How can I clean fixed plastic cabin portholes

[RJMRJM]

My clear perspect cabin lights are fixed in external aluminium frames the perspect is about nine years old since i last replaced it and is not crased or scarred in any way but is streaked from weather which appears to run off the aluminium surround at the top. I have tried several plastic polishes including 3 M but nothing seems to do a good job of really cleaning the clear plastic,. Has anybody found the solution This must be a common problem on many older boats pre stainless porthole frames.Many thanks for all help

[tkeithlu]

My chemist wife tells me that even Reynolds Aluminum used to scrape aluminum oxide off the windshields of cars at its factory, because there was no chemical way of removing the stuff. That suggests that Micro Mesh, which is sandpaper for removing crazing in aircraft acrylic windshields, and similar to the kits for automobile headlight lenses, may be your best bet. I've done it to an airplane - it's an afternoon's work, but not all that difficult.

[Chotu]

What about buffing it out?

This is more a question than advice. I was going to buff out some permanent marks I have in some polycarbonate made by relentless Florida mold.

[1affiah]

IMHO buffing creates too much heat, and is a circular motion. I tried buffing my headlight lenses, I had to resort to micro mesh kit starting at 220 to fix that, plus MM kit states cross hatch pattern alternating each grit. +1 for MM.

[thinwater]

Originally Posted by 1affiah

IMHO buffing creates too much heat....

With the correct method you can buff soft vinyl windows.

• Keep the bonnet wet. Keep a spray bottle at your elbow.
• Low speed.
• Light pressure.
• Stay out of the sun if possible.

Very little heat.


Not sayin' that starting with sandpaper is not the right answer is severe cases. It is.


In the OP's case, if runnoff and aluminum oxide may be part of the problem, I would start with dilute hydrochloric acid and do my best to keep it off the aluminum (wipe with rag, mask frame). The problem with most weak stain removal acids for metal stains on boats is that they are specifically inhibited NOT to remove aluminum, because in most applications that is very bad. But in this case it is what you need.

[tkeithlu]

Use MicroMesh rather than a buffer for this job. The problem is the technique. A buffing wheel will leave you with swirl marks, even if microscopic. With MicroMesh you sand in one direction with the coarsest (extremely fine) sandpaper, then 90 degrees to that with the next even finer, and so on. The result is clear vision, even if you end up with microscopic grooves - they are all oriented the same way. That's why it's used for airplane windshields.

[er9]

i agree with trying mild buffing first.

a mild but very effective way to buff surface grime and stains on plastic is to get a small 4-6" random orbital sander with velcro pad. go to a local fabric store and pick up some acrylic felt. cut a disc of felt to fit your velcro sander pad. cut the felt about 1/4" bigger than the pad. grab a bottle of Novus #2 polish (more effective than 3M polish).

add a dab of polish to the lens and buff away, repeat if necessary. if the stain hasnt absorbed into the acrylic/plastic it will remove it. if this method cant remove the stain you will have to resort to sanding and more aggressive buffing. the nice thing about the felt/random orbital/novus system is that it can be used to buff clean any plastic aboard and is very good for restoring vinyl dodger windows. its very mild on the plastic. we use it as part of a final finish buff for acrylic furniture.

before buffing, clean with mild cleaner to remove loose surface dirt first so you dont turn your buffer into a sander. especially necessary to do this before buffing vinyl.

[Mithril Bham]

I face the same challenge with lots of old plexiglass. I saw a Utube video showing someone using a Multimaster with polish. Sure looked like it worked well. I don't have the link but should be easy to find. I'm going to give it a try. Maybe it's time to remove and re-glaze.
Good luck.

[Mike Banks]

Colgate's Toothpaste and some elbow grease.

[mvmojo]

Micro mesh worked on my 25 y/o port lights.

[oceanshoretiga]

I use Brasso to clean my portholes. Rub it on and rub it off by hand, no power buffer in my case.

BTW, thanks for all the other ideas. What is micro mesh?

[RJMRJM]

Originally Posted by RJMRJM

My clear perspect cabin lights are fixed in external aluminium frames the perspect is about nine years old since i last replaced it and is not crased or scarred in any way but is streaked from weather which appears to run off the aluminium surround at the top. I have tried several plastic polishes including 3 M but nothing seems to do a good job of really cleaning the clear plastic,. Has anybody found the solution This must be a common problem on many older boats pre stainless porthole frames.Many thanks for all help

Many thanks to all for your suggestions I recall that when these ports were put in they had work marks which in the main the fitter removed with a buff and polish but the finish obtained despite several attempts was less than perfect. I will try the toothpaste first If not successful next will be the Brasso then the sandpaper if all else fails. This still leaves me with the ongoing cause of the problem that is the ageing aluminium frames not all of which are causing a problem .Would the same cleaning system help there also and thanks again for the help

[mbinns]

I just used an automobile headlight lens cleaning kit from the auto supply store, followed the steps on instructions and it worked great.

[RJMRJM]

I have now purchased some lenze cleaner from the aoto shop so that will be my next attempt tomorrow seeing all other attempts have failed Will let you know how i get on

[RJMRJM]

I used the auto lense cleaner on the portholes and for the most part it did the job, not perfect but pretty good so now I have to find some way to treat the aluminium surrounds to stop these stains occuring in the first place. ANY SUGGESTIONS.