Infusion Q&A

Price wise no savings in my case, on the contrary, RI adds about 10% on building materials (in comparison with handlayup) but it also depends on laminate thickness. My lightweight multihull build has a very thin laminate thickness. The more laminate thickness the less relative resin usage.

 

That totally depends on a couple of factors, including the design of the object, the laminate thickness, the desired thickness of the laminate, etc.

Looking at high volume markets, like windmill blades and bridges, these are all infused, and for a reason. For them, and using their variables, it is cheaper.

For a thin laminate on a foam cored boat (outer skin) it might make more sense to do a hand laminate. For the inside infusion can make more sense, with thick laminates on places (keel area) and laminating inside in general is a mess. (human factor)

 

I just got my first taste of infusion last week and wow, i want to infuse something, so i have a few questions, we used shade cloth on top of the peel ply but as i am trying to find scources i was wondering what percentage fabric one would use.
1/ It seems to me that a fabric that blocks 30% of UV would be less dense than one that blocks 80% so would allow for faster resin flow,if this is so can anyone tell me what i should be buying, im going to have to order online as nobody has it locally so any scources would be appreciated, in fact any good scources for any of the consumables would be helpful.
2/ Any preferences on pumps? I currently have a Edwards but it is a bit small, maybe 2cfm and quit on me last time i used it so i think i want a new one around 6cfm, any advantage in going larger other than evacuating the bag quicker? (which is less of an advantage with infusion than bagging)
3/ What is the VE resin of choice with a nice long gel time?
4/ Would it be a good idea to hook up 2 pumps with ball valves so you could use both to evacuate then shut one off and have it as a standby should the other fail,seems prudent on a big job.
Thats about it for now i guess.

Steve.

 

i use 30% shade cloth because it wastes less resin than a heavier shade cloth will.

Opposite to what your intuition is telling you, a heavier shade cloth will actually infuse faster. The physics by which the mechanism works, is MOST affected by 3 things - resin viscosity, the permeability of the layup, and the driving force (vacuum pressure). Thicker shade cloths or flow media, provide higher permeability by holding a larger gap between the vacuum bag which is squeezing down onto the layup, and the layup itself. Its through this highly permeable gap that the resin flows quite quickly and allows the resin to be pulled a greater distance.

The CFM of the pump is not relevant other than to evacuate the bag quickly at the beginning before any resin is even mixed- you dont need a big CFM pump to infuse large pieces. Its the vacuum PRESSURE that is important, so you want a pump that will achieve a strong vacuum, upto near the solvent boiling pressure if your using a vinylester or polyester etc - the styrene will boil off if the vacuum is too strong. Most people use a rotary vane pump. Connect a needle valve inline with it so you can control the vacuum pressure.

Having a redundant pump is certainly a good idea if you can afford one. However i have only 1 decent quality pump and its never failed in over 10 years. Look after them and theyre very reliable.

With VE resins, theyres so many to choose from these days, my local has 15+ different vinyl esters... speak with your supplier about what suits your needs RE; mechanical properties, gel times etc

 

And of course use the VE that is locally available. I like infusing with Polynt VE370SC, but you will probably not be able to get it.

If you need to buy online, you could just as well buy infusion mesh instead of shade cloth. Buy one that has a speed that fits your laminate. Laminates that are more difficult to infuse (carbon for instance) need slower mesh.

On pumps: by far most pumps generate plenty of vacuum. What you would ultimately want is a vacuum of about 95% to 99,5% (50 mbar to 5 mbar). Preferably below 20 mbar, especially if you are in a humid area, or use hygroscopic materials (aramide and balsa for instance)
The low vacuum allows you to boil of water that might be present in your dry laminate. Too low, however, and you will boil off ingredients of the resin.
This said, I have been able to boil water in a degassing chamber, but I have not been able to boil off styrene. The structures and piping we use in the composite industry are always a bit leaky, so you will not reach a vacuum deep enough for that in general.
If your pump went bad on you, I would see if I could source a new one. Check on what you buy: the ultra-cheap pumps that are available everywhere spit oil unless they reach a very deep vacuum. Which means it will spit oil about always. (some types have disposable filters however).
The more industrial pumps have self-regenerating filters, which make the pumps suitable for a broader range of vacuum. (usually from 500 mbar to lower)

