Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: Forwardhandle on May 21, 2018, 01:02:01 PM
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I'm currently finishing off 2 glass bows and I'm sanding the limbs & risers to 220 grit and using Duplicate-color clear coat but it got me wondering if there is any finishes that can go over the factory coating on the glass with out sanding it, I have friends that use pre catalyzed magna lac on other types of bows and claim it will stick to almost any surface ?
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Maybe with shellac or a vinyl sealer as a bridge coat, but you still have to prep the old surface by cleaning it. Why not sand first for insurance, stripping a finish gone bad really sucks.
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I am sanding & using clear coat I was just curious if there where non sand finishes
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As an aircraft metal worker and painter, I'll tell you what my trainer told me. Your paint job is only as good as the surface you put it on. With that in mind, if there was a no-sand finish I wouldn't trust it.
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Definitely take the couple extra minutes to sand it! Even if someone makes a product that can be applied directly, whos to say the fiberglass coating isn't going to let loose from the glass.
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Thanks guys I was just thinking the manufacturer puts the sealed coating on and the wood lams are not this is my first glass bow and I got it shooting perfect where I want Im just nervious about sanding glass...lol Chris your bow looks awesome I was really thinking of a oil type finish in the future like tru-oil but now I know to sand. Like said I was just throwing it out to learn
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Thanks Ritchie. Sorry I could have typed that better, came off kind of jerky. I meant it as a caution more than anything. When you sand the glass use something like 320-400 and only sand it enough to get rid of the factory glossy spots. Once all of those are covered in the light scratches from the paper just wipe it down really well with isopropyl or denatured alcohol and double check it to make sure all the smooth areas are gone. After the light sanding the glass should have a kind of cloudy look to it but you should still be able to see through it if it was clear glass. I know your bow will look amazing no matter what finish you put on there, can't wait to see some pictures!
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I didnt take it as jerky Chris, I could relate to your aircraft analogy I have owened two small airplanes over the years been a private pilot for 44 years and had one painted so I see your point on prep work , finishes have never been my strong point but its a interesting topic to me !
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I agree with the beast on the 320 to 400 for glass. I know many builders do 220 and it's just fine but 320 is finer {that there is a pun :) } My current approach is to sand the entire bow except the glass with progressive grades of paper until the wood is finished to 320 and then do the glass with the 320. Colored glass looks fine under the auto clear coat and the clear is clear.
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Well on this one it's brown glass I'm going to have to do 220 grit because I ordered a 25 sheet pack from one of the web stores that should get here tonight , but on the other bow maybe I will try lighter grits both are hunting bows so doing the Matt finish , hoping to get one done with the long week end !
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Finaly found a can of this ,the matt is hard to find but was reading the can , it says it takes 7 days to fully cure ! [ You are not allowed to view attachments ]
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Hey Ritchie, I think that is what I sprayed my bro's bow with, it wasn't a great finish. It showed white marks with any scuff ,scratch, or bump.
He refinished the bow last winter after one hunting season .....
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Yeah Bro... I would not just use any finish unless approved by a couple of the boys... VHT wheel finish has a couple of decent reviews... Someone did a thread on here about it... (I think Monty) IMO... Min-wax Poly in the rattle can does a good job but it yellows... The water base does not yellow but I never used it on bows and don't know how it will go on or hold up... Don't use Deft... I don't like the stuff... Anywhere the string layed against the limbs it left a mark...
Sand the glass... Don't worry about changing or ruining your tiller... You are gonna have to do a lot of sanding to do that especially with 200-300 grit... Glas is some tough stuff... Follow Monty's instructions... Wood first, down to 200-300 and then the glass on the flat area... Save the edges for last and do them very lightly because they can sand fast and change your bow by a pound if you sand and round them too much...
For future reference... When joining surfaces or applying finishes almost all surfaces get sanded... In most cases this is more or less called mechanical bonding... There are exceptions where you don't have to sand... These are called chemical bonds or welds... A good example is gluing together pvc pipe... Another is spraying on a second coat of auto finish before the first coat fully cures... These are chemical bonds...
Good Luck Brudder...
