I am ready to glass my redwood chambered fish with RR epoxy but not sure if I need to put a sealer coat on before I do the laminating coat.
Any advise would be greatly appreciated
Some people may disagree, but I’m a huge fan of a thinned sealer/cheater coat directly on to the wood
as temperatures are dropping.
I believe Greg recommends Xylene to thin Resin Research epoxy.
Have any pictures to show us?!
I just finished glassing a HWS (using RR) made from redwood. I made a couple of mistakes.
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I sealed the wood with de waxed shellac using a brush. I don’t know if my shellac was old, but it came out a little blotchy.
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I did free laps. You can’t see the lap lines, but you can see blotches where I sanded.
If I were to do it again I would either spray on the shellac (like Wood Ogre did), or do a seal coat with resin. The dark color of the redwood makes blotches more visible, so be careful.
One thing the I did do right was heat the epoxy beforehand. If you microwave the resin (not the hardener) for 10 to 15 seconds, then it will flow better. Otherwise, it is the consistency of honey during winter (temps 60 to 70 degrees).
Thanks Sweid, Nice board! I heard that redwood absorbs alot of resin that’s why I was thinking of sealing with resin first. I will try the microwave tip ,I live in S.D. too so I was trying to wait for a warmer day to glass. I’ll post some pictures
Thanks Afoaf, I’ll try to thin the RR for a sealer coat as day time temps here are in the low 50’s. I’ll take and post some pics too.
By all means seal whatever wood board you have before glassing it…
I’ve had no problems thinning it with denatured alcohol, maybe 1/3…
The heating/ cooling advice is solid…
Remember that the wood also needs to be the same temp as the epoxy, so keep it indoors until you’re ready to glass it. Even pre-heated and thinned epoxy thickens when it hit cold wood or foam.
No troubles with fish eyes? I’m about to use redwood for the first time as a stringer and am a littler nervous…I like the local/renewable side to it, however…
I would definaledly do a sealer coat, but you only need to use the bare minimum of resin, you actually want the wood to soak this up. you dont want any sitting on surface.
Heay resing yes, but don’t thin with DNA or use additive F for this step, you won’t needed and it will increase the chance of gettign the whities.
Put on a little at a time and spread it around with a hard squeege you’ll be surprised how far a little resin will go, pull any excess off, use can use scraps of glass cloth to soak up any little drips on the rails,
if you miss any, which if you use the right amount of resin in the first place you shouldn’e get any atall, but if you do you’ll need to wait till they are cured and hard before sanding them back or they will show up. If this happens just filp the boads and do the other side before coming back to them.
Heres another tip and a good one: don’t pull the resin from of the flats to saturate the hanging cloth of the lap as the whities show up at lot more over dark wood.
Instead use a 4" bursh, paint resin from the bucket along the rail then use the brush to fold over the cloth, wait for it to soak in, cut any hanging fibres and go back and hit any dry spots.
Even if the resin picks up bubbles as you pull any ecxess off as the laps are already saturated these sit on the surface and are easily remove.
Heat the resin (not the hardner), take your time mixing it so not to get bubbles, glass on a falling temp, don’t over work it on the board and wait it the resin is hard before sanding the laps, overnight is best, unless you glassed it first thing in the morning
Hope this helps, and remember we want to see pictures when its done.
I’m a house builder, and I know that when painting redwood, we always need to
seal it. The reason is that redwood has oils in it that will bleed through both paint and primer.
In houses we use shellac which is clear. Sometimes a high hide primer like kilz.
I know that epoxys don’t like oil. I would be afraid of the epoxy not curing right, or eventually
delaminating.
Swied mentioned that his shellac came out blotchy. I think that there was a problem with his shellac,
because I’ve never seen that problem on my window sills and siding.
Woody has it right. I glass sheathe cold moulded boats fairly regularly. They are made of anything from mahogany to western red cedar.
Beware applying resin to wood as the ambient temperature rises, air in the cells expands and leaves bubbles on the surface. I often apply the resin then warm the surface with a air gun and when bubbles appear just knock them off with a fine brush. Best to get the glassing done when the sealer coat is still active / tacky, you get a better bond and the glass wont move around under the squeegee.
If the wood is very resinous then alcohol or acetone works fine but make sure it has ALL evaporated off before glassing otherwise you trap the solvent and it will vapourise and form bubbles under the glass days later or when left in the sun.
Rik
Quote:
Swied mentioned that his shellac came out blotchy. I think that there was a problem with his shellac,
because I’ve never seen that problem on my window sills and siding.
I think you are probably right. My shellac was probably too old, which caused the bloching.
Given the high cost of epoxy I’m wondering why people seal their boards with thinned out epoxy instead of using shellac. Also, wouldn’t sealing the board with epoxy make the board heavier? The only person that I have heard of that uses the shellac technique (in this forum) is Wood Ogre.
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there are a couple possible reasons for shellac to spot or cloud and they are easy ot prevent. First thing to do is check to see if the shellac is still good. just wipe some on wood, if it is completely dry after 2 hours its good to go. First off I use Zinsser Bullseye seal ceal. 100% de waxed. The truth is there is not a bonding problem if you were to use waxed shellac. It’t just that dewaxed is water resistent. waxed is not and will water spot or cloud if it gets wet. Waxed shellac is easier to sand. If you want to make your own dewaxed shellac you can just put shellac in a clear jar with cover and the wax will settle to the bottom in a few weeks and you can de-cant the clear off the top-thats dewaxed. Back in the old days I used to make my own using shellac flakes. But thats just to much work. Brushing shellac is a pain in the butt because it drys so damn fast.So you get some places where it is thick and some where it is thin and almost always get streaks. If its waxed shellac you can sand it out. If it is de waxed you will get some sand through and you wont even notice untill you are finished and then you will see blotching or cloudy spots and guess what ? It will get more noticeable over time . The best solution of is to spray shellac. I spray 2 light coats and don’t sand after. You can do your sanding before spraying and then sand out you resin after but don’t sand the shellac. If you cant spray then wipe on the shellac. The shellac you get in a can is about a 2 pound cut and is a bit thick for wiping. Thin it half shellac and half alcohol and wipe on 2 coats about an hour between coats. don’t try to build a surface coat. If it dose not soak in you have to much, there should be no surface coat. For me the purpose of useing shellac is to keep the wood from soaking up all that resin which just adds weight. The shellac has a stronger bond than epoxy resin anyway. I use shellac a lot and have been doing so for over 40 years. They have yet to invent a better sealer or bonding coat. I love it under water base finishes because it prevents most of the wood gain raising. Have any ??? Ahui hou- Wood_Ogre