Practical Sailor Review

A Reprint from PRACTICAL SAILOR July 1998:
Poli-Glow Still Shine

After one year of exposure, several of our do-it-yourself restorers, as well as professionally applied Microshield, retain their protective glow.

Last spring, we took nine badly weathered, dull, and splotchy fibreglass panels and brought back their gloss and appearance (to varying degrees) with a collection of products known as "hull restorers." We then hung them on south-facing racks to face the Connecticut weather. We reported on them in the October 1, 1997 issue. Now, after a year of exposure, we took them down so that we could a) examine them, b) apply a fresh coat, and c) determine if there are any problems in removing them from the fibreglass surface.

As we said in the last report, these products are best thought of as temporary fixes; all of them can markedly improve the appearance of a weathered fibreglass surface, but none of them will stand up as well as a good paint job. On the other hand, most are a lot less expensive than a paint job, and last considerably longer than wax.

How They Work

When a boat is new, it's shiny with a uniform colour. That's because the gelcoat, which gets its colour. from very fine particles of opaque pigment suspended in the plastic film, has a very smooth surface. It's glossy because rays of light that strike the surface at an angle are virtually all reflected back at the same angle. As the fibreglass ages, sun and weather cause the pigments to change colour. from oxidation and UV exposure, and the gelcoat surface becomes microscopically pitted, so that light, instead of being reflected in one direction, becomes scattered, reflecting back in random directions. The change in pigment colour. results in a faded or blotchy appearance.

What can you do about this? Remove the surface layer with an abrasive. Sandpaper is generally too coarse, so a polish (very fine) or a coarser rubbing compound is used, followed by polishing. But it's just about impossible to polish the surface to a high gloss. Instead, a transparent film is applied.

Almost any liquid, including water, will provide a high gloss-for a while. The classic approach is wax. Our experience with waxes is that the best of them will keep a shine for six months or less, with three months being more typical. The most durable waxes we've found are the paste waxes, which contain more high-molecular-weight wax than liquid waxes; they're also more labour intensive.

Fibreglass restorers use even higher molecular weight to form a more durable film. Typically they use acrylic or acrylic-urethane resin. Just about all of the fibreglass restorers we tested consist of water-based emulsions of resin droplets, which form a clear film when the restorer is applied and the water evaporates. These emulsions have very low viscosities-much like water or liquid floor wax-and dry rapidly. This combination of characteristics makes multiple coats necessary, but means that application is easy and you don't have to wait for more than a few minutes before applying the next coat. Instructions usually call for about five coats,with three maintenance coats at the end of each year.

The Test

We found seven products, plus one for professional application, for a total of eight. Most are sold in kits (cleaners, strippers, polishes, final coat plus applicators).

Our test panels were taken from a severely storm-damaged 32-foot sailboat. All of them had a mottled surface with no trace of gloss.

We applied each product to a different panel, following the instructions provided with each system. For the dealer-applied Microshield, we sent a panel to the manufacturer, and asked him to mask off half and apply his product to the other half.

We checked each panel to see if water would bead on its surface, a good indication of protection. We also measured the gloss of each panel, then placed the panels outdoors, examining them after one, two, three, six, nine, and 12 months' exposure.

After a year, we brought the panels down. We divided each (except for the Microshield-treated one) in half, washed each down with a soft brush and a solution of liquid dishwashing detergent to remove surface soil, and again measured gloss and tested for beading. We then applied a maintenance re-coating (three coats, actually) to half of each panel. There have been in the past some concerns about the difficulty of removing these coatings, so we stripped the other half to bare fibreglass, using the stripper provided with each product, or, if there was no stripper provided, with the stripper from another product.

We stripped each half-panel down to a flat finish, and then applied five new coats of restorer, in order to see how a stripped and recoated surface would perform when compared to one that had been maintenance coated without being stripped.

What We Found

After a year, gloss had declined on all the test panels, but all still produced beading and most looked much better than the untreated panels had looked.


Although the gloss reading dropped from an initial value of 24 (spectacular) to 15 (merely very glossy), the panel coated with Microshield looks very good. After a year's exposure, it's as glossy as any of the other products we tested was initially. We're not trying stripping or applying maintenance coats; the manufacturer claims 8 years of gloss retention, and, in any case, we don't have the means of reapplication (Microshield is sold on a professionally applied-only basis, at $90-$100 per linear foot). We cleaned the surface with a detergent and a soft brush, and put it back on the roof.

Sea Breeze

The initial gloss reading of 2 dropped to zero after a year's exposure, although a water-beading test indicated that there was still something there. We found it easy enough to strip; although Sea Breeze doesn't provide a stripper.

We applied a maintenance coat of one application of Sea Breeze Polish and Sealant followed by one coat of Sea Breeze Boat protectant to the unstripped portion of the panel; we used two coats of each product on the stripped portion. Gloss readings of both halves were 2-the same reading we had obtained with our original application last year.


Vertglas, while it didn't have an exceptionally high gloss (6) in its original application, retained enough of it after a year to give us a reading of 1. This may sound unimpressive, but there's a huge difference in appearance between the dead-flat look of a panel scoring zero, and one that shows any gloss at all. Vertglas stripped easily using Vertglas Sealer Remover.

