Your assumption only really becomes an issue if the glass cloth is overloaded with resin (be it epoxy, vinylester or polyester) when the peel ply is first applied. I experienced a similar problem when moulding my enterprise, and believe me, the small overlapping lines were the least of my problems!!
If you’ve ever followed one of Claudio’s builds in the past, you will note that he’s very precise with the amount of resin needed for a certain type/weight of cloth. I think this reduces to a minimum the chances of overlap lines etc.
Yours,
Row
Claudio - you’re really putting the pressure on me now! My ‘Enterprise’ is now filled and faired and I’m currently experimenting with the internal ballast casting. Will hopefully have some results in a week or so and will put relevent info on my build log.
Sylvain,
the ribbons are removed about one hour after the lamination when the resin is soft enough. Probably this is the reason why I do not get hard steps.
Meanwhile I faced a “mini disaster” !! The 1/2 hull was sticking !!!
With the glass laminated blades I managed to remove step by step the 1/2 hull.
Certainly, under these conditions, a full laminated would had resulted in a “total disaster”.
The chemistry occurred between undercoat, acrilic black paint and Mirror Glaze 16 wax.
The master was standing there since several months therefore full dry.
Actually I suspect the black paint in conflict wit the wax.
Beacause of that I will start sanding out the black paint all over before continuing the lamination of the 2nd half !
I’m quite surprised to see such a ‘severe’ reaction with the paint. As you may recall, I experimented with various release compounds and resins before molding ‘Enterprise’ and it was only when using epoxy that the problems disappeared. I don’t know what wax you’re using but I didn’t experience any adverse reactions using Meguiars Mirror Glaze number 8 - which was used over an acrylic paint. You have my sympathies! I guess it’s nothing that a little ‘elbow grease’ won’t resolve.
Very impressed by the weight of your molded half hull - I used a layer of 290 gsm sandwiched between two layers of 165 gsm, which now seems like over engineering. If I mold another one I’ll try to find some much lighter cloths. At the moment your finished bare hull will be half the weight of mine which may allow you to increase the ballasting bringing associated improvements when sailing.
Here I’m again after 2 hours of wet sanding and elbow exercize, the Black paint is gone !!
Row, is the first time for me too. The wax is the Mirror Glaze 16 that I use since 5 years without any preoblems. Actually I’m pertaining to the group of 15% of sticky moulding !!!
Next I think will be packing tape !
ClaudioD
Just did a close inspection of my plug - cleaning up prior to re-waxing aft end of keel to make molding to ‘fill the gap’ - noticed that there was evidence of a reaction between paint and/or wax and/or epoxy. It’s not immediately obvious (doesn’t show up in a photo) but the weave of the lighter twill cloth that was the first layer has left a slight imprint over approx 70% of the surface. Lesson learnt - acrylic paint is not really suitable as a finished mold/plug surface. I guess on this occasion I was just luckier than you. We live and learn…
I had similar experiences to your results Claudio and found the problem was not present when I used PVA release after waxing the mould. One other point is PVA realease has a life of 6 months so be aware, old stocks may cause problems.
Claudio your idea of packing tape is no doubt the safest route …
Hi Claudio
Do you drape all the lays over the mold and then wet them all out at once or do you wet out the first lay then put the second lay on and wet it out etc?
Thanks
Don
Hi Don,
the second option is the one, but is not the easiest, since the wet layer tend to stick to the second one , therefore there is the need to manipulate carefully the tisue application without disturbing the existing layer. Not easy, requires some experience expecially with this type of hull. A class M is much simpler .
On the other hand , I never tried to wet all the tissues at once and I do’nt knows if this method give good results as well.
There is some great info about mold prep and releases in the composites forum at rcgroups.com. If you can’t use PVA, two part paints are MUCH more reliable than single part paints. Wax is a good release, but it is NOT a barrier to prevent any chemical reaction between the epoxy and the paint. PVA is a barrier as is" packing tape" (Mylar).
I know it is hard to get a perfect finish with PVA, but packing tape should be worse, with the little ridges, no?
It is a beautiful hull, though. I love the classic era of the America’s Cup.
I agree that bicomponents paints will work better so far are not polyurethane ones but are also more expensive against the quantity I use.
According to my readings, the chemical reaction is taking place between the wax and the paint, expecially if of polyurethane type.
The technical data sheet of wax manufacturer contains ‘specific warnings’ about their wax and paints compatibility and suggest to make some tests before, something that I did’ nt.
