Need some help with resin problems

Signed-In Members Don't See This Ad

JustLookin'

Member
Joined
Jun 3, 2019
Messages
13
Location
Australia
Please forgive any stupid questions, I am sill really new to casting and am having an issue with the resin I am using.
I was recommended to use Bio Casting Epoxy Resin for my pen blanks, and not really knowing anything about resins, I bought it and have cast a few blanks.
It was advised that since it is winter here in AU, that it would take longer to fully cure than the 7 day recommendation on the packaging, so I have left them to sit for 2 weeks now.
We are TBC without bushings, and while trying to turn one of our made blanks today, it started to catch and the lathe would stop turning, so we would tighten the lathe which then splayed the end on the blanks.
I have no idea why this is happening, whether the blanks are not cured enough or whether the resin is not the correct type, so any information or guidance you can give me would be appreciated.

If this is not the right resin to use, could you advise which would be best. We do not have pressure pots, and I really would prefer an odourless resin if possible
 
Signed-In Members Don't See This Ad

randyrls

Member
Joined
Feb 2, 2006
Messages
4,120
Location
Harrisburg, PA 17112
Lynne; If you are just turning between centers with some kind of a point, you will have problems. Bushings press against the other bushing, but points press outward and expand the ends of the blank and may cause the blank to crack. If the blank starts out square, you may want to power sand the corners round. This can help, but this just isn't a good way to go. Finishing can be done this way because the force on the blank is low.

I know some on this site do it this way, but I've never had much success with this.

With care you can make your own bushings from acrylic or solid surface counter material.

We are TBC without bushings, and while trying to turn one of our made blanks today, it started to catch and the lathe would stop turning, so we would tighten the lathe which then splayed the end on the blanks.
 

robutacion

Member
Joined
Aug 6, 2009
Messages
5,988
Location
Australia - SA Adelaide Hills
Please forgive any stupid questions, I am sill really new to casting and am having an issue with the resin I am using.
I was recommended to use Bio Casting Epoxy Resin for my pen blanks, and not really knowing anything about resins, I bought it and have cast a few blanks.
It was advised that since it is winter here in AU, that it would take longer to fully cure than the 7 day recommendation on the packaging, so I have left them to sit for 2 weeks now.
We are TBC without bushings, and while trying to turn one of our made blanks today, it started to catch and the lathe would stop turning, so we would tighten the lathe which then splayed the end on the blanks.
I have no idea why this is happening, whether the blanks are not cured enough or whether the resin is not the correct type, so any information or guidance you can give me would be appreciated.

If this is not the right resin to use, could you advise which would be best. We do not have pressure pots, and I really would prefer an odourless resin if possible
G'day Lynne,

You don't need to apologise for asking questions and stupid questions are those never answered...!

I use that Resin so could you elaborate if you are using the fast or slow dry one..?

Some epoxy resins are very weather/temps sensitive and these Bio resins are the worse so, the decision to use a fast setting resin that can be worked on in about 48 hours the slow setting resin will take well over 7 days before it can be worked on.

In my experience working with these resins, they do a great job at casting, I always use the fast set resin it gives you over 1 1/2 hours of working time in Winter and in Summer you still have about 20 minutes which is plenty, however, I have found that molds put in the pressure pot at 80 PSI pressure are completely set in 24 hours with temps about 20 to 25C in colder days as we have been having plenty of those, I put one of those fan forced small heaters about 2' from the pressure pots and that assures that the resin is set and hard when the pot lid is open, however, any molds or small leftovers that didn't fit in my 2 pressure pots, when I take the set molds out of the pots those containers with the exact same resin mix are still soft to very soft, this is the case in Winter and temps below 20C

So, you are using a good resin and damn expensive as hell, if the mix of 2 to 1 is not perfect/accurate it will cause lots of problems, it will never set faster than it should but the contrary is the case, I had experiments reversing the amounts of resin and hardener normally 2 to 1 but I used 2 parts hardener and 1 part resin, this was about 4 months ago and the mix did never set/got hard even putting it in the hot sun, it just doesn't harden but I have also experimented with 1 1/2 parts of resin and 1 part of hardener, that reduced amount of resin did affect the mix that took a good 14 days before it hardened enough to be worked on.

