I think I'm not gonna get the Ebay ones, as I've got no experience with that, or comparison to other genuine lamps, and I don't want to spend £170 thinking I got something safe while it might be quite the opposite.I think you are very wise to put this kind of effort into finding a good lamp. A bad lamp is such a headache and the potential for a sensitizing reaction is serious. There's not a lot of studies out there but studies suggest that less than 2% of the population is sensitive to acrylates, but among dental professionals the rate jumps to close to 25% (http://www.journal-imab-bg.org/issue-2013/issue4/JofIMAB2013vol19b4p363-370.pdf). That's telling because many of the compounds that we use in the nail industry come from the same methacrylate and acrylates in dental compounds. So, I think that tells us that the potential for developing an allergy due to constant exposure is significant - constant exposure though can mean one who works with these compounds, but can also mean someone who wears uncured gel for long periods. So it's worth being careful.
Red Carpet Manicure is made by the same company that makes Gelish is it is considered to be identical to Gelish; even the colors are dupes. It is a well regarded brand and an excellent option for DIYers. I don't know why the Gelish 5-45 and RCM Salon Pro 30 have different timings even though they have the same wattage, but wattage is only a sign of input not output. Also, the design of the lamp - hand placement, reflectors, etc. does make a difference.
The lamps you show look genuine, but check the seller's feedback - that's a dead giveaway. I have found quite a few deals on lamps on eBay - students, salons, distributors selling extra lamps. Assuming you buy a lamp of equal configuration to the manufacturer's, I'd go with the manufacturer's timings. So, for example, if you buy the Gelish 18G, use a 30 second timing on your OPI, but if you go with the Gelish 5-45 (a lesser l amp), use the lamp's timings.
So I think I'm back to Gelish 5-45 vs RCM Salon Pro decision, but the timings got me really confused.
If OPI should be cured for 30 seconds in Gelish 18G, than what should I do if I get the RCM one? It's a weaker one, and yet claims to cure in 30 seconds. So I would assume it won't cure OPI well in 30s?
Since the Gelish and RCM polishes are the same, they should take the same time to cure.
Times for Gelish 18G:
foundation - 5 seconds
colours 20-30 seconds
Top it off - 30 seconds
Gelish 5-45
Foundation, colour & TIO - 45 seconds
Gelish Mini
Foundation, colour & TIO - 45 seconds
And then wasn't 6G also curing in 30 seconds?
and what about 9G?
Regarding OPI, you say "a lamp of equal configuration to the manufacturer's" but how do you judge if it's equal if it varies SO MUCH?
I absolutely don't get how it works.
I'm starting to think it's nearly impossible to get it right.
Like, what makes 18G cure foundation in 5s and colour in, say, 20s if all those need 45s in other lamps? Unless 18G is both emitting different kind of wavelengths than 5-45 and the foundation responds to different wavelengths than colours it just doesn't make sense to me.
And then wattages either don't mean anything (Mini is 6W and 5-45 is 18W!) or even Gelish people have no idea?
It's strange though, because I know what Doug Schoon says about wattages, but they do actually mean something. He may say that his 1200W hairdryer wont cure the polish, but it's a little bit silly logic to me. Watts have of course nothing to do with UV emission per se, but generally if it takes more energy the output is usually stronger. This is not to say that I don't believe that lamp design can matter a lot, it just confuses me how those times seem consistent with... nothing.
If £100 RCM lamp cures in 30s, than what are we all doing considering lamps like OPI or 18G?
I mean, seriously, how the hell do I get it right?
TBH, I would assume it's best to stick to lamp guide regarding cure timings, because it would seem to me, that it's more lamp-related than polish-related.
So basically, Gelish cures under 18G, or any of their other lamps, and the time differs from lamp to lamp. And then Gelish also cures under RCM lamp for 30s, because, well, RCM polishes are Gelish ones. And also under the OPI lamp, as they say off record.
I'm going crazy!
And then...
Is it better to over cure? That can cause onycholysis, but I'm not sure if it happens when the polish is 15 seconds over cured or more like a few minutes.
How common do you think allergy is with people that just get gel polish every few weeks? I honestly didn't realise before the risk was so high.
I assume it's rather safe if you cure well, but then, again, I'm so confused about the timings!