Unglazed pottery oil lamps leaking?

[tombear]

Having aquired two or three replicas of Classical world unglazed oil lamps I someties like to use them, usually with the cheapest olive oil we have and linen wicks. in short order they leak as the oil soaks through so in the past I have kept them on top of ashtrays.

Back in the day lead (or brass, if I remember right) holders were used so having aquired a bit of roofing lead to provide nose weights for my silly stick and tissue planes I decided to knock one up.

It was simplicity itself, I cut a piece of one inch floor boarding just larger than the lamp and used a hide hammer to beat a piece of lead around it, making a tuck at the pointy end and beating it flat.

once it was to shape I gave it a quick rub all over with a tommy bar (anything smooth and hard would do and used a carpenters guage to mark a line to trim to to get a even top edge. The handle is simply folded back and at some point I will solder it in place. Very easy to do and it would be possible to do in recycled tin (big oil cans from behind Indian restaurants would be ideal) but you would need to make more tucks. The lead was easily trimmed with heavy duty scissors.

The maker of the lamp on the right mentioned to me that if I coated the inside with beeswax the oil would not soak through so quickly so I tried that, I melted about a tablespoon of raw beeswax pellets on my shed single ring hob and plonked the lamp on it as well to heat up so the wax wouldn't set as soon as it hit it. The inside of the lamp absorbed it all and 3 days later no oil has leaked through. It burned for 3 hours one night and the heat didnt cause any leakage. However since its olive oil the nurse has in the past told me to use to remove ear wax and I have melted beeswax in various fats to make dressings and what not I think the beeswax will eventaully fail on me.

Since at that point I hadn't seen images of real ones (which are quite chunky and tall like the larger sort of fishing weight or small bobbins of cotton but made of lead. I made the wick holders from the same lead sheet, chopped out with wad cutters then plenished (?) over the ball pein part of a hammer held up right between the soles of my feet as I sat on the floor like i'd seen on TV. Dspite not being authenic its worked well with a wick made from linen string.

Perhaps because of the purity of modern olive oil they burn a lot cleaner than the books say until you blow them out and if left unsnuffed smoke and stink the place out.

The open topped sort of lamp would be very easy to make in the field from clay and would work fine with any slushy cooking fat so long as you warmd it up on the fire to make it liquid and then didnt put it anywhere where it was cold enough to overcome the heat it generates itself while burning that will keep the fat liquid enough to pass up the wick.

ATb

Tom

PS wick holders have also been made from chalk and ceramics, If I had any lumps of real chalk I'd have a go. I'll see if theres any big lumps of broken plant pot out back to file and drill to shape, not having any broken Samian or a amphora to hand...

 

[JohnC]

Thats very handy, weve had the same oil soak issue with a lamp my son made at an archaeology day, but we'd like to use it. Ill give the lead dish a go.

 

[British Red]

Wow - I love these posts Tom - great to see people actually doing interesting thing

Wad cutter????

12B and 410?

 

[tombear]

They are dead easy. Looking at others on the net, most have higher sides and thicker walls, some look to be cast, so theres a wide variety out there.

I'm suprised how well the waxing the insides has worked. I wonder what dunking a hot pot into a vat of molten wax would do to it, may try it next candle making session.

ATB

Tom
Uw, must have posted just after you Red, I mean a wad punch

http://www.tooled-up.com/Product.asp?PID=6130

bought a month before I got that lovely set of leather workers punches for a song,, which is typical

In Shotgun, about 5 gauge for the biggest one...

 

[Toddy]

Neat very neat

Two things come to mind.

Firstly, unceramicised pottery, i.e heated until it bakes hard and useable, but not fully changed into 'stone' type stuff, is common in the past. Look up Barvas ware for the indigenous stuff. When we excavate this stuff when it's wet we call it 'rotten pot'; it crumbles away as we work.
Basically it's not kiln fired, but it's hearth fired. In the Hebrides, where the tradition survives (I know a lady whose Aunt still makes it at a round house/black house heritage centre) the pot is made, dried as dry as possible sitting near the fire and then it's actually place into the fire (peat in this case) and filled with hot peat ashes too. Eventually it's removed from the fire and then milk is poured into and over it.
The milk lipids seal the pot and make it non porous. Once this is done it can be used to store liquids, cook in, drink from, without leakage.

Might work with your little oil lamps too I think if you heated them up slowly in the oven they ought to be hot enough for it to work.