Another negative of these resins is that heat will make the hard/set resin to become soft and therefore deform easily so, friction from spinning on turning in between centres generates sufficient heat to soften the blank ends and therefore deform or squeeze them.

So, after the blanks were cast and you can tell that they are hard do not turn them as they are not cured, the complete cure happens between 7 to 14 days depending on the temps, only then the resin is hardened through and slightly less prone to be affected from small amounts of heat when turning.

My first suggestion to you is, get a pressure pot and make sure if you mix wood in the resin that the wood is bone dry and lastly, give as much time as you can before you turn freshly cast blanks.

Hope this helps,

PS: I don't know where you are in Australia but if you are within driving distance from Mount Compass in SA, stop by and I will take you through a few tricks...!

Cheers
George
 

jttheclockman

Member
Joined
Feb 22, 2005
Messages
12,276
Location
NJ, USA.
Wow this is a very good reply from George. Someone that has actually used that resin and has experienced the ins and outs of the different types. I am impressed and that should answer all of the OP questions. Good job. 🏆

The one point that scares me just a tad is the 80 lbs of air pressure. That is quite high and would not recommend this is if using pots such as those from Harbor Freight or whatever they call them over there. Make sure the pot is a good quality. If using those foam molds they may not withstand that kind of pressure either. One other thing when heat is applied to a pressure tank it can raise the pressure inside. With resins I believe you do not need such high pressure with any of them but I do not know that resin. This is just a side thought on a very well presented answer to the OP by George.
 
Last edited:

robutacion

Member
Joined
Aug 6, 2009
Messages
5,988
Location
Australia - SA Adelaide Hills
Wow this is a very good reply from George. Someone that has actually used that resin and has experienced the ins and outs of the different types. I am impressed and that should answer all of the OP questions. Good job. 🏆

The one point that scares me just a tad is the 80 lbs of air pressure. That is quite high and would not recommend this is if using pots such as those from Harbor Freight or whatever they call them over there. Make sure the pot is a good quality. If using those foam molds they may not withstand that kind of pressure either. One other thing when heat is applied to a pressure tank it can raise the pressure inside. With resins I believe you do not need such high pressure with any of them but I do not know that resin. This is just a side thought on a very well presented answer to the OP by George.
Thank you John,

I can elaborate a bit on your concerns and in a way your observations are important and relevant as we sometimes forget that not everybody has the same knowledge and experiences, therefore, I'm glad you brought those issues up so that I can discuss them a little further.

Yes, not all pressure pots are rated to 80PSI on even higher, most of the more economical pots are rated from 40 to 60PSI so that is important to note so that you are not using any higher pressures than what is "safe" for that particular pot. This brings 2 issues and those are what type castings are you considering to do and what type of pot you require. What I mean is, if you are only going to cast acrylic blanks, any 40 PSI pressure is more than sufficient but, if you intend to cast woods with lots of holes, crevasses, cracks, or something like Banksia pods and many other types of seeds/pods/materials you do require sufficient pressure to ensure the resin is forced into all those small crevasses, you then need as much pressure as possible the more the better so 80PSI is not excessive if you make sure your post is rated to those pressures, manufacturers give you the "recommended" max pressure but they have at least a 20% of safety margin to what those pots can withstand, mine are rated to 100PSI and I often use those pressures but I try not to mention that too often so that less inform folks do not attempt is based on the fact that I do it, that is not what I would expect but we all make mistakes, right...?

I have to stress the fact that you need to know the max rated pressure of your pot and as I said, purchased the right type of pot for the type of casting you intend to do. It is also a fact that is not the first time a pressure pot blows, mainly its lid, there have been close calls to injury so playing it "safe" is a good idea.

I never used foam molds so I can't tell you how they would perform in 80 or more PSI pressures, most folks make their molds out of the white kitchen board material which has a technical name I don't remember, that is mainly what I use, some plastic takeaway containers do also well.

Now, heat and pressure pots...! firstly I should make clear that putting a small fan forced heater a couple of feet from the pot(s) in those ice cold days/nights (below 10C) is the only way to get the resin to reach sufficient curing temperature inside the pot for an overnight up to 24 hours pot time. The temperature that these small fan forced heaters produce is not as high as some people may think, I can put my hand on the pot surface where the heater is blowing air/heat to and I can keep my hand in there without burning, remember that 2 feet distance on these small heaters the temperatures are reduced to half of the heater capacity to the surface is pointed at but at least the other half of the pot is exposed to those cold temperatures so the extra pressure the heat creates inside of the pressure pot is no more than 5PSI.

