Join Date: Jan 2003
Location: Maine Coast
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More on LPU's
Both Imron and Awlgrip can be touched up and repaired by an experienced professional. The key word there is experienced!
There are, however, significant differences between these two linear polyurethane (LPU) paints. Both Imron and Awlgrip happen to be the best-known examples of the two main classes of LPU coatings but they are not he only ones. There are two basic types of LPU's acrylic polyurethanes (Imron, Awlcraft 2000, Interspray 800, PPG Concept, Sikkens Yachtcryl) and the polyester polyurethanes (Awlgrip, Interspray 900, Sterling, etc.) Both acrylic and polyester LPU coatings produce a beautiful wet-look shine that, with proper care, will last a full five or six years before any noticeable difference appears. The main difference is the polyester LPU yields a harder, more weather- and UV-resistant finish so your boat stays glossy longer, with less work, with Awlgrip than with Imron. This is the claim any way!
Hatteras Yachts used Imron for years and years with very good results, this is why I say, "this is the claim".. If I'm not mistaken they have now switched to using Alwcraft 2000 which is very similar to Imron just made by Akzo and not Dupont..
The problem with the polyester LPU's, like Awlgrip and Sterling, is that when they cure a thin hard surface is formed like a built in clear coat. This becomes a problem when and if you try to buff Awlgrip or a polyester LPU. Most people don't realize it but are actually only buffing this very thin surface layer made up of mostly the clear solids. Picture oil and water. As you shake the bottle they almost form together but if you let it sit the oil rises to the surface. This, in a sense, is what Alwgrip cures like with the clear solids rising to the surface to protect the pigment layer. It's really more complicated than that but it's about as easy as I can explain it. In most instances, when buffing Awlgrip, you will burn through this thin outer layer quite quickly using compounds & polishes. Once you've done that you'll be a slave to the Awlgrip until it's worn away or re-painted.
We've all seen Awlgrip that's been chaffed by a fender or a winter cover. This chafing has basically worn through the "clear solids" and has exposed the base layer of the paint leaving it unprotected from the sun.
Many smaller boat shops recommend and use the acrylic LPU's because they are a lot easier to work with. An acrylic LPU, like Imron or Alwcraft 2000, dries faster, and because itís a solid paint, itís easier to perform the buffing required to force a smooth shine onto a mediocre spray job full of dust and dull areas. We did an after the fact buff job on Tim's Imron (the red boat above) and I can tell you this paint is plenty hard! Finesse It II and Chroma 1500 barely touched it until after we had buffed it with Superduty Rubbing Compound and a foam "polishing grade pad".
Awlgrip is quite unforgiving and itís a lot harder to get good results in marginal painting conditions with but it purportedly lasts longer. Both types, acrylic and polyester LPU's, can be repaired by spraying a patch or brush touch-up and then wet sanding and buffing to blend it with the surrounding finish. Special blending additives help as well as experience.
One of the biggest problems in repair work is color matching and that's where Awlgrip shines. Alwgrip reportedly, I say reportedly because of the red boat above, has better fade resistance to the acrylic LPU's and an Awlgrip hull color stays stable and fade-free longer than an acrylic. How much longer I don't know but these are the claims.. The problem then becomes how good is your repair guy at feathering an Awlgrip job vs. the much easier feathering of a acrylic LPU like Imron. I'll take an acrylic LPU over a polyester LPU for just the ease of repair any day.
Tim's boat had some definite ghosting where the old name was but hell it's fire engine red, the color that fades easiest, and even Awlgrip would have ghosting at that age.
The take away here is to know that Awlgrip should not be buffed unless it's a last resort and Imron or Awlcraft 2000 can be polished but don't over do it because you only have 2.5 - 3 mils to play with...
-Maine Sail / CS-36T
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Last edited by Maine Sail; 01-15-2008 at 07:47 AM.