Here is an example of a cheap pump:
http://www.vacuumsystemen.com/losse-vacuumpompen/evd-ve-series/evd-ve115sv.html

And here of an industrial one:
http://www.vacuumsystemen.com/losse-vacuumpompen/ev-serie/ve-0010nm.html

 

thanks guys,i will compare prices of shade cloth vs infusion media. I would love to buy an industrial quality pump but too much $ for now, on the project i helped on recently we used a Robinair model#15600 pump which had already done all the parts for a 42ft cat and was still going strong and was more than adequate so i think my son and i will buy one each, they are less than $300 on Amazon with free shipping. I actually have a quality pump that i have never used because its 3 ph. its also overkill at 40cfm.

Steve.

 

iNFUSION RESIN

who in the usa sells a good polyester ot vinylester resin suitable for infusion?

 

Most industrial suppliers should have them. If not, you are talking to the wrong supplier. (probably a reseller of a small selection of materials)

 

Can you use VE up to the waterline and then PE thru the topsides in an infusion, are they chemically compatable for this to work?

Steve.

 

I would say its possible as the chemistries are compatible - you can use VE with PE gelcoats for example - the question is why would you want to make it complicated like this and not just use VE for everything as it has superior mechanical properties at a comparable cost?

 

The only complication would be that you would mix VE first and change to PE when the fronts reached a bit above the waterline, i think i could keep track of that. The reason to do this would be cost. For most situations poly is more than adequate, most boats in the world are built with it but it would be good to have the resistance to osmosis afforded by VE below the waterline, very few boats get osmosis above the waterline. If cost was not an issue i would of course use all VE but for the most part the higher phisical properties of VE or epoxy only matter if PE were not adequate.

Steve.

 

To be honest, I guess it is not really worthwhile. Also, the mixing can do strange things, as peroxides for vinylester can do funny things in polyester.

What does make sense, is to apply a good quality gelcoat (iso-npg), let that cure well enough. Then a vinylester skin coat (hand laminated) of 2x225gr/m2 low tex CSM. Apply peelply. After thorough cure, remove the peelply carefully. (small pull angle). Now infuse your polyester behind it. (either iso-npg, dcpd or iso).

In that case both workmanship and material quality is such that both cosmetical problems and osmosis are highly unlikely.

 

I was hoping to hear from you Herman, yes, that is certainly the conventional way but i just thought id throw the idea out there, maybe someone has tried it, its only something you could do with infusion. What i would really like to do is come up with a way of not needing to apply a barrier coat on a finished hull, just dewax, sand and antifoul. If i did the whole thing with poly i would need to barrier coat, which, with the labor and materials involved would probably more than make up any cost difference between poly and VE, im assuming i dont need to barrier coat when using VE.

Steve.

 

Whats the real difference in price from an infusion VE compared with an infusion PE?

Bear with me here,

but why do you want to infuse anything in the first place? i have many reasons personally... and with regards to cost, i can infuse cheaper than hand layed - popular opinion says infusion is more expensive, but i can fully PROVE otherwise.

Now consider VE vs PE and traditional thinking tells us that VE is more expensive, but consider the possiblitity that is actually cheaper, beyond the purchase price per bucket of resin that is... add up the extra labour, barrier coatings, logistics etc and then you really need to reassess your laminates aswell - you need to do this anyway because you are now infusing rather than hand laminating, and you have better mechanical properties with VE (and infusion method). I would be very surprised if VE worked out more expensive, when all things are fully considered.

 

Groper, i dont have quotes yet to figure the cost difference between VE and PE but i suspect the PE will be not much more than half the price in drum quantities. You will notice in my previous post that i said exactly the same thing as you regarding the cost difference when factoring in barrier coating the PE hull. Doing the skin coat with VE is probably the way to go and then infusing with PE if it works out that significant money can be saved. Is it really necessary to use as heavy a skin coat as Herman suggests to prevent print through with infusion? Ive seen it suggested somewhere that you get more print through from VE vs PE, is this so?
My reasons for wanting to do infusion are probably the same as yours, the ability to take our time in setting everything up neatly and being able to wet it all out with less people and not be rushed, much neater,better laminate,cleaner yada yada yada.

Steve.