The question can be asked, what is the temperature inside the pot when the resin reaches its max exothermic temp or when the resin turns from liquid to a solid...? Well, I just looked everywhere for the pics I took from a test I made to obtain that exact information, I know that I have shown it in here but was mixed with some other thread either mine or someone else's, I can't find it nor the pics I took of that experiment but someone here may have a better memory and remember where that info is and confirm what I remember and that is, the max temperature reached inside the pot during the resin setting/hardening was about 60°C, the pot surface was about the same, the temps dropped quite quickly after that with the pot outside surface reaching the ambient temp fairly fast. An identical result was obtained when the heater was on in low weather temps, the exothermic reaction did happen when the air inside the pot reached the 60°C, the pot outer pot surfaces exposed to the heater showed about 65°C for a short period of time reducing fairly fast to 60C and then reducing about 10C's for the next 2 hours from where it kept the average heat exposed pot surface to about 35°C for the rest of the time the heater was on, when the pot was opened the blanks were solid and set, ready for work (demold, slice, sand, etc...!).

With all this said, REMEMBER that I didn't mention the surface temperature of the resin when reaches its mac exothermic temps, I could give you some numbers but I prefer to tell you, don't even think in touching it, it burns as bad as the burns from hot-glue guns, how do I know...? have a guess...!:mad:

I hope this gives you and others a bit more light on the issue...!

Cheers
George;)
 

JustLookin'

Member
Joined
Jun 3, 2019
Messages
13
Location
Australia
I use that Resin so could you elaborate if you are using the fast or slow dry one..?
Hi George, Thank you so much for replying. The information is very concise, and has helped me a lot, but I do have further questions, which I will list below.

First off, I am using the fast one. It was recommended to buy the slow one, but after reading the pot life and thickness you can use it, decided the hard was more appropriate to my needs.


In my experience working with these resins, they do a great job at casting, I always use the fast set resin it gives you over 1 1/2 hours of working time in Winter and in Summer you still have about 20 minutes which is plenty,
First question. When wanting to mix several colours, I have left the resin sit for up to 40 minutes, waiting for it to "gel" so it won't mix together. Is this long enough, or should I leave it longer on these cooler days? I did my last casting on Tuesday when we had that lovely warm weather here in Adelaide, but I have a feeling it has mixed together. Not demolded yet, so won't know for sure until I do that.
I'm not really sure how thick the resin needs to be to stop it from mixing together.

I also wonder if there is a minimum amount that should be mixed. We are using PVC pipe to mold into at the moment. Each holds 36ml of water, which equates to about 39ml of the mixed resin if I did my math right.
The first time we poured, we did tube by tube, so were mixing only enough for each tube at a time. This last pour (our second time), I mixed enough for 6 tubes.
I had a horrible time getting the first lot out of the pipes after leaving them for a week, so bought some mold release. Used it this time, but they still seem to be stuck fast in the tubes, so not sure what I've done wrong.


So, you are using a good resin and damn expensive as hell, if the mix of 2 to 1 is not perfect/accurate it will cause lots of problems, it will never set faster than it should but the contrary is the case, I had experiments reversing the amounts of resin and hardener normally 2 to 1 but I used 2 parts hardener and 1 part resin, this was about 4 months ago and the mix did never set/got hard even putting it in the hot sun, it just doesn't harden but I have also experimented with 1 1/2 parts of resin and 1 part of hardener, that reduced amount of resin did affect the mix that took a good 14 days before it hardened enough to be worked on.
I really like this resin. I love that it has no odour to it, so I can bring it inside where it is warmer than the workshop and not have it stink up the house, and I hear ya with the mixing more hardener having the opposite effect. I accidentally mixed too much hardener in a small amount of resin about 10 days ago and it is still like thick toffee in the bottom of the cup LOL

Another negative of these resins is that heat will make the hard/set resin to become soft and therefore deform easily so, friction from spinning on turning in between centres generates sufficient heat to soften the blank ends and therefore deform or squeeze them.

