How to identify a valve if the writings missing???

I recently got a box of preamp tubes and all are ecc81, 82, 83 etc, but some have most of the writing missing as it seems to rub off really easy off the old valves.
I have a brimar ecc82 and a brimar tube which i think is an ecc83 but am not too sure as the writing is missing - i think it may say 12ax7, but its so faint i can not be 100% sure, the plates look identical in shape and length to my brimar ecc82, but at the same time my mullard ecc83 tubes have the same shape plate.
Date codes that are etched on the glass can be useful, but there is little information on brimar codes on the internet.
So what i really want to know is, if i get someone with a valve tester, will they be able to tell me what type of tube it is by the strength of the reading? Suppose you test it as an ecc82/12au7, if it is an ecc83, would i expect a stronger than normal reading than a 12ax7?

Thanks for any info.

I have found that sometimes if you breath on the spot where the faint marking is the moisture from your breath will make the numbers visable for a short time.

Wow I was going to say that too but thought it was a bit "off the wall". But since you started it...

I put them in a fridge (or freezer for a shart time) then pull them out nice and cold and breathe on them. The glass where the paint was has different surface tension properties and you can usually see the writing in the tiny droplets.

thanks for that info

i will give that a try, but ive remembered that ive got a UV lamp and am wondering if that will show it up under UV light, ill let you know if it does.