Homework help please.. compression moulding

(13 Posts)
randgirl Mon 20-May-13 09:22:06

Hi all. Please can someone assist us with a project which ds has for this week for school. He has to make a mould (for a chocolate) using plastic which must also be insulated keeping the chocolate from melting and strong enough so it doesnt get squashed.

The whole day yesterday was spent trying to melt a plastic according to the brief from school. They were told to submerge a piece of plastic (no 1) then when its warm quickly until it softens then place into mould to shape it. Well every type of plastic we tried just curled the instant it was dropped into the water. We used all different type of plastic, (no 5 didnt even soften). Googling hasnt helped at all, they just say to melt it directly on top of double boiler, but the instruction was clear that it the plastic should be submerged in boiling water..

Typically dh is working away for 2 weeks so i cant even ask him for help.

Has anyones dc had a similar project to do and can offer some advise please?

tia

Lottie4 Mon 20-May-13 10:24:16

Sorry, can't help, but it's probably worth your son asking other pupils what they've been using, or if you know any of the parents give them a call. If not, get him to have a word with the tutor, explain so far nothing has been successful and ask if there is a book/website he can refer to for guidance! Hope he finds something soon. These projects can be a nightmare.

randgirl Mon 20-May-13 10:44:19

Thanks Lottie. All his pals are in other classes in his year and they havent done the project yet so his class are doing it first so all the other parents are just as clueless confused.

I have told him to ask the teacher today for clarification but tbh i dont know if he will. If he doesnt then there is little more i can do to help him, these projects will be the end of me i tell you angry.

monikar Mon 20-May-13 12:46:30

I remember these projects - never had to do this one though!

When reading your post, I immediately thought of a gum- shield as this is made of plastic, you place it in hot water to soften it and then put it in your child's mouth to mould it. I dont have boys doing contact sports, but i do remember friends with boys saying they could be bought inexpensively from sports shops - I don't know how much though.

The plastic would satisfy the brief from the school in that it would soften in hot water and then be moulded. Perhaps you could mould it into a suitable chocolate shape?

Hth - I always thought these homeworks ended up being done by parents rather than the children.

Startail Mon 20-May-13 13:40:03

Was the plastic provided by school? or are you meant to rummage round for it?

Surely plastic that softens in hot water will loose it's shape if used to mould hot molten chocolate confused

randgirl Mon 20-May-13 15:21:25

No the school dont provide anything... and the gum guard idea is a brilliant one, except it must be done from recycled materials. So we tried plastic from Coke bottle, tomato sauce bottle, diswasher bottle, ice cream container, an old plastic bottle i had that was different type of plastic. None of them worked. The chocolate has to be presented in this mould so the chocolate doesnt need to be melted to fit (afaik.. gawd lets get the notes out again.. angry.

I dont usually get so involved as ds usually does the projects alone, but he came to ask my help on this one. But why they do it like this i never know as you can be sure that most of the parents will have had a big part to play in them......

Racking my brain now to think what else that plastic is used for other than a gum guard.........

PeterParkerSays Mon 20-May-13 15:26:44

how big does the mould have to be? Could you use a bottle top.

Is there a set mould that the plastic has to be made to fit?

randgirl Mon 20-May-13 15:38:50

The mould must hold just one chocolate. He thought of using a tablet container and putting the soft plastic onto the lid of the container and then compressing it into the lid shape using the bottle part of the tablet bottle. The lid is slightly bigger than the bottle so it 'should' work. But it wont if the plastic is too thick. So i think it will be easier to find a chocolate to fit the mould than the other way around grin.

The chocolate must then been insulated so it doesnt melt, so he thought of then wrapping the whole mould in some of that shiny paper thats a bit like foil. To hold it in place i though he could just tie a ribbon around it. It has to look like a gift.... hmm

We should try a bottle lid.. i wonder if it will melt as its quite thick. Sigh..

Sebbywebby Mon 20-May-13 21:15:57

If it only has to hold a small chocolate, try an old store card. The thin ones. I use an old oasis store card ( the thinner the better) to demonstrate thermoplastics. Bowl of boiling water for a few minutes and you can bend it however you like. Scares all year 9 girls who think you have ruined your credit card ;) failing that have you tried a yogurt pot? Boiling water should be enough to shrink it a little in order to hold the chocolate.

Sebbywebby Mon 20-May-13 21:19:06

And have something ready to shape it around. You only have a quick window of time to shape it. Quality street could work to then fit inside. Lots of shapes to experiment with. Hope that helps.

randgirl Tue 21-May-13 08:07:33

Thanks so much everyone for the help and ideas.

We ended up putting a piece of plastic into the oven on a plate and it made is soft enough to mould with the tablet bottle. I know we havent gone according to the brief, but ds has now put the unsuccessful attempts into the written part of the project explaining why they didnt work. So imo as long as he tried to do it like they suggested, it didnt work so he will explain what happened.

PeterParkerSays Tue 21-May-13 09:31:14

Christ, how would kids have coped with this who didn't have a parent to help them?

What a blasted faff - how many pupils has this put off science?

Startail Tue 21-May-13 09:38:49

DD1 always says she likes things that don't work as they give you something to write up, but yes what a load if faff.

I had a thread about DD2 and the weather station she didn't want to build.

I hate HW for parents. I'd also like my memory stick back that the geog teacher still has.

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