epoxy resin and millilitres ?? MATHS? Engineers?

[steptoe]

I am about to fibreglass up a little windscreen rust.

the epoxy resin came in a 250ml tin *polyester resin LSE
the hardener is in a 10ml bottle * polyester catalyst 23mm dia x 26mm high of fluid

mix ratio is 10ml to the litre. I want to do 50ml resin at a time.

25% of this 10ml bottle of hardener will do the full tin, so I need to measure out 5% of this 10ml bottle , half a millilitre.

PICTURE THIS. with water one millilitre weighs one gram and volume is one centimetre cube, bit like air. so a ml = a cc ? right ? 1000cc = 1 litre = 1000ml , right ?

I am wondering how many drops of hardener to my 50mls resin.

IT GETS WORSE

In front of me is a 50ml measure out of my Gatorade powder keg. Same volume as a medicine measure cup. It measures 46mm dia by 26mm high. I CANNOT IMAGINE THAT IT WILL CONTAIN 50 WHITE CUISENAIRE RODS (1cm x 1cm x 1cm)

any engineers, maths bods, school teachers able to clear up my mind fog...please?

I can however see that one 50ml measure will fit in the 250ml tin 5 times and that 5 times the 10ml will go in the 50ml measure. It is the 50ml = 50 cubic centimeters I cannot visualise or fathom. Got the scale wrong ? Out comes the plasticine

26mm high divide by 4 for full tin = 6.5mml high, then divide that 6.5mm fluid high in bottle by 5. Every 1.3mm in hieght of fluid (catalyst per 50ml resin. SORTED !!

thanks !

[BaronVonChickenPants]

I've seen small syringes that have markings of 1/10th of a millilitre, I'd say something like that is probably your best bet.

Jordan.

[steptoe]

Hmm, needle exchange program somewhere ? Good thinking Jordan. Good to see you are all hooked up again. I think I wil mark the catalyst bottle and drop, drop, drop, 'til the mark

[Fury]

In front of me is a 50ml measure out of my Gatorade powder keg. Same volume as a medicine measure cup. It measures about 40mm dia by 20mm high. I CANNOT IMAGINE THAT IT WILL CONTAIN 50 WHITE CUISENAIRE RODS (1cm x 1cm x 1cm)

Your talking cc ( cubic Centremetre) here, not ml.

10 ml is a standard teaspoon.

Are you sure you are using epoxy ? - they are normally a ratio of 2:1, 3:1 or 4:1 ie: 40 ml part A to 10ml part B

Sounds like Polyester or Vynalester at around 100:1 or 1000ml to 10ml.
25% of your hardner should do the 250ml tin.

epoxy is more critical of exact amounts, but if polyester, just use

you are using 20% of the tin at a time - so...

measure out - in a seperate small container - about 25% of your hardener - by counting the drops.

say its 50 drops... then devide by 20% = 10 drops

If its polyester, I would estiimate around 6 to 7 drops per 50 ml resin.

clear as mud?:rolleyes:

[BaronVonChickenPants]

Usually pet supply stores have a selection of various sized syringes, I'm pretty sure the one I was thinking of came with Tom's baby panadol.

And yeah it's good to be back, even if it is just on dail up for the moment.

Jordan.

[steptoe]

Yeah, Fury, it is the 100:1 polyester resin- got it from a fibreglass supply shop.

I can work out the proportions of resin - hardener but, still tricked on this measure millilitre, cubic centimetre. A millilitre is 1/1000 of a litre, so too a cubic centimetre ? like an 1800 cc engine expressed as a 1.8 litre engine ??

[steptoe]

Volume

The standard unit of volume in the metric system is the litre. One litre is equal to 1000 cubic centimetres in volume. Other units of volume and their equivalents in litres are as follows:
1 millilitre = 0.001 litre
1 centilitre = 0.01 litre
1 decilitre = 0.1 litre
1 kilolitre = 1000 litres

From these units, we see that 1000 millilitres equal 1 litre; so 1 millilitre equals 1 cubic centimetre in volume. We abbreviate these volumes as follows:
1 millilitre = 1 ml
1 centilitre = 1 cl
1 decilitre = 1 dl
1 litre = 1 l
1 kilolitre = 1 kl

For reference, 1 litre is a little more than 1 quart. One teaspoon equals about 5 millilitres.

OK, so I knew that,but things do not gel sometimes, like visualising that 3 cc of super glue fits in those tiny 3ml tubes ?

I just have believe it and accept it

pinched the above from the web by copy and paste

[last celtic warrior]

Ok, I can't NOT say anything at this point...

CCs (cubic centimetres) are volumetrically equal to millilitres, it's simply different ways of describing the same amount of space, relevant to the situation you're working with. 1cc = 1ml = 1gr (if it's pure water). Metric all tallies up...

