How much resin to use

[mastercraft98]

Hello. I was wondering how do you figure out how much resin you need to use for your csm or 1708 and other fiberglass cloth.I see that it comes in different .oz like 1.5oz or 6oz and the like. I either mix the poly :facepalm: to cold and it takes for ever to cure, or its to hot and by the time i get it to my projects it's already getting hard. I like like using epoxy just because if I didn't mix enough up I can go and mix up some more and continue on. with poly i either mix to much or not enough, and like I said if I don't mix enough up the first time it's to late for me cause the stuff I put down is starting to gel.

 

[Woodonglass]

Re: How much resin to use

Yeah, there is a learning curve. This will help some
http://www.fiberglasssite.com/servlet/the-68/Fiberglass-Information,-and-How/Detail

When mixing the resin with the hardener it should stay close to 1.5% to 2% Hardener to Volume of Resin. Calculator will tell you the ozs of each you need. If you stay in those ranges you should have about a 15 - 20 minute window to get the resin smoothed out. 5 mins of mixing and 15 mins of spreading.

 

[Decker83]

Re: How much resin to use

When you are mixing the poly you need to measure out how much poly each time and the right amount of hardner.
Just as WOG ^^^^^^ said.

I have found if you try to mix more than a quart of poly at a time it will start to kick to fast in the bucket. When you start to spread the poly out it will slow down the kick time because it dosn't get as hot. If you are going to need more than a quart at a time have more than one bucket measured out with the poly and the right amount of hardner ready. When you need the next quart just put in the hardner and mix well and keep going.
If your poly is just starting to kick you can still use the new mix to work back into it.
I use a injection needle like you use for injecting meat to measure my hardner and the buckets the HD sales to measure my poly.
After I measure it all out I pour the poly into large plastic coffee cans to mix and use the poly. I can reuse the coffee cans several times before I have to throw them away and I don't have to replace the expensive ones from HD as often.
Hope some of this helps you.
Keep up the work and you will get better at it.

 

[mastercraft98]

Re: How much resin to use

Thanks for the help.

 

[Yacht Dr.]

Re: How much resin to use

Hello. I was wondering how do you figure out how much resin you need to use for your csm or 1708 and other fiberglass cloth.I see that it comes in different .oz like 1.5oz or 6oz and the like. I either mix the poly :facepalm: to cold and it takes for ever to cure, or its to hot and by the time i get it to my projects it's already getting hard.

Your cat % rate is somewhere in between then. Not all Resins are the same. Some resin mixes will start to cure in a blink of an eye .. where as others will give you a 'warning' when it starts to kick off.

When mixing the resin with the hardener it should stay close to 1.5% to 2% Hardener to Volume of Resin. Calculator will tell you the ozs of each you need. If you stay in those ranges you should have about a 15 - 20 minute window to get the resin smoothed out. 5 mins of mixing and 15 mins of spreading.

5 mins of mixing is WAY too much with poly and mekp ..

If your poly is just starting to kick you can still use the new mix to work back into it.

Just to make sure we all understand .. you should not combine newly catted resin into 'kicking' resin. It will not dilute and give you more time. It will affect your cure time on the new mixed resin.

Get good quality poly resin and that should take care of most problems.

YD.

 

[zymox]

Re: How much resin to use

As Yacht Dr. stated: all resins isn't the same. I used to work for a company that fabricated polyester and we "pre" accelerated and "pre" decelerated the geltime depending on what the costumer needed. Most often the geltime was set @ 20 degree Celsius but sometimes at 23. The same poly could vary from 20 minutes to an hour at 20 C with 2% of hardener just because of how it was intended to be used, guns or by hand. The temp makes a hugh difference.

The one I uses now for ex. is specified to a geltime of 45 minutes @ 20C with 2% hardener. A couple of degrees lower will slow it down to a geltime of approx. 60 minutes and if I go higher on the temp. it will harden a lot faster.

Ask your dealer what the gel-time/pot-life time is for your resin and in what conditions then you have a good start if taken all of the above statements into consideration also

 

[oops!]

Re: How much resin to use

one of the the neat tricks, is to use the metric system.

it is far esaier than the imperial system.....you dont need to use a slide rule and calculator to determine 2 % as all the measurements are done by 10.

 

[zymox]

Re: How much resin to use

one of the the neat tricks, is to use the metric system.

it is far esaier than the imperial system.....you dont need to use a slide rule and calculator to determine 2 % as all the measurements are done by 10.

Oops! is absolutely true about this, it's much easier in all aspects

I use a scale for my 2%. 1 kg (1000g) of resins equals 20 gram of hardener. It works every time if I keep the temp right

This is how the test for the gel-time is done in the factory, by weight. I saw someone stated somewhere that the 2% is per volume but we never did it that way. A sample of 100grams resins plus 2grams of hardener is pored in a small can that is hold to temperature by a 20/23 degree C water bath. Then a thermometer is used to blend the two components and when stirring you check the temp at all the time. To cold you lift the can out of the water and to hot you keep it in there. A timer is started on the gel machine as soon as the sample guy starts to stir. Then when satisfied with the blending we put down a measure plate that hangs in two very thin copper wires down into the mix and starts the rotation of the sample plate on the geltime-machine, when it starts to gel the two copper wires do connect to each other and the clock stops giving you the geltime.

