The Rot Doctor


Subject: Nonskid Deck Coating
Date: Wed, 03 Jul 2002

Hello Doctor:

Your advice and products really helped out on the last project...I'm now considering another (we boat owners just hate to sit still!).

Glad we could help!

The boat is a late 70's 33' sport fisher. The deck is fiberglass with gel coat, but has been coated in the past; by us and by previous owners. Two years ago we redid the nonskid colored portion using Interlux Brightside Polyurethane (Grand Banks Beige color). We also added Interlux Nonskid Compound (polymeric spheres) to enhance the nonskid characteristics. The job we did looked and worked great but there are hairline cracks that are coming back and the paint is coming off in small areas--time to redo.

We are considering your Uniflex 255* and using your "option 2" application (CPES then 2 coats of Uniflex 255*) and have the following questions:

1) Can we use these materials without sanding and stripping off the old materials?

The CPES will certainly adhere to any clean (no dirt or oils) surface that is not a polyethylene plastic. However, if the old Interlux is starting to come off, the CPES/Uniflex* will not keep the Interlux from coming off. The CPES/Uniflex* will stick great to the Interlux, but if the Interlux comes up, so will the CPES/Uniflex*. Sanding any surface is not absolutely necessary, provided it is not oily or dirty. Sanding assures that there is no surface contamination, and additionally provides a certain amount of mechanical adhesion, thereby giving a stronger bond, so sanding is almost always preferable.

2) What preparation should be done prior to the CPES? We figured we'd do a real good cleaning and scrubbing; any other suggestions?

See above answer.

3) Can the CPES primer coat be applied with roller? If so, what type of roller?

A lambs wool roller works fine.

4) How long do we let the CPES cure before application of the Uniflex*?

Until the CPES is no longer sticky to the touch, usually 6-24 hours depending on conditions.

5) Can we use the Interlux Nonskid Compound polymeric spheres in the Uniflex*?

Yes. Some Nonskid additives tend to settle, so stir occasionally.

6) We are hoping that we can coat over the hairline cracks without filling them, do you think the CPES followed by Uniflex 255* will cover and hide the cracks? (When we did the job last time the cracks almost disappeared, but over time have come back).

What happened is that the cracks filled with Interlux, which skinned over at first, but then shrank over time. If you decide to sand the Interlux off, there shouldn't be problem. If you decide to coat over the Interlux, you will need to fill in at least the areas where the Interlux is coming up in order to have a nice smooth finish. I would treat the hairline cracks as just another area to prep, and make sure the cracks are filled with something that is not going to shrink like the Interlux did. Surface prep is at least half the battle to a job well done.

7) Lastly, can you mail color chips for the Uniflex 255* in Burlap, Sandstone and Brownstone??

We don't have any color chips of the actual product itself, but we will send a color chart.

Any other suggestions you may have for this project will be appreciated. Thanks in advance for your help.

I would either:

1. Sand down to the gelcoat. Apply CPES/Uniflex*.

2. Chip up any loose Interlux. Clean, then prime the chipped-up areas and the hairline cracks with CPES. Fill in the chipped-up areas and any hairline cracks that didn't get completely filled by the CPES with a non-shrinking filler such as our Fill-It Epoxy Filler. Sand the Interlux and Fill-It to get a smooth surface over the whole area. Apply CPES/Uniflex*.

Sincerely, Gary


* Since Uniflex 255 Aliphatic is no longer available, we suggest our Elasta-Tuff™ 6000-AL-HS instead.