Comparing Interlux Brightsides (IB) to the new Rustoleum Marine Paint (RMP)
FYI: I used IB on the hulls and decks of my trimaran sailing dinghy. Then, I used the new Rustoleum marine paint on my rudder assembly parts (tiller, headstock, blade) and inside the footwell. I would have used IB in the footwell but I ran out of IB and didn't want to buy another whole quart just to do a little footwell. So, RMP in the footwell it was.
Important: Because I used these paints on a trimaran dinghy that will not live in the water, I didn't use a bottom paint. For a boat that lives in the water, a good bottom paint will need to be used below the waterline.
Here's my thoughts comparing the two paint systems:
Primers: Both systems use high build primers. The IB primer builds more and sands to a much smoother surface. I was actually amazed at how smooth the surface sanded back. And you can visually see your sanding progress. Unsanded, the grey primer I used had a light gloss. Sanding back, the grey took on a lighter grey, matte finish. It was easy to see areas that needed more sanding . . . or more filler. The Rustoleum primer was also very good, but not quite as amazing. I would have used grey for the RMP primer, but the store only had white. I like grey primer, because it's easier for me to see surface problems and sanding progress. It's also more clear when your top coat system has built up enough hiding power. If you can hide the grey, you know you've got enough paint on at a minimum. Some people have said you can skip the primer and still get the topcoat to adhere just fine. Maybe that's true. But I think using the high build primer is a key step to getting a smooth painted surface. Big difference if the primer is not used. I tried not using primer on my second outrigger, because the IB top coat provided such a great finish on the first outrigger. But on the second outrigger, the texture of the plywood hull up by the gunwhales where I didn't fiberglass and didn't prime telegraphed right through. So, I sanded back and re-painted with the primer. With primer and top coat, the plywood texture was invisible. Indeed, the hull side looks like it comes off a mold. I saw similar texture hiding capabilities with the RMP primer, but not to the same degree. The IB system looks sprayed/smooth from inches away. The RMP system looks smooth from 2-4 feet away. Of course, good surface prep, including removal of particles with a tack cloth or the like after sanding, is a key to getting very good results with either system.
Self leveling top coats: The IB top coat self levels to a point where brush strokes are not visible at all. With good surface prep including primer, the surface looks like it came out of a mold. For RMP, the top coat self levels very nicely but not to the same degree as IB. Up close, you can still see brush marks (or foam marks) in an RMP top coat. From 2-4 feet away (more often closer to 4 feet) these are not visible to my less-than-eagle eyes.
Coverage: The RMP top coat covers better. Two coats over the primer gives solid coverage. IB top coat takes 3 coats. Sometimes 4 coats. Both primers gave excellent coverage in a single coat. Because the primer gets sanded back, I was only somewhat careful to roll/brush on primer (or roll and tip) smoothly, mainly to avoid runs. I also made sure I tipped out any thing rolled on. No need to be a fanatic with the primer. Reasonably smooth is okay. Hence, priming went fast (20 minutes per hull below the gunwhales . . . actually above the gunwhales since each hull was upside down). I was a lot more careful when applying the top coat. Hence, top coating took more time (hour per hull, below the gunwhales).
Gloss: Both are quite glossy, much glossier than a gloss exterior paint such as a deck enamel. But, IB has a lot more gloss. I'd say RMP clearly has a wow factor. But, the top coat of IB is spectacular. Standing in front of my main hull covered with IB, I can read the letters and see the colors and graphics in my reflected T-shirt. For RMP, I can see a shadow reflection with the general shape of my head and shirt, but no detail. Stand in front of your typical glossy house paint and you probably won't see any reflection period.
Durability: I can't comment yet. IB seems harder but I need to let the RMP dry a few more weeks to see how it hardens up. My IB paint on the hulls has been cured for a handful of weeks now.
Primer Cost: Roughly $22 for RMP primer compared to about $38 for the IB primer (prices per quart). There are cheaper prices online, but pay shipping and handling and you end up almost in the same place. Both primers are expensive, but RMP primer costs a lot less.
