Model Boat Mayhem
Mess Deck: General Section => Beginners start here...! => Topic started by: AlanP on August 07, 2008, 08:46:41 pm
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Thought I would resin the hull of my new springer.
Read instructions very carefully as I have heard that the mixing is crucial, got a credit type spreader as against a brush (recommended by boatmadman) measured resin and hardener very carefully and started to mix them, mmmm better put my welding gloves on, ooops I now have something that resembles a lollipop on the end of my mixing stick and its extremely hot. ::)
Second attempt, same amount of resin, half the hardener, thats better, someone who shall be nameless (boatmadman) forgot to tell me how runny the stuff is, everything in the workshop is now stuck with glass resin including the springer hull to the bench, had to unlace my shoes to get back to the house. :embarrassed:
So now to the question, well there had to be one, on trying to sand the hull the sandpaper just keeps getting clogged up, does it need leaving longer or is there something that I can wipe it with to get rid of the stickiness
Shoeless Alan :(
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Alan
Messy stuff innit ;D
You need to let it harden for a few days before sanding down, and it will help with lots of fresh air - outside if possible.
Then, use wet/dry with plenty water and a drop of washing up liquid. I start with 260 grit and work up to 400 or 600 before painting.
Ian
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Hi Alan
Exactly the same thing happened to me, 10ml of resin and 2 - 3 cm of hardener, mixed it in a spray lid and whoosh, it bubbled got hot and set like stone within seconds!
I think the instructions for the hardener are a guide only. ;D
I think the stickiness is due to little hardener, this happened in my case, you have to leave it a while like Ian says.
regards
Gary :)
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Are you really sure you have got the proportions right? 10ml resin to 2-3 cm of hardener sounds way too much hardener. If I was filling up a spray can top I'd only be considering 0.5cm or so of hardener. If using Fastglass resin you need less than 2% hardener by volume.
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Hi Colin
I'm using David's 'Fastglas,' on the back of the tin it says use 2 - 3 cm of hardener to each 10ml of resin.
I read it 3 times to make sure - perhaps they missed a nought of the 10ml?
regards
Gary :)
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Definately missing a zero,
I have become a bit blase` when mixing polyester resin i just vary the size of the squirt of hardener to suit the amount of resin, but then i've used around 80 litres on models and my race care build over 20 yrs.
Before anyone jumps to poo poo my techniques let me say i never had a situation of exess heat/cracking etc a few sticky ones though, and for pots of 500ml or more i use a medice measure cup.
For mixing resins or paints i have a 300mm prop shafe with Graupner x40 prop, used in my cordless drill it mixes rapidly.
A word of caution in the thicker resin it does create air bubbles which if not rolled or brushed well will leave pin holes in the surface.
Great fun experimenting though.
Damien.
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Is this 'David's Fastglass' (used to be David's Isopon?) the stuff you buy from Halfords? I was in the branch in Northwich last weekend looking to buy some for a job I need to do on our house.
Reading the instructions, I was somewhat taken aback by the amount of hardener required. According to the instructions, you would need many tubes of hardener for the 500ml screw top can that I was about to buy.
I remember thinking to myself "That can't be right" and left it on the shelf. A missing zero would explain everything.
Malc
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Yes Malcom, I bought it from Halfords, Northfield. Birmingham.
Gary
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Ah " a missing zero", yes that would explain my mess-up too! >:(
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well I have used lots of halfords fastglass, using 2.5cm to 10ml resin and it has always worked for me. Goes off in about 10 to 15mins.
Ian
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considering that 10 ml is only two teaspoonful 2.5cm of hardener does seems a tad excessive ???
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hi there all
The small tins of resin which you purchase from the Auto shops, such as David's resins, there are 2 things which we must consider and be aware of, when using them.
The environment you are going to use it - either in/outside - and also how long the tin has been stood on the shop shelf.
First of all, all of the resins we use in our hobby are called Pre-accellerated resins - meaning there is an accellerator blended into the resin on manufacture. This is the actual agent which hardens the resin. The haradener or catalist is the 2nd part to this match. When the resin has been standing for a certain length of time, the mixes in the resin start to settle to the bottom of the tin. So, when we come to using them, if we have not shaken the resin up for at least a good 20 mins I MEAN A GOOD 20 MINUTES the chances are you are not using the correct mixture of resin. Sometimes, you will find, as you work down the tin without shaking it; the resin mix that we have either goes off extremely quickly or doesnt go off at all.
The 2nd thing to consider is when we are using Davids resins they are produced for the DIY market where the person who is more likely to be working in a cold garage/outside environment. So, to aid curing or the resin hardening, they advise a larger/maximum amount of hardener mix. Now, if we are working in an environment which is indoors at a temperature of between 20-26 degrees C - we must begin to start to reduce the hardener mix.
Sometimes, when we mix too much hardener in, this can also create a situation where the resin stays tacky for a long time - as well as having the other way - where we havent mixed enough hardener in.
Under normal working conditions and correct hardener/resin mix; you should get at least 20 minutes working time out of the resin - regardless of the amount you mix. Obviously the larger/shallower tray/dish you mix your resin in - a slightly longer working time you will have.
Hope this is of some help.
aye
john e
bluebird
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Your off to a grand start.
I tried my first fiberglassing back in high school
No one told me there was supposed to be "glass", and
No one told me there was a hardener catalyst...
The model was great, but it was sticky for at least a year.
{-)
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Well that woke a few of you up {-) The stickiness seems to have almost gone after a few days in the fresh air and I have just about cleared the mess up. The sanding will start as soon as I can find some rubber gloves for the wife, shouldn't take her too long ;)
Good info there John, didnt know that the resin settled, but 20 mins shaking thats worse than sanding {-)
Alan
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hi there one and all
There used to be a Company, which was based just near Liverpool - they used to deal with re-graded resin.
This is the resin which had basically gone past its sell-by date - and what they used to do is aggitate them for 4/5 days and then reblend them (in other words they used to mix all the resins up in a big vat) and then they sold it as a 'low grade' resin - it did not quite come up to Lloyds' standards.
Lloyds standards resins come in various categories - the stuff we used to use for the life boats & the life raft containers was Grade A+ well, it has to be fire retardent - the gell is and also so is the resin.
Some of this resin was a greenish colour (queer colour) until you added the pigments i.e. white for the containers and orange for the lifeboats.
All clever stuff.
aye
john e
bluebird
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I reckon the proportions are the wrong way round 10 ml of hardener to 2-3 cm of resin, If using a poly cup or margarine container.
Nick
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Hy Guys
If you find that the fibreglass is still a bit sticky after a few days, give the item / hull a good sprinkling of talcum powder, rub it all over and that should sort it out.
Cheers
Bosun
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No, it is definately 10ml resin to 2-3 cm hardener - I have used it a lot with no problem - just do as it says on the tin.
Ian
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Aha I see, it's paste hardener, 2-3 cm squeezed out of tube. :) I'm used to MEKP hardener/catalyst, its a clear liquid and is used at 1-4 % by volume, usually 1-2% in our lovely Queensland weather ;)
Regards
Nick