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Thanks for the education guys I appreciate it, this is what I have on hand , also the wife has water based polly in her inventory , I have seen Truoil used on other glass threads has any body here used it ? I have used it on many self bows with good luck very durable finish and if you want the matt look pumice powder and olive oil mix works great after its cured ,I also have spray Shellac & other pollys ? , my wife is offering to chalk paint it for me 😳 [ You are not allowed to view attachments ] [ You are not allowed to view attachments ]
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I always thought the coating on the smooth side of fiberglass was a "release agent" to keep the fiberglass from sticking to the mold when it's made?. That's why we sand it off before we apply finish. When choosing a finish one important thing is knowing what you are applying the finish over..meaning are you applying finish over a "oily wood" like Bocote or other Rosewoods. Some finishes like Minwax Spar Urethane do not "cure" over oily woods unless you first seal them with something like a dewaxed Shellac like Bullseye. So back to the original question about sanding the release agent before applying finish..yes, I hand sand it with 320 grit but used to use 220 grit.
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So whats a good recomendation for finish ?? I would like to do it this week end if possible other wise I will hold off tell I figure it out ?
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I'm not sure about bow glass, but aircraft glass comes out glossy like that as well. Ours comes out that way because of the heat resistant nylon films used to build the vacuum bag that compresses it. While it doesn't have any release agent on it, the glossy surface causes paints and other coatings to bead up and run off because it's so smooth.
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I've used Varathane water-based Spar Polyurethane satin spray on a bunch of bows, and have been very pleased with the results. Quickest, easiest way to finish a bow that I've tried. I strongly recommend using only the satin version, not gloss or semi-gloss. It's very fast and easy to use. I apply 5-6 coats, waiting only 5-10 minutes between coats. I typically spray everything but the back glass first-- that way I can put the bow down on the back glass between coats. Before spraying the back glass, I let the last coat on the belly, sides and riser dry for at least an hour. After that, the finish on the belly has dried enough to that you can set the bow down on the belly side of the limbs and then spray the coats on the back glass.
This stuff gives a nice uniform finish. I never sand between coats-- just spray, wait 5-10 minutes, and spray again. When fully dry, the satin finish isn't glass-smooth-- it has a very, very subtle texture. Nothing like an actual textured finish-- it's very subtle. After the final coat, I let the finish cure for at least a day or two. It may not need that long, but I figure if I'm going through the trouble, waiting a day or two before using the bow is no big deal.
It's water-based, so it doesn't give wood that warm amber glow that oil-based poly does. Just yesterday, I sprayed a Hill-style longbow with Eastern Red Cedar limbs and Hickory riser. I wanted to give the cedar and hickory the ambered look, so a few days ago I applied a couple of coats of Minwax oil-based gloss wipe-on polyurethane to the wood surfaces (not on the glass) and let it cure for a couple of days. I then applied 5-6 coats of the Varathane water-based spar satin spray over the entire bow. No sanding of the wipe-on poly or between the spray coats. The bow turned out great.
Here's the stuff. The stuff I got recently has a new label-- it's now got a green label. I buy it at Menards.
https://www.homedepot.com/p/Varathane-11-25-oz-Clear-Satin-Spar-Urethane-Spray-Paint-6-Pack-250281/202057150
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Other posters are right about sanding the glass-- sand with 320 or 400 grit to dull the glossy surface before applying a finish. I really like 3M sandpaper (the purplish or yellow colored stuff you get at Menards or Home Depot; the package has "3X" or "7X" or "10X" on it-- meaning that it lasts that many times longer than cheap stuff). I find that the good 3M 320-grit paper removes stuff faster than cheap 220-grit paper while still leaving a smoother surface. And it does last a lot longer than cheap sandpaper.
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Just a heads-up-- the Varathane water-based spray doesn't go on in fine misty coats. It looks kind of splattery compared to what you may be used to-- not bad, just not super-fine misty look. But don't worry, it looks good when it dries. Don't lay it on thick-- move the spray fairly quickly along so that it doesn't go on too thick. Applying 5-6 coats will cover nicely.
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I used Minwax Spar urethane before I got set up with an oiless compressor and spray gun. I use Krystal from Big Jim now. Krystal works over any wood even if its oily and dries in minutes.. If your used to using Truoil then maybe that's a good choice for you.
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I like Tru-Oil. Have used it for gunstocks and bows. If thinned 50/50 with paint thinner and applied in several thin coats there is no need to sand or steel wool between coats and you get a smooth hand rubbed oil looking finish for no additional effort.
Here is one I just refinished and posted in the auction.
(http://i.imgur.com/AvhDb04.jpg?1)
(http://i.imgur.com/phzP5xi.jpg?1)
(http://i.imgur.com/AInlABT.jpg?1)
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Thats a nice looking bow there Joe I have used tru oil as a finish for a while very tuff finish I only make hunting bows so I make a paste of pumice powder & olive oil and rub a nice matt finish, I just wasn't sure if it would work on glass, Im assuming you where talking thinning for spraying ? If I where to use it I was just going to hand apply !