So, after the blanks were cast and you can tell that they are hard do not turn them as they are not cured, the complete cure happens between 7 to 14 days depending on the temps, only then the resin is hardened through and slightly less prone to be affected from small amounts of heat when turning.
That makes sense, but I had left this last blank for 14 days before turning, and it still splayed the ends. Mind you, we cast this lot of blanks in cooler weather without thinking, and left them in the workshop where it is much colder, so I am wondering if that something to do with it.

After talking with the guys at AMC, they suggested bringing the molds inside where we have heating, so this lot that's what I've done. So far so good, but we do turn the heating off over night. The house doesn't get as cold as the workshop, but it can get quite cool. Will the rise and fall of temperatures have an issue with the curing times?

How long do you suggest to leave the blanks before turning, and how do you know when they are fully cured?
Would using bushings on the ends help with the splaying, and if so, what type should I get, or is there information on how to make them somewhere?


My first suggestion to you is, get a pressure pot and make sure if you mix wood in the resin that the wood is bone dry and lastly, give as much time as you can before you turn freshly cast blanks.
How important is it to use a pressure pot? We won't be mixing wood with these, or anything else like that. We do want to use glitters though.
If we did get a pressure pot, would the one from SCA suffice?


PS: I don't know where you are in Australia but if you are within driving distance from Mount Compass in SA, stop by and I will take you through a few tricks...!
I'm in Virginia :) Your a little far for me to drop in, but maybe if we are ever down that way, we can arrange a meeting.

Thank you again SO much for your help. That's all I can think of for now :)
 

robutacion

Member
Joined
Aug 6, 2009
Messages
5,988
Location
Australia - SA Adelaide Hills
Ok, let's sort those issues.

The use/choice of the Fast set was the correct decision.

For creating multiple colours blanks with good separation in between colours, you are using the wrong resin, you would be much better served with the Polyester resin and put up with the nasty smell. These new Bio Epoxy resins are very difficult to get that "gelling" point we normally get with the Polyester resins, the bio-resins tend to go from very liquid to set in seconds, I have attempted multiple colours but I never had the separation I wanted, see below;

017.JPG

The only way you can have a better idea how long you need to wait before you make the multicolours pours is to get some of those long stainless steel prong oven/cooking thermometers, put one on each of the containers with each of the mixed colours as soon as you mix them and keep an eye to the temperature increase, the resin will maintain an unchanged temp for some time depending if winter or summer, as soon as the temperature starts to rise this means that the exothermic reaction is starting so is time to move fast and pour the colours and do any swirls or other effects as quickly as you can otherwise if it starts to smoke, you are too late.

This may be OK if you are only creating acrylic multicolour blanks but if you want to cast hybrids with wood or pods, this is no good because, by the time you put the molds in the pot, the resin is already too hard to allow the air pressure push the resin into any crevasses, you need your resin to be as liquid as possible to get a good resin penetration.

There are no specific sizes pours to get good results, I find the smaller pours and I mean small to be the most tricky ones to get right.

As for the mold release, they don't always work, I like to use the same product I was using when I was using Polyester resin and that is the blue PVA but I never used the pvc tubes, I know they are great to save resin, they work well with Polyester but I have my doubts that my PVA blue will allow the blanks to come out easy. There is one thing that I would suggest you try and that is, get your molds coated with the mold release and let it dry completely. With this colder temperatures use a small fan forced heater to help you with the process, keep the resin warm before the pour and after the pour is completed, keep the heater blowing hot air to the molds, if too hot put in on settings 2, you should be able to keep your hand next to the molds and not burning, just warm enough, try to make your pours later afternoon and let it set overnight with the low heat, turn the heater off in the morning and try to demold in the afternoon and lets us know what happened.

Some resins require 14 days to fully cure these Bio resins in the fast dry type does require 7 days for all the chemicals to fully cure, only because it feels hard when coming out of the mold does not mean the resin is cured so, having them for those 7 days in a place at 25°C, in winter inside the house he keep it about those temperatures so better than in the shed where is so much colder this time of the year, in summer things are a little easier and better for using these resins.

My opinion is that a pressure pot allows you to get better casts and no air bubbles, I have no idea what pressure pots can be found at SCA I don't know what this place is so if you let me know I can certainly tell you if is suitable or not.

Yes, Virginia is a little far but maybe one day you come my way and visit.

Hope this answers some of your questions, you're welcome to ask any questions you may have...!