After we published the results of our first tests, The manufacturer commented that the product's initial gloss may have been adversely affected by our method of application; we had some problems controlling how much liquid was put down with the brush! sponge applicator supplied, so we used the alternative of a soft lint-free cloth. We practiced a bit with the applicator and then applied six new coats of Vertglas to the stripped portion of the panel and three maintenance coats to the unstripped portion. This time, our initial gloss reading was a respectable 9.

New Glass

With an initial gloss reading of 12, New Glass retained enough gloss after a year to register a 2 on our yardstick gloss meter. Despite some comments we've received about difficulty in stripping old coats of New Glass, we encountered no trouble using New Glass Stripper/Prep and a scrub pad. As a matter of fact, we also tried stripping it from a small boat that had been restored five years ago, and had been given yearly maintenance coats (three coats) every year since. It, too, stripped easily down to bare glass.

The recoated portion of the panel produced a gloss of 10-a bit lower than the initial reading we obtained last year, but probably within the margin of error of our test procedure.

Sea Glass

Sea Glass is a multi-step system, requiring (in addition to the cleaner) several coats followed by a topcoat of Sea Shell Protector. Its initial gloss of 8 wasn't bad, but after a year outdoors gloss dropped to zero (although water beading still occurred).

The Sea Glass kit comes with a handy scrubber and this, in conjunction with Sea Glass Fibreglass AU Remover, made stripping easy. Sea Shell Protector, as far as we can tell, is a wax. We found that enough of it remained so that we couldn't apply a maintenance coat of Sea Shell Protector without stripping the old surface. We applied two maintenance coats of the Protector to the unstripped portion of the panel, and applied our original schedule of five coats of Sea Glass followed by two coats of Sea Shell Protector to the stripped portion. The gloss of the maintained section was only 2 (the gloss of the original application was 5).


TSRW (an acronym for This Stuff Really Works) behaved, in many ways, like Vertglas. Although its initial gloss reading last year was only 3, it held up well, giving us a reading of I after a year. We weren't impressed with TSRW's Stripper, though. Label instructions call for applying it diluted with water, but we found that it didn't do a complete job that way; we tried it again full-strength. Even then it failed to completely remove the old coating. We found ourselves with a streaky surface. Finally, we tried New Glass Stripper, which did the trick.

When we re-applied TSRW (six coats over the stripped portion, three maintenance coats) we once again got an initial gloss reading of 3, the same as we obtained by just applying three maintenance coats to the unstripped portion of the panel.


Higley's initial gloss of 5 dulled down to zero after a year's exposure, although it continued to cause water to bead. It stripped easily with Higley FiberPrep Gleaner. After three maintenance coats applied to the unstripped portion, gloss came back to 4, or virtually the same as the original. The stripped and recoated section produced a gloss reading of 5.


Poli-Glow, with an original gloss of 15, provided the best gloss of the do-it-yourself products. After a year, the gloss dropped to 2, the same as New Glass. This still represents a considerable improvement in appearance over a product that scored zero. Poli-Glow's stripper removed the year-old coating easily. The panel section that had not been stripped was given three maintenance coats of Poli-Glow, and achieved a creditable gloss of 11; the stripped and re-coated section produced a gloss of 13.


The most permanent fix for a loss of gloss is a good paint job, preferably with a two-part polyurethane.

A bit lower in cost, and possibly in durability, is dealer-applied Microshield. If it lasts for its claimed eight years (all we know is that it looks good after one year) its $90-$100 per linear foot becomes attractive, compared to Awlgrip's $100-$200 per foot (when applied professionally).

Considerably lower in cost are the DIY restorers. These cost $35 to $60 for a kit ($15 to $40 for the restorer alone) that will cover a 25' boat. The best of these will provide a reasonable gloss for at least a season; a maintenance application of another three coats at the end of the year will bring back the gloss. All are quick and easy to use, and dry in minutes.

We've heard reports of some of these products going milky, flaking, or cracking; we've never experienced any of this in our five years of testing this type of product. We've also heard reports of difficulty in removing these restorers; again, we've encountered no problems.

Fibreglass restorers aren't a good idea for new boats. Best to apply wax for surface protection.

For boats that have become dull and streaky, though, fibreglass restorers provide a moderate cost, moderately durable fix. Based on our tests, we prefer Poli-Glow, New Glass, TSRW, and Vertglas. And, while Microshield looks great, we'll have to wait a while longer to see if it's worth its stiffer price.

Product Size Price/Kit Price/Restorer Ease of Application Ease of Stripping Initial Gloss Rating Gloss after 12 months
Microshield n/a n/a* --- n/a n/a 24 15
Sea Breeze 16.9 oz. $35.60 15.10 Fair Excellent 2 0
Vertglas 16 oz. $69.95 $26.95 VeryGood Excellent 6 1
New Glass 32 oz. n/a $40 VeryGood Excellent 12 2
Sea Glass 35.2 oz. $107.60 $39.95 Good Excellent 1 0
TSRW 32 oz. $52.90 $39.95 VeryGood Fair 3 1
Higley 32 oz. $45.00 $35.00 VeryGood VeryGood 5 0
Poli Glow 32 oz. $49.95 $37.95 VeryGood Excellent 15 2