Just punched the washers from silicone baking pan. They make the fuel caps beautifully tight. Now I have to put it in the kerosene and petrol, to check, is it really fuel resistant, as they wrote...
I keep it quiet... (you know, wooden block locked in the vise, etc. ) BTW, IKEA silicone gloves are thicker than this baking pan. My wise child made an experiment with one: "is it REALLY fireproof?" and put it in the gas flame. The edge turned a bit dark... It will be a good excuse to buy a new one...
Experiment and results: - I put punched inner parts of silicone washers in paraffin for two days. Washers submerged in paraffin increased their diameter from ca. 8mm to ca. 9,5 - 10mm. So, the sources were wrong, or it's a wrong kind of silicone... I wonder -- is it reacting in similar way with butter/oil in the cake? And what do you eat? As material for washers in NRVs and others -- a 'jeep' cannister seal should be OK -- it's guaranteed fuelproof and costs a little...
Good inspiration here. Does the cake-form come in green? I serious need that for my Lightbrand (china-lamp) where the tank-lid-seal is green. Claus C
Well, are you ready that it will expand and turn into green goo? In IKEA I've seen pale-green, as pistachio icecream. Maybe you'll find a properly coloured spatula for "licking" the cream from the bowl? Kitchen utensils in general are in warm coulours -- red, orange, sunny yellow, purple -- warm coulours are good for appetite (green goo in nature is usually un-edible, or edible only once... )
Mark Why does chinese put green rubber inside a lamp - how do they think that - and giving me this problem to expose Claus C
Probably colour is a chrome-oxid (as in polishing paste) -- very fine and hard particles. The gardening tools, benches in parks, etc. were painted in this colour. It was making paint resistant, so it could be with rubber, probably.
I was just looking at some silicon rubber sheets advertised on the bay of evil as gasket sheets and the specifications noted: " SILICONE RUBBER IS NOT SUITABLE FOR USE WITH PETROL CHEMICALS, AS IT WILL CORRODE QUICKLY ". So that looks like the end of this little experiment...
Viton is the best stuff. Nitrile 'should' be ok but the percentage of actual nitrile is usually so low nowadays that gasoline & kerosene fuel will penetrate & destroy the non-nitrile constituents of the rubber turning it to mush - especially if the rubber is compressed, as in a filler cap. You normally have to find out the hard way as I know of very few nitrile suppliers who will openly say it is crap for our purposes. I think the actual amount of nitrile within the rubber to qualify it for the description of 'nitrile rubber' is just above 50%. Apparently at least one petrol pump manufacturer uses nitrile rubber but it is bespoke manufactured. I imagine that applies to other industrial uses where in theory nitrile should do the job. I've not had a modern non-Viton rubber washer set last more than a year. I was often renewing nitrile seals on some of my user lamps & stoves before every annual Newark gathering. Viton also has better UV resistance, so less or none of the cracking around the edge of exposed washers you often see on the vaporisers of Tilley's etc. I'm not a chemist. The above is based on lengthy chats with my long experienced supplier & my own fettling experiences.
This might explain something. I fettled all my FL6s prior to floodlighting the local church for the Queen's Diamond Jubilee celebrations in June last year using my usual nitrile sheet which had caused no problems in the past. Come Christmas Eve, I got them all out again for the same purpose, expecting them to need no fettling whatsoever. How wrong can you be! At least half of the little buggers were incontinent to some degree or other - bah! Looks like I'll be calling upon the services of The Fettle Box ere long...
Well, I'm on the side of the Spiritburner with respect to Viton v The Rest. I've found a Specification Sheet that compares common rubber-type seals and their properties under various uses (shore hardness, temperature, etc). When I work out how to download it in a way that it can be uploaded onto CPL I'll post it. In short, though, for anything that is in contact with fuels or solvents, nitrile and viton rate best (by far) with viton rating better over all categories...
Very true Tony. Viton is Viton though, a registered brand of fluoroelastomers. There are grades of Viton but as far as our purposes are concerned those grades range from excellent to way over the top! The grades of nitrile rubber vary considerably - from rubbish to very good. Most commonly available nitrile is at the lower end & most suppliers give scant info on the grade.
Nitrile is also susceptible to light exposure so I suspect even a good grade will deteriorate over time if stored badly...
I did some tests a few years ago with nitrile & viton in seals containers of paraffin & petrol. For some reason I still had the nitrile/petrol container in the workshop. I opened it at the weekend & the nitrile was just black slime in the bottom.