Cheers
George
 

JustLookin'

Member
Joined
Jun 3, 2019
Messages
13
Location
Australia
Ok, let's sort those issues.

The use/choice of the Fast set was the correct decision.

For creating multiple colours blanks with good separation in between colours, you are using the wrong resin, you would be much better served with the Polyester resin and put up with the nasty smell. These new Bio Epoxy resins are very difficult to get that "gelling" point we normally get with the Polyester resins, the bio-resins tend to go from very liquid to set in seconds, I have attempted multiple colours but I never had the separation I wanted, see below;

View attachment 220745
These are very nice, even if not what you expected :)

The only way you can have a better idea how long you need to wait before you make the multicolours pours is to get some of those long stainless steel prong oven/cooking thermometers, put one on each of the containers with each of the mixed colours as soon as you mix them and keep an eye to the temperature increase, the resin will maintain an unchanged temp for some time depending if winter or summer, as soon as the temperature starts to rise this means that the exothermic reaction is starting so is time to move fast and pour the colours and do any swirls or other effects as quickly as you can otherwise if it starts to smoke, you are too late.
Had never thought of using a thermometer, or that it smoked. Have never seen it at that point. Will look at getting some of those and keeping an eye on it.

There are no specific sizes pours to get good results, I find the smaller pours and I mean small to be the most tricky ones to get right.
I did notice a huge difference when I mixed up enough for 6 molds as opposed to only one, and seeing as it has such a long pot life, it is quite easy to mix up enough for everything needed, pour into individual cups and mix colours as desired.

As for the mold release, they don't always work, I like to use the same product I was using when I was using Polyester resin and that is the blue PVA but I never used the pvc tubes, I know they are great to save resin, they work well with Polyester but I have my doubts that my PVA blue will allow the blanks to come out easy. There is one thing that I would suggest you try and that is, get your molds coated with the mold release and let it dry completely. With this colder temperatures use a small fan forced heater to help you with the process, keep the resin warm before the pour and after the pour is completed, keep the heater blowing hot air to the molds, if too hot put in on settings 2, you should be able to keep your hand next to the molds and not burning, just warm enough, try to make your pours later afternoon and let it set overnight with the low heat, turn the heater off in the morning and try to demold in the afternoon and lets us know what happened.
I will give this a try, although this lot I have waiting to demould was done in a similar way. I just have to get hubby to demould them for me. Perhaps I didn't spray enough of the release agent in the mold, or maybe I didn't let it dry properly before adding the resin?

Some resins require 14 days to fully cure these Bio resins in the fast dry type does require 7 days for all the chemicals to fully cure, only because it feels hard when coming out of the mold does not mean the resin is cured so, having them for those 7 days in a place at 25°C, in winter inside the house he keep it about those temperatures so better than in the shed where is so much colder this time of the year, in summer things are a little easier and better for using these resins.
Great, so hopefully these new ones will be right to go in about 5 days. I will update how they went when we try turning them

My opinion is that a pressure pot allows you to get better casts and no air bubbles, I have no idea what pressure pots can be found at SCA I don't know what this place is so if you let me know I can certainly tell you if is suitable or not.
SCA = Super Cheap Auto's. I have read a lot of people use this brand, and think there is a thread on this forum (could be wrong) on how to modify it to use it for this purpose.

To be honest, using a pressure pot scares me, and I'm not sure I'm ready for that step yet, and would not even know how to use it :)

Thank you again for such wonderful responses. You have been a fantastic help
 

robutacion

Member
Joined
Aug 6, 2009
Messages
5,988
Location
Australia - SA Adelaide Hills
The pressure pots you are referring to are good enough for what you will be using them for, not forgetting that to be able to run a pressure pot you need an air compressor it doesn't need to be a big one, any of the ones seen in stores will be OK.

Yes, some pots come already modified and ready to use, you have no reason to be scared of using a pressure pot at such low pressures and there is basically nothing to learn about the pots use, you simply put your molds in there, close the lid and add air pressure that both compressor and pot will have a pressure gauge to tell you how much pressure you got in, after that you remove the air hose and let the pot be for some hours, when ready to open the lid, you need to let the air out of the pot before undoing the wingscrews, remove the lid and admire what you have in the molds you poured previously so nothing too complicated about it, really...!

Cheers
George
 
Top Bottom