Topcoat cost: Roughly $12 for RMP compared to about $38 for IB (prices per quart). Compared to IB, the RMP topcoat is a huge bargain. Online prices for the IB top coat suffer the same foibles as the online primer prices (The RMP top coat is so inexpensive at local building supply stores like Lowes or Fleet Farm, why bother with online issues for RMP?). For example, one online distributor sells IB top coat for $27 per quart. Seems like a great price compared to $38. But, shipping is $5 per quart, and then there's a hazardous material handling charge. Ba da bing, you're up to $37. So, I just paid $38 from my nearby West Marine store and didn't have to wait a week for shipping.
Touch up: Both touch up easily. I was concerned with this for both paint systems. I got an early chance to investigate, unfortunately. Stupid is as stupid does, I banged an 8 foot metal angle iron into the side of one of my outriggers (painted with IB and primer system) near the bow, pivoted to see what I did and banged the iron near the stern. Two dings. Ouch. I sanded the banged areas with 220 grit, brushed on a top coat (no primer) and tipped out with a foam brush while blending a little into adjacent areas. After two coats of this, the touch ups dried as smooth as the rest of the hull and could not be discerned even at an oblique angle. To test the RMP, I lightly sanded out a couple of spots on my rudder blade (coated with RMP) and touched up with top coat. Took only one coat, not two, to fix the RMP so long as I didn't sand through the primer. Two coats if I did. The new areas blended very well, but could be discerned at an oblique angle. Only a fish would have that angle in use, so I'm not too concerned.
Colors: RMP currently has a limited standard palette, while IB has many more standard colors available. If Rustoleum gains momentum in the market, maybe the company will offer more standard colors. That would be a huge plus, making the system much more appealing in more circumstances.
Mixing: Mixing before use is important! Both primers come with solids well separated from the liquid. This doesn't mean the primer has to go back, though. I think this can be expected for high build primers. In fact, when I saw this was an issue when I first opened the RMP primer can, I knew it would have good build properties. In any case, thorough mixing fixes this phase separation. Initially, it took about 5-8 minutes of steady mixing for both primer brands to become smooth, creamy dispersions. Patience is needed to mix well, but the mixed primers perform well. If the primers don't become smooth and creamy with this mixing, then the paint might be old and I'd suggest taking yours back. After the initial mixing, the primers stayed pretty well dispersed during my painting phase. Phase separation in the can is not an issue for the top coat paints. The top coats of both brands mixed quickly and easily.
Drying: I had no issues at all with either system. Both dried on schedule. In my case, I mixed the paints and primers well. I also used MAS epoxies and had no amine blush issues (in case blush or mixing might be drying culprits). My surfaces being painted were very clean. Some folks online say the IB primer didn't dry for them. Maybe they didn't mix or maybe they tried to coat over amine blush.
Ease of use: I have to admit, I was a bit nervous using the IB system for the first time. I had never used an expensive marine paint system like this before. I worried that some kind of magic might be needed to access the advertised results. But, there's no need for nerves or worry. I found the IB system as easy to use as any paint system, and the results are pretty spectacular. Apply with a foam roller and tip out with a foam brush and the paint works great. It's jaw dropping, really as to how the top coat self levels a few minutes after application. Having such a good experience with IB, I used the RMP without hesitation or nerves. Same ease of use. Note: the cost of consumables, such as rollers and brushes, can really add up. By storing my rollers and brushes in clean ziploc bags, I was able to re- use the consumables even after leaving up to 24 hours between coats. I never had to clean a roller or foam brush and just threw them out when done with the whole job.
Conclusions: Clearly, if cost is an issue, RMP wins hands down. But for a spectacular finish, IB wins hands down. So, I would recommend using both if the budget allows. Where a spectacular finish matters (such as hulls, decks, and a highly visible cockpit), I'd use IB. On the rudder blade and daggerboard/centerboard, I might also use IB because it has Teflon ingredients that theoretically might provide a smoother, more slippery surface. For other areas, I would use RMP (interiors, lockers, etc.) based on its cost and quite good finish. After I get some experience with the durability of both paint systems, I might revise these conclusions. If I had a bigger more significant boat, I'd be tempted to try the Interlux Perfection system, which is a two part paint that is said to have a lot more durability than IB. I have no current experience with the Perfection system to offer any comment. Qualification: If I were not taking the time to do very good surface prep, then I would not use IB. I think thorough surface prep is key to getting the spectacular coating results. In such a circumstance, RMP or another less expensive paint alternative would do just fine.