56 replies to this topic

[BrightStar]

I have a really odd experience from last night to report... I was testing a 2" length fountain and picked up the tube after the burn. From being rock hard, it had gone completely soft - I could crush it mid-length between thumb and forefinger with no effort at all

The meal in the comp was intentionally low quality, made with cheap mixed charcoal, damp milled for an hour or so. The fountain tube was homemade 3/4" id, approx 3.5mm thickness virgin Kraft, bonded with builders PVA thinned with a dash of water.

I can't decide whether this was a thermal effect on the PVA glue, or something caused by the remaining moisture in the meal powder (which was never completely dried due to bad weather) generating steam in the tube. Either way, it seems relevant, and could surely cause a rocket CATO etc... Today the tube is rock hard again. Any ideas?

Edited by BrightStar, 04 September 2006 - 04:16 AM.

[EnigmaticBiker]

I have a really odd experience from last night to report... I was testing a 2" length fountain and picked up the tube after the burn. From being rock hard, it had gone completely soft - I could crush it mid-length between thumb and forefinger with no effort at all

The meal in the comp was intentionally low quality, made with cheap mixed charcoal, damp milled for an hour or so. The fountain tube was homemade 3/4" id, approx 3.5mm thickness virgin Kraft, bonded with builders PVA thinned with a dash of water.

I can't decide whether this was a thermal effect on the PVA glue, or something caused by the remaining moisture in the meal powder (which was never completely dried due to bad weather) generating steam in the tube. Either way, it seems relevant, and could surely cause a rocket CATO etc... Today the tube is rock hard again. Any ideas?

Difficult to say really.
Was it really dry to start with? (you mention damp powder/weather)
Was it really hot to the touch or just warm?
Could it have realistically have dried out where you left it?

Combination of both is my guess.

I've had problems with "PVA" glues (they are a blend of PVA, EVA, and other polymer resins).
A really cheap industrial sample dried tacky if diluted and became unstable in the container, discolouring after 2yrs storage. Another, a retail, builders PVA sealer dried tacky as well (when diluted) and wasn't very water resistant.
The solids content of these adhesives vary with the cost, as will the blend.

I go for undiluted waterproof woodworking PVA and the main problem I've had is sticking to the rod I'm rolling it with.
[size=3]

[Silverturk]

I'm just using normal wooden glue, because it's easy to roll and becomes really hard. Yesterday i rolled a 1'' ID tube for launching a really small shell, and the wall thickness is about 3 mm, and it's so hard I can't even deform it with my fingers! No matter how hard i try. And my 1/2'' ID tubes for rockets has a wall thickness of 5 mm, and I can even stand on them without deforming it! The only thing I can do to deform the tube without using any tooling is to bite on the edge - they are then being bent a little. But the tube is getting back it's old shape as soon as I release pressure.

One thing makes me wonder;
Everybody here seem to paint the whole paper with glue before rolling. When i do this, the glue immediately soaks into the paper making it all full of wrinkles. The glue also stops being so stiffy as it used to be.
Instead, I put a thick string of glue across the paper (just as i start rolling the tube) just in front of the dowel. Then I push the dowel down as hard as I can and start rolling. All excess glue is then squesed in front of the dowel as I am rolling. A little glue is squesed out at the sides, but it's not much and it's easy to remove. Using this method takes a lot less glue compared with painting the whole paper in glue.

If you use "my method", remember to stop rolling and add more glue if it runs out at a small spot, ex. in the middle. If you just keep rolling untill all glue has been rolled in between the paper layers, you will end up with a hard tube that has a really thick wall which is full of air bubbels.

Edited by Silverturk, 06 September 2006 - 07:29 PM.

[fishy1]

Has anyone tried making paste the way wiengart mentions? I.e Mixing the flour and water, letting it go "sour", so their's a top layer of liquid, and a bottom layer of pastey stuff, skimming off the top layer then mixing the bottom layer with boiling water and stirring until it thickens? It says this paste is pretty good and keeps for a month.

[fishy1]

I tried the previously mentioned method.

I put 500g or so of cheapie (plain) flour in a plastic cup.
I then added about 400ml water and stirred. I made a lumpy not properly mixed paste. It looked like awful paste.
Then, I left it in the shed for about 4 days. I came back, there was about 5mm depth of liquid on top, below it there was some floury paste looking stuff. I tried to smell it (I have a terrible sense of smell.) It didn't smeel of much. I thought it might not be fully rotten as the shed wasn't at the 90degrees F weingart recommened, it was probably more like 5-15C varying through the night and day.
Next day, I came back. A brown crust had formed on top. Their was a strong smell of bread rising (yeasty smell). I stuck a knife in the crust and stirred it. It has a stretchy, doughy consistency like well kneaded bread dough. I also noticed there were bubbles of gas being given off.
I added about 100ml more water and didn't stir it.
Two days later, I came back. There was a layer of waterly liquid that I poured off. The bottom layer of liquid was poured into a pan. It has a consistency like crepe batter.
I wasn't sure what a faucet was but I reckoned it was a tap for hot water. I wasn't sure if weingart meant to put the paste in a double boiler, so I didn't bother.
I got boiling water and poured it in. I stirred it vigorously. It got thin like milk. I kept adding water and stirring. After adding about 2L of water, it still hadn't thickened so I modified the recipe. I whipped out a trangia stove and heated the milky liquid on it. I stirred constantly. It got a little thicker. I was paranoid about "overcooking" it as I had never made paste like this. I lifted out my stirring fork and little lumps were stuck to it. Ah no, I'd overcoked it. Unless, I thought, It was like making white sauce and it would go lumpy before all of it thickened. I thought I'd just keep heating to see if I was right. It got lumpier and lumpier and became like undercooked scrambled eggs. I kept mixing and it eventually became more even. Then, just like that, the whole panful became very thick and lumpless. It was too thick to pour, so I poured in a pint of cold water. Mistake! It curdled horribly but I kept stirring it and it fixed itself. One problem, it was still too thick. More water was added and again it curdled and again I fixed it. It was getting pitch dark so I poured the paste into a few jars and screwed the lids of tight. I went inside and watched TV.
The next afternoon, I came out. I was fearing it might be covered in mold (warm floury paste seems a pretty good enviroment for mold to form.) My suspicions were destroyed. It looked fine. On opening the jar, the "paste" was more like jelly. You could certainly have eaten it on toast if you felt like it. I don't recommend it. I added more water to each jar and stirred. It became thinner with a bit of effort. It looks excellent, nice and lumpfree. It's very sticky. The pan was a nightmare to clean. The paste was really stuck on but it came off eventually.