The second thing is that there are many, many stones in the UK that can be carved with simple tools. Greenstone, serpentinite, steatite, some of the schists, and slate and cannel coal. The Egyptians worked slate to make palettes for painting and for makeup, all beautifully shaped and hollowed, the Vikings who were largely aceramic, used steatite (soapstone) to make their pots and cooking vessels. In the NE of Scotland Serpentinite has been carved for millenia.....and the list goes on and on.

I have some serpentinite Tom, I'll see about finding it (it's in the bottom shelf of the last shed that I need to clear out ) and getting some down to you, and I'll find a bit for you too John

You might have a word with Gary if he doesn't see this thread; he uses oil bowl-lamps in his Grubenhause in the Dark Ages village near York.

atb,
Mary

 

[British Red]

Uw, must have posted just after you Red, I mean a wad punch

http://www.tooled-up.com/Product.asp?PID=6130

bought a month before I got that lovely set of leather workers punches for a song,, which is typical

In Shotgun, about 5 gauge for the biggest one...

Looks like the same thing - just the sizing that is different I suspect - what does one use the wads for (other than in shooting)?

Sorry Off topic I know!

 

[tombear]

Red- I mainly use them for making leather washers and rubber seals but have used then for putting holes in thin brass, alluminium and tin sheet also the kids and I have used them for making plastic bases for glorified toy soldiers legs ona cardboard dinausaur (Stacked) the shields on a Vicking long ship (with split lentils as shield bosses). If I ever get around to getting a black powder license etc I will even use them for wads!

Mary- as ever wonderful stuff. No hurry on the serpentinite but aye, I look forward to having a play with that. I did try and get some soapstone but the only place local wanted what I thought silly money for a rock. In the end i found a 99p trinket pot in a charity shop, chucked the lid and cut the sides down to make this.

The wicks linen rope and its burning fish oil which smokes much more than the other stuff i've tried. Anyroad its lovely stuff to work, my normal files leave a smooth finish. Theres some cottony type sead heads the vikings used to twist into wicks I'd like to find, need to do a bit of research so i reconise the plant and know when its the right time to collect it. I must start making proper notes!

One of herselfs relations gave the boys a sack of clay which is still unopened, i will have to get the artistic one to have a go at copying some lamps, saying that the soils pretty clayey around here with bright yellow lens if you dig down.

By The way still not found the 4 small plates but I'm narrowing it down, Yesterday we did Bolton Car boot and she came back with 38 pieces of Denby, The charity shops are nearly all open on a Sunday now and almost everyone had single pieces or groups of 8 as well as what was on the stalls. All I got was a 50p wooden bowl... Oh and a 14 inch Gilbow universal tinsnip for 50p thats cleaned up lovely. I nearly fell off my perch when i saw how much they are new!

ATB

Tom

 

[British Red]

Red- I mainly use them for making leather washers and rubber seals but have used then for putting holes in thin brass, alluminium and tin sheet also the kids and I have used them for making plastic bases for glorified toy soldiers legs ona cardboard dinausaur (Stacked) the shields on a Vicking long ship (with split lentils as shield bosses). If I ever get around to getting a black powder license etc I will even use them for wads!

Makes sense...hadn't thought of washers . Just bought a 12 bore cartridge sized wad cutter for "rolling my own" 12 bore cartridges.....something else to play with and understand

 

[oldtimer]

Toddy's post explains the relationship of porosity and firing well. However, even well fired earthenware vessels can seep oil if not glazed. Porosity depends on the firing temperature and not all clays will withstand being fired at a high enough temperature to make them seep proof. I used to make unglazed earthenware lamps with children and students more for history teaching than pottery. I used to cheat by using a clear varnish to the outside of the lamp. Oil would still seep into the clay, but not through the varnish. I wouldn't recommend this for foodstuff containers.

I've fired pots in a similar way to Toddy's description by using a brushfire as is done in Africa: it works but there is a high failure rate. I've never heard of the milk trick, but it may well work by filling the pores in the clay. I suspect it would need to be renewed from time to time.

Interesting thread.

 

[oillampman]

your original Caerleon oil lamp pictured here was defective in my opinion not fired quite high enough by the looks of it. I have now become Caerleon's supplier and ours are less leaky than the originals we fire to 1020 which Im assured some of the better roman kilns could have reached this does limit the leakage though it does not eliminate it

 

[oillampman]

your original Caerleon oil lamp pictured here was defective in my opinion not fired quite high enough by the looks of it. I have now become Caerleon's supplier and ours are less leaky than the originals we fire to 1020 which Im assured some of the better roman kilns could have reached this does limit the leakage though it does not eliminate it