I found a posttop lantern that have a PMMA (acrylic) bowl, or atlest looks like PMMA

The lower section of the bowl is broken into few pieces (some large, some small), but i got all of the pieces that complete the bowl so i want to glue them together

The PMMA is diffused white, somewhat yellowed and rough from 25 years of UV, but only on the surface, in the thicknes the material is still good as seen in the edge of the pieces

I want the glueing to not stand out very badly (the pieces line up well with each other so i dont need any thickness of the glue), to be reliable, long lasting, and sturdy enough (the bowl also supports a large metal shade)

Thought of using cyanoacrylate

 - Is cyanoacrylate (super glue) suitable for the task ?

 - How much is the strength compromised ?

 - The lantern is originally 150W SON-T, that is quite marginal for the lantern even in good condition. Is the glue at risk of going apart from the heat ? Is it better to convert it down to 100W or 70W SON ? (100W is easy conversion, 70W not so much because i will have to hack an E27 socket in a place that have the screw holes for E40 only)

Could you use RTV silicone glue to put the pieces back together? The only obvious drawback is that its flammable when it's wet.

RTV is good on large surfaces, not for matching thin edges

How thick is the bowl plastic?

3 mm

I'd use superglue and then put the rtv silicone over the cracks for extra sturdy.

It wont really add much, but if i wipe a "band" of RTV it will be more noticable and that i want to avoid (i want to hide the cracks as much as possible, so better if they remain only the crack hairline itself with the superglue)

Thing is, will the superglue last ? And how will it react to the heat of 100W..150W SON-T (HPS) ?

I'm not sure. It may depend, since some brands of superglue vary on the outer limit of their functionality. You could do some research and find clear heat resistant adhesive, which should be available at a hardware store or online. There is also heat resistant gorilla glue that may work.