent it is.   Little round spots of oil, are something to pay attention for, as are soot splatters.

If you are near an airport and have exhaust dirt, or down wind of a burger joint that has a big exhaust hood you can have environmental related contamination based on the wind direction, so just keep in mind that not all oil arrives from shoes!