Can any of you experiences glassers offer some advice on how to get a really clean free lap.
Normally when I glass a board I do the underside first and using a paint brush wrap the glass about 1" around onto the deck of hte board. Using the squeegie I do my best to remove as much excess resin from the cloth thats wrapped around the rails and on to the deck.
Then I glass the deck and just let the excess cloth just hang off the rail. After grinding down all the bumps there is always a section from the rail to 1" up the deck thats visibly darker coz of the laps.
If you look at any freelap board, pro or otherwise you will see the lap line. Some are better than others, the trick is not to pile the resin up where the two meet, remember the lam resin is just glue for the fiberglass, its not a filler. So forget the paint brush trick, just use a squeegee. Do super clean sissor work on the free lap, cut it so the cloth looks like a cut lap if possible. When you do the free lap make sure everything on the wrap is laying down flat and flush. Make sure when laminating that you don’t use excess resin that can drip or puddle, just enough to wet out and make it stick to the foam. Flip the board and prep the top, this means either carefully grinding or sanding down the free lap line, trimming all the strings that run out on to the deck etc. Do the top the same way except with your double cloth. Now you got a laminated board, take the grinder or a surform, surform is better for the meek. Surform down anything that looks like a bump…all the lap lines, bugs, dingleberries, and what not, you should only have to do the rails and a few zits on the deck and bottom. Press hard make it smooth, try to make it as smooth as the finished board, with practice this will become easier. Now hot coat, remember the hot coat is just to fill the little pinholes in the cloth weave, it’s just a filler that will be sanded off, and sanded smooth. sand, gloss, polish.
What makes the darker lap lines, or sometimes yellow lap lines, is the piling up of material. Or sometimes too hot of a mix, which will happen with UV if you leave it in the sun for too long, too fast. Sometimes its the brand of resin, sometimes it the kind of cloth? But if you do clean lamination work it will come out fine.
I think you are doing nothing wrong. It’s almost impossible to do an invisible fiberglass lap (maybe with an extra transparent resin with very very little MEKP=12hours to set). If laps (FREE LAPS) look weird to you I propose to let them set (not cure, just 1 or 2 hours), turn the board upside down and cut the laps with a new razor blade in a continuous cutting line, running parallel to the rail and 1 inch inside it. This is what is known as a CUT LAP, which is very common is resin tints (see Cooperfish.com).
If you are just starting it is way easier to tape where you want your laps to end with colored masking tape, then let the resin gel, lightly run a razorblade along the tape line and then let the resin harden completely. Once the resin is set, us a grinder or sandpaper with a little ascetone on it and sand along the tape over the razor cut. when you get close, pull the tape and magically you have even laps on the board (though it may need some touch up and extra razorblade help as you pull up the tape)
Make sure you use tape that will not absorb resin or allow streaks.
i don’t think it matters whether you start on the deck or on the bottom, as far as cosmetics are concerned.
if you are not setting off the resin too hot, and not allowing too much resin to pile up on the rail laps, then at the most , following hot coat and sanding, etc… the most you should see if you are going clear, is under scrutiny, a slightly thicker looking (darker looking) area where the freelaps cover each other.
so you are cutting the cloth so that you get about a 1 and 1/2 to 2 inch lap onto the deck and going the other way, onto the bottom. and then you are using a squeegee to pull the resin through the glass on the deck/bottom before wetting out the rails and laps thoroughly. you’re going back in about 5 minutes and making sure the rails and laps are saturated and using the brush to smooth out and remove any drops of resin that are starting to form on the rails, and you’re cutting off any hanging strings.
if you are using volan cloth then you will always get a darker…noticably darker…lap line both deck and bottom and on the rails.
if you are using e cloth then i’d look to see what weight cloth i’m getting and whether its a twist or flat weave.
a 4 oz flat weave should be about invisible. but it won’t be strong.
i’d say the problem is probably the weight and weave of the cloth. but again, you will have more cloth and more resin on the rails and lap, than on the deck and bottom, so in any application, they will be somewhat darker.
The key to a clean free lap is a clean cut on your cloth. Try to keep it even and level to the same strand all around. Uneven cuts result in stray strands hanging down. Takes extra time to deal with it and often winds up stuck to the deck in a long strand.