I have "repaired" the cracks on the tail of my beater twice and both times I've completely sanded off the cloth/resin. WTF am I doing wrong here? Once everything has dried, I start with 120 and get the rough stuff. Then I try to finish it off with 220. Should I just stick to the 220 the whole way?
i usually use a little more resin and about 2-3 layers of cloth. Remember its all gonna be sanded down
Yeah same here, but at some point the whole thing gets bumped off. I'm thinking I should stink to only fine grit paper.
you have to sand down (Prep) the spot before you add cloth and resin. When prepping the spot you need to sand down the area around it. Making a lower area for cloth and resin to sit. If when placing the cloth and resin it is above the surrounding area, like a bump. Then when you sand it down, making it flat and level, you will have sanded the cloth away. If its a deep dent you can fill it with q cell. Thats another thing in it self. I like to dip the cloth in the resin then place it on the board. rather than putting the cloth on dry and "painting it on". This IMO helps get it nice and flat. Use a squeegee if you want it nice and flat. Hope that makes sense and helps
If the area is not too big and you have to time during the day and there is ample sunlight you can use Sun Cure. Prep is important as mentioned ruff up the are a about a inch all round the damaged area I use 100 grit for it . Wipe the area down with a rag and rubbing alcohol to get any residue or dust off the area. If you using cloth and resin do as stated , put a coat on the area and then soak the cloth in it and apply . Multiple layer are best cause it give you room to fix as sanding. If you are gonna go the suncure path. Apply a nice size bead to the area in a Shade area out of direct light. Use a rubber glove to smoth it out and remove any air pockets in it . Dont worry if you cant get them all out cause if you sand you can always sufff it up with a rough grit and apply a second or third coast When sanding the area down it use these grits 100 get all the rough stuff smooth 180 to level it out 220 to get heavy scrathes smaller 250 400 wetsand 600 to wet sand to make it extra shiney if it has a gloss finish Dont worry if you mess it up or sand to much off you can alway add more or start from scratch again
If it is a crack, even a good size crack I pretty much repair it the same exact way MATT does it. I know there are a few types (brands) of the Sun Cure but get one with cloth fibers chopped up in the resin. The only thing I do different is after I put a bead of it the crack I use Saran plastic wrap. It make it real easy to smooth the resin over the area and the plastic wrap contours it over any edges or curves. After it cures it peals right off and is usually very smooth. I suck a ding repair but this works well for me, the plastic wrap takes a lot of the sanding out of it. A couple of times all I've had to do take a few minutes to sand the edges to blend them in.
Thanks guys. I didn't think about roughing it up beforehand, but it makes sense. I also think it is a great idea to dip the cloth in the resin, rather than painting it on. I always find that painting it on makes it hard to keep the cloth still. I'll give it another go this weekend and see how it goes.
Rough the area with AT LEAST 100 grit. I use 80, and sand it down to the weave around the repair. This makes a good cloth-to-cloth bond between the existing skin around the ding and the repair patch, and lowers the overlapped area to make a smoother transition from the repair to the old skin. Also, always do two patches... on the exact size and shape of the ding, and the other overlapping the ding, small patch going down first. Wet the area, apply the patches, pull out excess. Don't try to put the patches down dry, then pour resin on top of them. Resin, then cloth, then pull. Try to get out all the excess, so the patches don't "float." Once cured, fair the edges, then hit it with a hotcoat, then sand.
Thanks dude. I already do the two patches, one smaller then one larger. What do you mean by "hit it with a hotcoat" though?
After the patches are down and cured, and you've faired out the edges to make them smooth, you take a little resin and paint the area. It's called a hot coat because you can make it "hot" with a little more catalyst so it goes off quicker. Once your hot coat is hard, sand it smooth and call it done. To help confine the hot coat resin to the patched area only, tape it off with masking tape.
One more (dumb) question. I always thought you had to use the heat catalyst. I understand it increases the dry time exponentially, but do you really not have to use it? I always thought you had to.
You need the catalyst. Depending on the amount you add will determine the dry time. The more you add the faster it will harden. Now resin WILL technically harden all by itself. But it will take a loooong time. Like weeks. or longer.... I had a bottle of resin with a little left in it sitting around for a year. I couldn't get it opened so I cut a hole in it to try and get some out. The resin was like a solid rock. Test it out for yourself....grab a brush and paint on some resin without catalyst on something useless. You will see eventually it will harden. But it will take forever.
Ok, so you can mess with the ratios then. I guess there is also such a thing as drying too fast. In my case, I'm looking for dry time of less than 24 hours.
Drying and curing are 2 different things. Drying can be done in a couple hours or less. Curing well..... takes weeks.
A catalyst is a chemical that speeds up a reaction by creating a "short cut." Add more catalyst, and you get a faster reaction. You need catalyst for a proper cure when dealing with thermoset resins... which both polyester and epoxy resin systems are. "Thermoplastics" is another term you might hear. However, if you use too much catalyst, you will build up so much heat (exotherm - the heat generated by a chemical reaction) that you will alter the physical properties of the end product of the reaction. In the case of catalyst and polyester resin, you make the resin become brittle and change color. So... don't add too much catalyst! Ideally, you want a kick time of no more than 20 minutes. Even that's a long time. "Hot" batches should be much faster than that. Check the manufacturer's instructions on how much catalyst you can use, at what ambient temperature.