It is also true that the free epoxy molecules that did’ nt entered in the reticulation process , are crossing the wax barrier and sticking with the solvants if any.
The above picture show that the packing tape ribbons do not exibit ridges on the outside surface. Probably the packing tape I use is very thin , so much that I can’t even measure it.!
Since I decided not to use PVA in female moulds, the habit is kept even for others techniques. I prefers to use wax in general, and with the lesson learned to use now the packing tape on polystirene base materials. Wooden plug with wax but no paint anymore.
Cheers
ClaudioD
Before I molded ‘Enterprise’ I carried out a few experiments regarding release agents and resins as Claudio had cautioned me about possible reactions between paint and some waxes. My initial results were somewhat disheartening as I was hoping to mold using poyester resin. Anyway, I tried various combinations of wax & pva, just wax and just pva and all effectively resulted in failure. Discussions at the time suggested that the solvent (styrene) in polyester resin was able to migrate through the various ‘barriers’ and interact with the acrylic paint (surface finish of plug). Bearing this in mind I was surprised to see that you included pva as a barrier - in my experience it wasn’t, however a further molding of the keel area showed beyond any doubt that packing tape definitely was (using polyester resin). My problems were eventually resolved by switching to epoxy resin and using a wax release.
Hope this doesn’t come across as critical of your comment - it’s certainly not meant to be - just wondered if you could clarify the pva / barrier thing.
First, what width packing tape have you used? And second, how did you get it to lay so evenly over the various curves of the hull? I remember when I was making a separate molding of the keel area of Enterprise and had a nightmare of a job getting the tape to lay smoothly.
Different thing altogether now, but this morning I managed to successfully cast a usable ballast for Enterprise (will post details on my build log in the next few days). Once it was cool enough (bucket of water) I placed it into position and was struck by initially how heavy 4Kg of lead is and then by how relatively flimsy the hull is. I keep having thoughts about when it’s finished it’ll be sailing in the middle of a lake and the ballast will just drop out of the bottom!! Is this a product of an over active imagination or are you planning some additional reinforcing of the keel & bilge area?
When I’ve used tape on multihull hulls, like one would do with wood veneer layups - place at an angle to allow tape to take compound bends - especially where there is a severe change in form. This tape is so thin - (mine is) that you can feel the edge on the inside of the glass using your fingernail - but it isn’t so thick as to transfer through the glass cloth to the outside of a single layer of cloth. I use either 2 layers of 4 oz. - or for light layups - a single layer of 4 oz. and an external layer of 1//2 or 3/4 oz. glass cloth. I always use epoxy - never polyester - as I know what to expect from epoxy and have been using it since late 1970’s. Note - for really “strange” compound curves you can always cut tape narrower (like you can cut balsa strips) to take the bends in two directions.
Dick
in the photo - you can see I angled the tape slightly and also where I applied a second piece
Hi Row,
the packing tape roll is 48mm wide and as said before the tape is very thin , the picture take may show what about.
Obviously it is necessary to reinforce the keel area with additional laminations, partial shadows and traversal plates. I will prepare a skecth since I need it also for myself.
I will not insert the bulb inside the keel since my choice is the " hang-on" of the external fin blade + bulb. This option, while not elegant when out of water until is not removed, will allow to adjust the dept of the bulb by sliding the fin blade like on simpler monohull like M or similar.
Below a sequence of pictures showing as I apply the packing tape.
I start by fixing the tape to the deck line level.
On one hand I hold the roll and with other hand I use the fingers, tumb or index, making soft pressure while sliding progressively until the the top.
In case of little buble is sufficient to pierce it with a pin.
Cheers and pass on the finger.
Demouldig very easy and this are the results including the actual weights of each single half .
A close-up of the inner surface , shows the induced packing tape steps. In my opinion comparing withe 80g/m² tissue waiving, the step should be less than 0.1mm. The outside surface do not show any steps .
Recomposing the two half hull.
The carton wedge was first cut away in order to be reused again as spacer. Alle taken with stamples and paper scotch.
From now on the separation line will be filled in with some charged epoxy . This operation will be done after complete polymerisation of the last half hull.
ClaudioD
Fantastic work as usual, and I’m sure that if my hull were split down the centre line the difference between the two halves would be rather more than 7g!!
Many thanks for the tape explanations, especially the bit about using a pin. It was incredibly frustrating trying to chase bubbles to an edge to get rid of the little blighters.
Keep up the good work & I look forward to seeing you keel reinforcing ideas.
