Painting acrylic (plexiglas) sheet

[footrope]

Hi folks,

I am finishing up my first overhead hatch this weekend - replacement of the 1/2-inch thick acrylic. Learned alot, didn't swear too much, turned out pretty good (iidssm*). This weekend I'll take it to the boat for a test fit and see if I have to replace the gasket also.

I used Sikaflex 295-UV and their 226 cleaner and 209 primer. Their excellent directions recommend, for non-smoked acrylic (mine is clear), that a 1 inch border be added to the outer surface to block UV from getting to the bond surface.

Good idea I'm sure. I do not want to add a plastic or metal frame, so I've decided to paint the border. I was wondering if you had any experience painting acrylic sheet. I was thinking spray paint, something like a Krylon.

I think I'll take some pictures on the next hatch and perhaps post a project in the appropriate section. It wasn't hard, just labor intensive, and the cost is much less than the $500 each I was likely to pay if I hired an expert.

(* if I do say so myself)

 

[chaco]

I use 1-Part Polyurethane (Interlux Brightside) for Topside trim projects.
Adheres to fiberglass with an acetone cleaning and lasts many years.
This stuff is tough and not pleasant to work with (gums up FAST).
You need to have everything tapped off and work quickly before your brush
gets sticky. Highly recommend this paint for durability and longevity.
Krylon is enamel and won't last long. Maybe polyurethane is available
in a spray can ?

Happy Painting /) /)

 

[Guy Stevens]

Acetone not recommended for acrylic.

The Acetone actually attacks the surface of the acrylic, then permiates the attacked surface, significantly weakening it, it also permeates the structure of the acrylic and causes it to be more brittle, and more susceptable to cracking, crazing and more susceptable to UV degradation. At the edge, this is precisely where you don't want it to crack.

They make dedicated acrylic primers that do not have these negative characeristics which can be purchased from a good plastic supply house. Let me know if you can't find them, I will hit the shop this week, and pull a can or two and get the information off of it.

Guy

 

[footrope]

Primers

Interesting - the difference between acrylic and fiberglass resin/gelcoat. Acetone is great on gelcoat. I guess that's the value (lucky for me) of reading the Sikaflex directions and using their potions. The 226 Cleaner smells just like a strong alcohol mixture.

The Sika Primer-209N is a glossy black paint and I would consider using it on the outside except for the fast-drying problem. The first application flows on but within seconds the lighter elements are in your lungs and the next pass with the brush just makes it ugly. It doesn't level itself at all after the first pass. The 209 reacts with the acrylic, providing an ideal bond with the 295-UV, which acts as the adhesive and sealer in one tube. As a result of the reaction, it is hard to clean off any primer that gets past your masking tape after it dries unless you sand or scrape. One of my lessons learned. The primer contains "aliphatic polyisocyanates"

I talked to one boatyard pro about an estimate to do this work and he got pretty worked up about a re-glazing job he was currently doing for a picky owner (imagine that, a picky boat owner) and really acted like he didn't want the work. The guy that installed my heater also used to do these all the time, using the Sika products, and when I described to him what I did, he gave me a thumbs-up. Both guys said it would be an expensive bill from their companies, mainly due to labor and the fear that a leak would bring it back for a re-do for free. The acrylic and the three Sika products aren't that expensive. It took less than one $14 tube of the 295 to do the 21 x 21 hatch. There's plenty of the primer and cleaner left, although the primer is officially expired, but never opened before last week.

I could get way off the painting topic here, so I think I'll quit. If anyone is really interested, message or e-mail me and I can provide the document from Sika with the instructions. I think I will post a project, with pictures, when I do the second hatch later this year.

I will ask around and monitor the wisdom coming in here. Thanks, guys.

 

[Geoff Johnson]

What about a strip of non-skid tape around the edges? I often see it used on hatches. My boat came with a replaced lens in the main salon hatch and it leaked. I considered sending them to Select Plastics which seems to be the place of choice for Lewmar repairs but ended up buying new hatches and had covers made by JSI to prevent sun damage.

 

[footrope]

Anti-Skid on acrylic

That's a good suggestion, Geoff. I've been thinking paint, but anti-skid would be functional and reasonably renewable. The question comes back to sticking the stuff down. Use the regular adhesive or augment it?

The test fit of the hatch was successful yesterday - the gasket is OK. I washed the decks afterwards and no problem. Once I got it on there I decided not to take it off. It looks so good. While I was gone, Ellen made a cover out of navy blue sunbrella for it and we're leaving soon to test fit that and adjust the elastic. That will be our UV protection for now. We have such limited sunlight much of the year, I have to question whether I even need the trim strip at all.

Cheers,

 

[Loren Beach]

Blocking the UV

Hi Craig,
I keep my boat just a ways south of your venue (45 degrees lat), and can testify that the UV can really harm plastics. We have covers over the housetop hatches when we are off the boat, and they look like new after a decade. The Lexan fixed ports, OTOH, are quite cloudy after the same amount of time without protection. Admittedly the Lexan is much prone to UV damage than the acrylic used in the hatches, but still...

Note that UV penetrates clouds, and that's why so many NW residents get bad sun burns on cloudy days.

Loren in Portland, OR

 

[footrope]

UV blocking

Thanks Loren. We agree on the UV. We tend to use sunblock on our noses even with it is cloudy - unless it's raining. I will treat the edge or the entire upper surface in some way. We like the light in the boat, and will probably have to add shades underneath the hatches before summer, for use when we are aboard on a hot day. There are clear spray-on UV filtering coatings that probably would work also, come to think of it.

The test fit of the Sunbrella cover went well but we are still working on a way to keep the cover on the hatch. We thought we had a cinching method with elastic, but the grip isn't good enough.

Our 6 openable ports are very cloudy, but they haven't gotten yellow as I would expect Lexan to do. This winter's steady rain revealed the leaks around the port frames, so they are on the list to re-bed when the weather gets a bit more reliable. I am still trying to decide whether to try polishing them or replacing the acrylic or Lexan.

 

[Geoff Johnson]

I spray 303 Protectant on my hatches to cut down on the UV damage.

 

[footrope]

303 Aerospace Protectant?

Geoff,

I was doing some research on the 303 protectant you mentioned. The testimonials on the 303 Products website make it sound like pretty fabulous stuff - including a substitute for wax on boat topsides. I might have to give it a try on more than the hatches.

Thanks,

 

[stbdtack]

Craig , I spray 303 on everything, including the hatches. Works great to keep the colored lines from fading.

Been thinking of trying it on my scalp since the ever thinning hair isnt doing much anymore....