infusing with contour balsa

I received the slow catalyst but haven't needed it yet, the parts so far have infused so quickly ive had plenty of working time with the standard mekp. I believe that VE needs to be calatyzed at least 1 1/2%.

Steve.

 

I may be out of date here as I believe the resin has changed a bit and I'm in another country ! But we always used SR Catalyst at 1.5% for the best cure.

 

The first two parts have bee beliveed to the customer and all is well. I had a chance to take a couple of pictures of the up close to try to demonstrate the dryness refered to in my above posts. The pictures appear drier than the parts actually look but should give you some idea of the extent of the problem. To be clear, whent the edge was trimmed the laminate was tight and appears fully wet.

 

So did it look wet when infused & dry after/during cure? Or how does it look if you squeegee some resin into the surface.
It's a bit hard to see just what is going on. This look is why I haven't pursued infusion so far, I've seen laminates similar but apparently acceptable but at odds with my training decades ago.
I'm guessing at some issue along the lines of or combo of resin/binder, over vacuum? or reduction after first shot, moisture to timber core, catalyst/resin?

All the bet from Jeff.

 

Well most of the white colouration seems to be in the CSM... this could be binder or god know what because ive never infused a laminate with CSM in it. To give you an idea, this is how my laminates look with 2x layers of 750gsm triax (20oz i think?) stitched e-glass over a foam core;



These are nice panels but you can just make out an area of minute air bubbles trapped in the laminate which are concentrated around the core perforations and in a cross shaped line (right hand side) where the resin feed line was on the other side of the panel. This was caused by too fast infusion speed at the beginning of the infusion which didnt allow all the air to escape. Ive since learned to throttle the inlet at the beginning of the infusion to get rid of this problem...

Whenever i get a laminate which is very white, there is always a problem. Using CSM, perhaps the binder doesnt allow a proper wetout of the CSM fibres? There might be a special type of fabric you need to use with infusion so that the CSM binders dissolve more easily?

 

Just re-qualifying my lack of experience with infusion, ................ but so far as I know csm is not recommended maybe as like those "puckers" shown it can flow with the resin to a degree, Continuous filament mat is what they seem to indicate. I had some similar looking stuff going on with a job quite a few years back, fibre whitening/jackstrawed look to the laminates, liaised with the suppliers..... basically we were buying on price for cheapest csm(emulsion mat) & cheapest ortho resin, as often happens we ended up paying a little more for powder bound chop & iso resin from another source & started sending good stuff out the door instead of to the tip....................... much gooder!
Previously the laminates looked great until the resin kicked.... & then they looked up the ****
Just thinkin' out loud about stuff that can not go quite right.
Jeff.

 

How long is the vac pump running before you introduce the resin ?

 

I've done a sample with 3 layers 1.5oz matt and 1 layer 400gsm on either side with Ve resin,when cured it was clear,there was no white at all.

I'll post a pic when I get home tonight.

 

Thanks for the input guys, the first 2 pictures are of the tool side and the last 2 are the peel ply side, I don't think the csm itself is a problem but I do think where it is could be, by this I mean on our first test panel the csm side of the 1708 was toward the core on both top and bottom and it looked pretty much like Gropers panel but on the parts in the photos i put the mat side out on both sides in anticipation of sanding to prep for paint so when stripping the peel ply I think it lifts the fibers a bit which is actually what is mentioned by some of the suppliers as a reason to use treated peel ply. On the tool side i do think it has something to do with the mat but im not sure what. I think redreubens point is a good one, we have been starting the pump, checking for leaks and then introducing the resin when we probably should be trying to pull out as much air as possible first. Jeff, on the 1st panel it wet out nicely and then we noticed after we shut off the feed before the resin reached the edge of the part we started to see resin draining out of the green flow mesh,we had not found any leaks before infusing but it is possible one developed during the process. We didn't have this on the second part but the end result is the same. To be clear, there are no dry spots which could be wet out after the fact, they are very nice parts, certainly better than could be achieved with wet lam, just not as nice as Gropers or my 1st test panel. I am just starting on the mold for the 12ft x 6ft swim platform and plan on doing a few more test panels on the glass table before infusing it. The platform will be primarily all uni and the only mat was going to be a skin coat next to the gelcoat but I may leave that out.

Steve.

 

When you saw resin "draining out what was the vacuum pressure at that time?

On your gel coated part, I would gel coat then skin coat via wetlam in an unwaxed PE resin for a print blocker. Then infuse a purely multi axial laminate with no csm.

If you use a peel ply, you don't need to sand the laminate. I Spray a high build primer straight onto it after removing peel ply and then start sanding/prepping for final gloss.

 

Some pics,this is alternating csm and 12oz shade cloth for flow.


This is just 12oz 3 or 4 layers green flow media and unrestricted flow.I also clamped off a little early,i now let it get past the part and onto the peelply break before clamping.


You mentioned it went so fast that you felt there was no need for slow hardner.I think this is your problem ,it goes to fast trapping air.Groper sometimes knows what hes talking about

I have 40% shade cloth I think, this is much slower then the green mesh.

 

Vac pressure was about 28-29hg which is as much as I can get. My original plan had been to wet lam a 3/4 oz skincoat on the platform mainly to buy myself plenty of time to set up the glass and core for infusing, i will of course have everything pre cut but still. The only part where the gelcoat needs to be really good is the 4" turn down as we will be laying flexi teak on the top. I will be using all uni with no mat other than the skin coat and some good size areas of coosa board in place of the balsa where it will mount to the hydraulic arms and where the cradles for the Rib will be mounted, I will have to drill and groove the coosa myself. The underside will have extra structure added after the initial infusion and then just brush gelcoated.

Steve.

 

Tungsten, are you using a core? There are a couple of thing i think i should be doing, one would be running the pump for longer before introducing the resin and throttling back the feed at the beginning, ive been putting a valve in the bucket for this purpose but forgetting to use it.

Steve.

 

Steve, that much vacuum id say your boiling the styrene, it turns to vapour and then appears as bubbles in your flow media. It cant escape because the flow front is too far away by that stage, so it simply floats to the top and sits in the flow media. May have something to do with what your seeing, but it may be unrelated aswell, never the less a problem to be avoided.

Heres some reading on the subject -> http://www.vacmobiles.com/vapour_pressure.html

 

Groper, i think your on track there, if the look was simply some torn fiber from the csm layer when the peely ply came off, some resin would clear it up or even some water/spit would make it look good till it dried. The techs from composites suppliers indicate very little loss of strength & material properties from minor stuff...for example when you look at the core materials used, with balsa there's a range of densities/grain, with even quality foams there's inconsistencies in cell size so it really doesn't matter for non critical areas & still tuff enough. I've done a few crappy layups in my time but aim for nice clear, transparent clean looking work. As an apprentice one job we did regular was submarine hatches & casing repairs, the hatches were around 5/8"- thick & at about half that thickness cured you could see the black gel pretty clear, at full thickness more fuzzy. One of the neatest jobs I've seen was a Dragon hull laid up by Reg Gardner from Endeavour Yachts at Wallacia, hand laid, fully transparent & looked sweet all over. I know the fiber fractions get great with infusion & your epoxy laminates look pretty sweet, but from where I've come from a neat hand layup is a lovely thing
I'll get to infusion.............
All the best from Jeff.