Crazed Acrylic

[emandvee44]

Our saloon hatch acylic is crazed. Close examination shows that the crazing only penetrates a few microns. Before I order a replacement, has anyone any experience of restoring a crazed panel, and if so how?

The stripe is where previous owner had put non slip strips - coded boat, nanny state?
Thanks,
M.

 

[Laminar Flow]

I'd love to hear that the crazing could be removed though I have been told it could promote the panel to fracture.

 

[Concerto]

You could try sanding mechanically an area with 180 grit wet (use a plant spray). Once the crazing is removed, then reduce to 320, 500, 800, and1000. Finally use a coarse and fine compound. If this does not work, then it is a new piece of acrylic.

 

[colind3782]

Before going mechanical, try Pledge or similar. I found it worked well on my aircraft windows after dumb pilots used paper towels on them!

 

[Deleted member 36384]

I used to work in a polishing shop. I operated the sand blasting cabinet and the perspex screen eventually dulled out. I would hand the screen over to the polishers who buffed it clear again on their mops using very fine soaps. It can be done.

 

[penfold]

If you have a less vital crazed bit of perspex to experiment with it might be worth having a play with really horrible solvents(methylene chloride etc) painted on, they might melt the crazed layer and rehomogenise(is that a word?) it. Or it might got horribly wrong and turn opaque. Definitely need to experiment first.

 

[Quandary]

I have tried it experimentally using very agressive abrasives mechanically to start, the crazing goes much deeper than the appearance suggests. Surface scratching, wear or cloudiness is much easier to remove.
No harm in trying but even with it flat on a bench you are probably wasting your time.

 

[2Tizwoz]

I have tried it experimentally using very agressive abrasives mechanically to start, the crazing goes much deeper than the appearance suggests. Surface scratching, wear or cloudiness is much easier to remove.
No harm in trying but even with it flat on a bench you are probably wasting your time.

I found polishing with an orbital sander and cream cleaner on a sponge polished out some of it but overall it was a failure and, having wasted some time and effort, I just replaced it.

 

[dankilb]

Our sliding companionway hatch (and curved at that) is bad. It also sports some gouges from over-long screws previously used to hold the life raft.

I doubt anything would reasonably get deep enough to get the lot out. And having a new one fabricated to take the curve is surely a faff.

I wondered about fairing it off with some epoxy and covering with exterior window tint film?!

 

[emandvee44]

If you have a less vital crazed bit of perspex to experiment with it might be worth having a play with really horrible solvents(methylene chloride etc) painted on, they might melt the crazed layer and rehomogenise(is that a word?) it. Or it might got horribly wrong and turn opaque. Definitely need to experiment first.

Yes I have the other broken panel to experiment on it is at home so I will have a go. Not too hopeful after reading all the replies. Thanks.
M.

 

[penfold]

Our sliding companionway hatch (and curved at that) is bad. It also sports some gouges from over-long screws previously used to hold the life raft.

I doubt anything would reasonably get deep enough to get the lot out. And having a new one fabricated to take the curve is surely a faff.

I wondered about fairing it off with some epoxy and covering with exterior window tint film?!

Putting a curve in acrylic isn't that bad; there are two requirements, a means of heating the acrylic to floppyness(ideally an oven, although domestic ovens are too small for most companion way hatches) and a plywood mould with the required curve.

 

[dankilb]

Putting a curve in acrylic isn't that bad; there are two requirements, a means of heating the acrylic to floppyness(ideally an oven, although domestic ovens are too small for most companion way hatches) and a plywood mould with the required curve.

That’s reassuring! I’ve seen people make slight curves with heat guns in thinner stuff (light aircraft windows again… a theme!). Proper oven heating hadn’t occurred to me.

Hopefully the old hatch can be used either as the former itself, or as a basis for making one.

I’d assumed it must be do-able because it’s a common setup (late ‘80s Jen) and I’m sure many more exacting owners wouldn’t put up with the state they get in. It does affect ‘doorstep’ (‘bridge deck’?!) appeal, as one of the first things you see when arriving back aboard.

 

[Plum]

Our saloon hatch acylic is crazed. Close examination shows that the crazing only penetrates a few microns. Before I order a replacement, has anyone any experience of restoring a crazed panel, and if so how?
View attachment 124000
The stripe is where previous owner had put non slip strips - coded boat, nanny state?
Thanks,
M.

When ordering new acrylic please note that not all acrylic is of the same grade with respect to uv inhibitors. Some will start to discolour or craze in 5 years, whereas clear cast Perspex® acrylic sheet, for example, is guaranteed for 30 years outdoors (the Perspex name is printed all over the protective film). I bought mine from www.simplyplastics.com 5 years ago.

www.solocoastalsailing.co.uk

 

[KAM]

My curved 20 mm hatch looked like that. I used a belt sander on it. The crazing was only about 0.5mm thick. The main problem was that it tends to overheat and drag. I finished with wet and dry used wet then Farecla. Just stuff I had lying around. Got a bit bored so just left it with a slight matt finish which was quite pleasing and far better than the crazing. You're not going to make it worse.

 

[emandvee44]

When ordering new acrylic please note that not all acrylic is of the same grade with respect to uv inhibitors. Some will start to discolour or craze in 5 years, whereas clear cast Perspex® acrylic sheet, for example, is guaranteed for 30 years outdoors (the Perspex name is printed all over the protective film). I bought mine from www.simplyplastics.com 5 years ago.

www.solocoastalsailing.co.uk

One of my problems regarding a replacement is that I am in Spain, and the suppliers for Lewmar are in UK. A new acrylic is expensive with import duties. I found a local firm that can copy the original if I need to go that route. I will try to restore it if an experiment on the broken panel is successful. Your advice re material noted - thanks.M.

 

[LittleSister]

The crazing in the OP's photo looks like UV crazing, so this warning is only tangential to the thread, but note that some polishes will cause acrylic to craze. I think it is using silicone polishes that is to be avoided, but can't remember for certain - perhaps someone can confirm.

For example, the dash of my car is badly crazed - mainly long semi-parallel lines looking like cracks - where some previous owner (or the garage that sold it to me!) has used the wrong type of polish. It's not a big problem, just slightly unsightly, most of the time, but when sunlight catches it at certain angles I can't read the speedo or make out other indicators.

So some people who are trying to care for their windows and other acrylic, and make it look nice, are unknowingly actually permanently damaging it.