I made a 3" shell and did the first bit of pasting with the paste today. It's drying but the paste was very easy to work with and stuck the paper down well. Can't wait to see what the shell's like.

[EnigmaticBiker]

Has anyone tried making paste the way wiengart mentions? I.e Mixing the flour and water, letting it go "sour", so their's a top layer of liquid, and a bottom layer of pastey stuff, skimming off the top layer then mixing the bottom layer with boiling water and stirring until it thickens? It says this paste is pretty good and keeps for a month.

I'm interested in the going "sour" process, wonder what's going on there then?

Having read what you did to make it, it seems like a lot of hassle for starch based glue; Then again I am inspired to try a rice based one to see what happens.

"It's very sticky. The pan was a nightmare to clean. The paste was really stuck on but it came off eventually."

Best not to use an aluminium pan, as Al can thicken it and NaOH (caustic soda) can then be used for a quick cleanup afterwards.

[fishy1]

I'm interested in the going "sour" process, wonder what's going on there then?

Having read what you did to make it, it seems like a lot of hassle for starch based glue; Then again I am inspired to try a rice based one to see what happens.

"It's very sticky. The pan was a nightmare to clean. The paste was really stuck on but it came off eventually."

Best not to use an aluminium pan, as Al can thicken it and NaOH (caustic soda) can then be used for a quick cleanup afterwards.

It's excellent stuff this paste, very sticky and lumpless. It's a bit of work but it's only really 2 hours max(+waiting time) and that sets you up for a lot of paste.

I used a steel pan.

[EnigmaticBiker]

It's excellent stuff this paste, very sticky and lumpless. It's a bit of work but it's only really 2 hours max(+waiting time) and that sets you up for a lot of paste.

I used a steel pan.

Didn't want to mention cleaning up with caustic without checking the pan material, it EATS Al nicely.

Not surprised it's good, a lot of starch is used industrially, usually from crisp factories.

I'm gearing up my tube production for Nov, making good cones is slow though.

[fishy1]

Didn't want to mention cleaning up with caustic without checking the pan material, it EATS Al nicely.

Not surprised it's good, a lot of starch is used industrially, usually from crisp factories.

I'm gearing up my tube production for Nov, making good cones is slow though.

Ah yes, Al foil and NaOH solution is always fun for making hydrogen.

I didn't really want to use caustic as I can't be bothered with the hassle of eye protection/gloves etc. Also, then I'd probably have to do it outside in case I tipped the pan over or spashed any.


I've only done in one Al pan. and that was when I was misinformed it was steel so I melted lead in it. It now has about an inch hole in the middle.

Edited by fishy1, 25 September 2006 - 07:49 PM.

[EnigmaticBiker]

Do you leave your tubes to dry on the former (Broom handle/ aluminium rod) or slide them off straight away?

I've tried both methods many times and always seem to have problems getting them off.
Maybe I'm rolling them too tightly?!?!

I had the sticking problem, especially with a tight tube.

A smear of petroleum jelly helps.

Sometimes the tube would slowly bend as it stiffened up so I re-insert them until it's dry.

[phildunford]

I find the secret to getting tubes off is to make sure you have loads of glue on the former itself, it then slides off really easyly.
I would not recommend leaving a tube on the former - would be hard to stop it sticking - you would also need alot of formers

[EnigmaticBiker]

I find the secret to getting tubes off is to make sure you have loads of glue on the former itself, it then slides off really easyly.
I would not recommend leaving a tube on the former - would be hard to stop it sticking - you would also need alot of formers

I suppose it depends on the glue used, I'd agree with you if it was a starch based paste.

The waterproof woodglue I use starts to set really quickly and even sticks to stainless steel rods (printer rollers), on varnished wood even faster. So a wax or greasy coating helps.

When I first started rolling tubes they often warped as they dried, so when they were partly dry I put them back on til they were completely dry. I'm a bit better at it now . The problem was that different areas of the paper absorbed more water than others, distorting it.

Edited by EnigmaticBiker, 20 October 2006 - 09:38 PM.

[aquarius]

My way is simple but effective:

I am using kraft paper, 50/50 good wood-/ cheap wallpaperglue and steel/alu rods for the work.

Roll them up, kutting while still moist on the steelroller (much easier to cut), slide them off and let them dry om the aluroller.
The space betewwn each tube also seems to speed up drying, since a bit of moisture escapes there.

I will try "Manilla folder", but a bit unsure of what it actually is.
Are we talking about the thick paper used to divide papers in a "ring portefoil"?