I can't remember the exact chemicals for the acc - dec stuff I talked about earlier but the working name for this products at DSM Resins where I used to work are Hobilon M and Hobilon Q. It's just different chemicals diluted in styrene. And suddenly I remember the two polyesters I was talking about also. The name for them was Synolite 528-0-2 that hardened in 20 minutes and Synolite 528-0-6 that hardened in an hour. Same stuff but different specifications and the only differences was the amount of Hobilon.
(The specific products are not manufactured anymore so I can talk about them.)

 

[mastercraft98]

Re: How much resin to use

Thanks for the info everyone. Decker83, never thought about getting several batches ready to go thanks. Sounds like I should order enough resin to do a job so that I don't get different part lots mixed together. Can anyone suggest a brand of resin or place to get it from? Thanks.

 

[oops!]

Re: How much resin to use

iboats is a great place to buy by the gallon.....

uscomp is a standard as well.

i buy from a local shop....look in the phone book under plastics

 

[Woodonglass]

Re: How much resin to use

I think Decker meant that once the resin is layed down and it starts to Kick new resin can be applied over the top of it Not that you can add resin to kicking resin in the pot. And I agree that mixing 5 mins with poly is too long. I get mixed up sometimes since I use Epoxy frequently. 15 - 30 seconds of mixing with poly should get the job done.

 

[Decker83]

Re: How much resin to use

Thanks WOG.
That is exactly what I was trying to say.

 

[oops!]

Re: How much resin to use

getting back to the resin starting to gell when you are glassing.....

you have to be really fast when glassing.......this is not a job that can be done slowly.

if you dont feel like an octopus during a glassing job, your going to slow.

i make larger batches, if there is waste,,,,there is waste.

one of the tricks,,,,if on a flat surface,,,dump some resin on and take a bondo spreader to move the stuff around.

once inital saturation is made, you can use your resin roller to move out the air.

during the hull extension, i regularly had to do very large layups. i needed to find a way to fully saturate 1708 that was three times the size of a transom in less than 15 minits by myself

 

[Woodonglass]

Re: How much resin to use

This^^^ is true but...Most of the guys on here are not dealing with a surface area quite as large as you were dealing with and the need for that large of a batch of mixed resin, IMHO is not the way to go especially in the early going. Most of the new-b's don't have a clue how much resin will wet out how much glass. Until they "Get that clue" they should mix small batches and do small batches until they start to "get it" Then they can tackle larger and larger areas and more resin. Waste will occur but there are methods to keep it minimal. I like to use a bondo spreader as well, but when I mentioned it to Friscoboater he did not like using it. To each his own. But the for multiple layers is to try and get them done before the previous one cures so the chemical bond can occur, at least that's what the good Dr. OOPS always says!!!

 

[zymox]

Re: How much resin to use

I have given this a great deal of "mind" time and it can be that I'm way out of line here but I would love to know how it works for real.

Note: All in this reply of mine is only my own thought and is not to be used as a fact.

I think most 1:st timers don't think about that it will start to cure way faster in the bucket than on the layup. At least I didn't the first time. :facepalm: I really can't explain why it's like this especially since most of my stuff is in the same room and thereby should be at the same temp. I only imagine that it has to do with the evaporation in a thin layer and the cooling factor of that. This evaporation will not happen in the bucket. Also when a bucket of resins kicks in it goes very fast due to the exothermic heat, build up by the reaction. Especially if you have a lot of resins in it not being able to cool as much as a thin layer.

I gave Oops! chemical bonding a good thought and he is absolutely right about it.
My thoughts is like this, I hope you correct me if I'm wrong here

Polyester when it hardens out forms a long sets of molecule-chains that binds to each other link by link so to speak. If it gets the chance to cure to the fullest you will have a set of molecule-chains (your laminate) that is not very easy to break up again and it doesn't help if you do a wet layer on top of it. Some will bind anyway since the world ain't perfect and make it stick to the old layer but your laminate will not be very solid. Since you can't break down the chains easily you can't get many new links to connect and be part of that original chain. We might be able to dissolve some of it by enlarging the area by grinding and trying to clean and at the same time dissolve some more of the most upper part of that molecule chain using acetone. Making a better bond than if we didn't use acetone.

If you on the other hand uses what Oops! always states, the chain ain't closed (cured) and has not stopped its growth. This will make the molecule-chains to grow into the next layup like it all was one single layup.

This makes sense to me for all chemicals that bonds and why wax and pva is used as releasing agents. It's the same with paint, glue or what ever. Wet in wet and you get a really good bond between the layers. If it's fully cured then you should sand it first to make the surface larger and also clean it well to get all dust off and in the same time dissolve some of the closed chains. If it then takes several days for it to cure a 100% as if you have a lower temp then you perhaps just have to continue without taking any prep. actions.