BYYB Forums

Okay, guys.  I'm getting close to finishing!  I need to finish a few details in the cockpit, then it's time to sand, prime and finish.  I have two big questions!

1) What do I need in terms of paint volume to finish my Weekender?  My guess is 2 gallons primer and a gallon each of the hull color, white and maybe 2 gallons of spar var.  The Hull will be Interlux Flag Blue.  I think at least two coats.  The cockpit will be white.  The interior, and exterior brightwork all varnished.  Am I about right in the amounts needed?

2)  I'm ready to do some fillets to finish off the cockpit.  Do I need to use the same recipe as the glue (equal parts by volume silica and wood flour) or can I cheat with more wood flour and less silica for ease of sanding?  All will be primed and painted or varnished.

Dave

(04-18-2010, 06:32 PM)Dave Blake link Wrote: [ -> ]2)  I'm ready to do some fillets to finish off the cockpit.  Do I need to use the same recipe as the glue (equal parts by volume silica and wood flour) or can I cheat with more wood flour and less silica for ease of sanding?  All will be primed and painted or varnished.

I would use the same formulae.  The thing to do to reduce sanding of a fillet is to go back when it has begun to set and with a gloved finger smooth all the fillets.  You need to wait long enough that the fillet is firm but still plyable. 

Instead of wood flour, use Q-cells, West 407, 410 or micro balloons. Of course a touch of silica to stiffen it up will be necessary, but this mixture will sand just by thinking abrasive thoughts about it, much unlike wood flour.

A cleanly applied fillet, needs little sanding, so make a good fillet stick. Clean the dribblings on either side of the fillets right away, so you don't have to bother when it's hard. Lastly, when the goo has gotten stiff and is near the gel stage, use a very light wipe with a solvent soaked finger (put a glove on dummy), which will smooth out the fillet like glass. Some practice at this and you can skip sanding the darn things. Taping off the area on each side of the fillets with PVC or vinyl tape will go a long way to making smooth, neat fillets too. The trick is to work neat, so you don't have to sand.

I tried my hand at making epoxy fillets today using fine wood shavings,  the mixture I got was a dark brown peanut butter consistancy.  I shaped the end of a paint stick to make my fillets.  I'm going to have to get some micro ballons to try becuase I didn't like using the woodflour.

Wood shavings or the dust that comes off a sander is way too coarse for use in a fillet. It'll work in structural applications but it doesn't spread smoothly and is a pain in the butt to sand. You want talc, balloons and silica or talc, Q-cells and silica, trust me. The other option is to buy a pre-made mixture, like West System 407 or 410.

http://boatbuildercentral.com/proddetail...bf_1%2F8lb.

This is a pre-mix that works well.

Or you can use a pre-made filler like this stuff.



Naturally, you'll pay a lot more for the pre-mixed and pre-made stuff, but it does save the bother of mixing.

Paul:  What's the correct ratio of silica to microballoons?  I know there are premixed fillers out there but I have plenty of silica on hand, and will buy the microballoons.

Dave

I don't know what the correct mix is but I had good luck with a 1 to 3 ratio with silica and wood flour for construction and about a 1 to 6 ratio of silica and micro balloons from filling areas and fillets.  I did some bigger flat areas with just micro ballons and that turned out ok also. 

The correct mix is dependent on several factors, but in a nut shell you mix it to get close to the constancy you want with balloons, then add a little silica to stiffen it up. The average cosmetic fillet is mostly balloons, Q-cells and talc. The silica is just a thickening agent to keep it from sagging and running down vertical surfaces.

After you've mix a few batches, you'll get a feel for how much you need, per batch. I use mixing cups to ladle out the fillers. This way I can keep track of the amounts needed for the environmental conditions of the day. As an example the last batch I made for cosmetic fillets was about 6 ounces of epoxy, well mixed and poured into a wide, flat bottom 12"x18" plastic cake pan. This lets the epoxy spread out so it doesn't kick off on you too soon and gives you lots of room to mix the fillers in. Next I used two half cup scoops of balloons and started to mix. I use a "folding" action to mix as it's the fastest and most efficient method, just ask an old printing press operator or a good cook about "folding" in ingredients. This was mixed, but it still wasn't thick enough, so I added another 1/2 cup of balloons. When this is about stiff enough (between heavy cream and thin peanut butter) I added a 1/4 cup of silica, maybe less. The mixing process took about 5 minutes, then I spread out the thickened epoxy on both the bottom of the mixing tray and a piece of plywood that I use specifically for this purpose. Again, spreading it into very thin sheets will double you're working time in warm weather so get in the habit of doing this.

Some use the pastry bag method to apply the thickened goo. I think this is a pain in the butt. I use a putty knife and apply "beads" of goo the width of the blade to the corner. I find this is faster, neater and the epoxy isn't permitted to pool in the bag so it can kick off, but to each their own.

Thanks for that head's up Paul. That has been an issue with me, The epoxy allway's kick's way to fast, so I have to go like a madman to do the job at hand before it kick's. I am going to start using this method, I do remember waaaaaay back when I was in high school Body shop, we would spread bondo out like that.

Brian.