And make sure you never confuse polyester resin with epoxy resin. There is no such thing as epoxy polyester resin. That would work about as well as oil based watercolour paint...

I'm not trying to have a go at people or hurt anyones feelings here. I'm just edjumucating anyone that needs to know to save unnecessary confusion, as I think some of us already live with enough confustication...

(Had to add this, sorry) If your windscreen has rust, you have serious impurities in that there glass mate. As for the windscreen frame, how big are the holes you're 'glassing up? If they're just a couple that you could almost poke your finger through (once descaled and cleaned up) then you're fine bogging them. If it's any worse than that (and most older Subies are, nomatter how much the owners try not to think about it) then the only solution is to pop the screen out, cut a nice big piece out in order to remove any rusty bits, then form and seam-weld new .9mm sheet steel in. The windscreen frame is a major structural part of most cars, and any damage or missing bits allow the whole thing to collapse in on you during an accident.

[julian]

Most chemist shops will sell you syringes in a multitude of sizes from 0.5 mL to 10mL, but might look twice if you ask for needles. Most of those catalysts are pretty toxic chemicals so watch your skin and eyes when playing with small volume syringes; they can squirt suprising distances!

[steptoe]

OK guys, some good advice and info. yep, my error, in ignorance, it is polyester resin. And for future reference i found about twenty drops of catalyst does my gatorade 50ml measure just fine. I worked this out by trial and error - error being about 50 drops ! The holes vary in size from pin hole to about 20mm long . Very clever of Subaru not to let holes in the windscreen gutter drip into the drain below, instead of inside. It gets inside when it drops onto the air intake on each side though. What a mess i made of it too. Previous repair WAS bog. Repair is more for convenience than logevity given my initial intentions for this beast to be a donor - until I ran the arctic refrigeration system - its got gas and its C O L D !! Donation make take place after summer...

[Fury]

As far as longevity is concerned, If it were done with epoxy on bare , unpainted metal - especially if used with carbon fibre tape, is just as strong as sheet metal and will bond with the steel.
Polyester is only a temp fix and will crack out like bog ( which is usually polyester based)

Blank holes can be formed up with tape and cardboad - but once glassed with epoxy and carbon or kevlar, is actually nearly as strong - (and sometimes depennding on the laminate) stronger than the original steel

Thats why racing yachts, that used to be built from alloy, are now carbon composite epoxy - and it is far lighter. ( as well as being far more expensive !!)

by the way, I think you will find that 20 drops is way to much in temps above 17 degrees. It will set too fast and shrink. in Summer , ( just for referance purposes) try less than 10 drops per 50 ml.

a good test is if there is a bit in the bottom of the container, and it starts to get warm, there's too much catalyst ( hardiner) MEKP - or Methol Ethol Keytone Peroxide, actually changes the molecular structure of the resin. If there is too much saturation, it not only over stimulates the structure, it weakens it. It then shrinks and distorts the laminar layer and wont hold to the substrate it is being bonded to.

...however, Epoxy is not a molecular change, rather it completes a 2 part molecule which once complete any extra is just unused and doesn't get "watered down". extra just usually means its a bit sticky on the surface.

[last celtic warrior]

As long as you're safe in that car mate, that's all I'm worried about. By the way, I have the dies to form the outer lower corner sections of the screen frame for the MY Subie, so it's now easy to get the replacement piece, trim off what you don't need and weld it in. That way, you have the original profile in one piece of steel with full strength in the event of a collision.

As for carbon fibre being acceptably strong? Nope. Perfectly fine for in the middle of panels and the like, but a big no-no for structural framing on cars. The repair works fine, and would hold up better than steel if you belted it with a hammer, but in an accident, you need all framing areas to be able to bend out of shape and still have most of their original integrity. Carbon fibre/fibreglass/kevlar are not suitable for "impact absorbtion" areas (crumple zones). Even on aluminium vehicles, the framing is still steel, as steel will tear less than most other materials when you reef them about violently.

Anyway, if anyone needs the rust repair panel for the windscreen frame on their Subie, let me know...

[cooloothin]

reading through the small amount of maths in this thread had me thinking 'ow my head' but it sounds like you've almost got things sorted jono.

You're right in that it is often hard to fathom where chunky square visualised centimetre cubes fit in some containers, but has everyone forgotten pi R squared ?

Your 10ml bottle comes in at 10.8 cm2 with those measurements which is about right, given that your measurements are probably of the outside of the bottle, and the volume of plastic reduces the volume of free space inside.

Your gatorade 50ml cup though, with the measurements you gave is only 43.2 ml or same cm2... minus measuring error makes it even smaller, so it's no wonder you thought it looked odd. No matter how befuzzled one is, you can usually tell that something's not quite right. So unless your millimetres are out, gatorade is lying

[steptoe]

i measured the cup a while back as roughly 50ml - good for two stroke mixes