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Not sprayed on. It was applied with a piece of cotton t-shirt. The thinning makes it much more user friendly than straight and the thinned coats lay down nice and smooth even with a rag. It dries faster and multiple coats can be applied each day so overall it doesn't take any more time. That riser was sanded to only 220 and the finish was not worked between coats or after the final and looks like more than 220 was used. I didn't keep count but there's probably 7-8 coats on it. I have used the thinned Tru-Oil over existing factory gunstock finishes without any prep as a touch up that came out looking like a lot more effort was put into it so it would probably work over the existing glass finish without sanding.
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Ok thanks Im still going to sand the glass too, but sounds good on the application 50/50 how long between coats ?
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Guess it would depend on temp and humidity but I was able to apply two coats in an evening so about 4-5 hours. Even if a little bit tacky it still works as the previous coat has smoothed itself out by then. I think the thinned mixture penetrates into the wood better and seals the pores. The first few coats are dull and then it starts to get some body to it. If you get the sanding prep clean I think you will find it is a no fail application as there's nothing else to do but apply very thin even coats and wait.
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Also on one of the bows I was thinking Pre catalyzed lacquer I have friends that use it on composite & glass bows they swear by it any body here try it ? It's supposed to be really durable finish !
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Got the first coat of Tru oil & denatured alcohol didnt have paint thinner & the alcohol is compatable on the charts but the riser took it in nicely [ You are not allowed to view attachments ]
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:thumbsup: :thumbsup:
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Thanks Kenny with the alcohol its flashing off quick should be able to get a couple coats today in between honey dues 😃
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Coat #2 this finish is giving me the old school rustic look I was after, you can tell the wood keeps sucking it up as it keeps getting darker ! [ You are not allowed to view attachments ]
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Cool. Never would've thunk denatured alcohol and TruOil would work together.
Learn something new every day here. :)
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Got the info from guitar makers forum the say denatured alcohol , mineral spirits or paint thinner work so far so good !
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Coat #3 cut the alcohol back to 20% these coats are drying to the touch quick hot as heck here with a nice breeze in the shop [ You are not allowed to view attachments ]
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Honey dos!! It’s the weekend man!! Tell her to let up! :biglaugh:
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Ok I will tell her see if it works ,I only have 30 more bags of mulch to do & weed and I can put another coat on 🤢
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Here is 7-8 coats I switched to strait tru oil for the last 3 now let it set for a week and mix pumice powder and olive oil and rub it matt this finish less the alcohol I have used on many self & sinew bows its a tuff finish , Im going to buy a paasch air brush and try some thing different for the 60 in. I just have to switch bows and convince the wife Im still working on the same bow 😃
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Here is another finish question I have Kennys 60 in. Forward handle design its Zebra wood but I want to try the Pre cat lacquer finish but do you guys know of any thing I can do first to really pop the grain off before spraying the Pre cat lacquer ? [ You are not allowed to view attachments ]
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Dewaxed (seal coat)or decanted Amber shellac would do the trick. As would a vinyl sealer. Are you using a Nitro based Lacquer or CAB acrylic? If you have spray equipment, you might look into using a conversion varnish, it's bomb-proof and chemically cross linked, similar to epoxy finish.
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I think in the pre cat lacquers they use acid as the catalyzer all though the say vinyl sealer can be used on top of them but not recomended going over shellac its supposedly good solid bond and is avalible in matt finish in rattle can or liquid.
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Flem thanks for the info I just ordered some vinyl sealer, I'm going to use it as a base coat in conjunction with the pre cat lacquer sounds pretty water proof seal it sounds a lot easer then the conversion varnish !
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I just got this in the mail I will try it out this week end , Im learning a lot about finishes on the guitar makers forums , this as a base coat toped with pre cat laquer is supposed to be a really tuff water proof finish , I was going to buy the liquid and spray both but the pre cat lacquers have exasperation shelf life so the rattle cans are more economical ! [ You are not allowed to view attachments ]
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Got the other part of the finish today hope to get both on this week end , sounds like this stuff should be a durable hunting finish, will see !
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I really like this vinyl sealer here is two thin coats the grain is starting to pop this stuff has a strong chemical smell real strong like breathing acetone moved it out side but drys incredibly fast !
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Im waiting for the preverbal paint to dry so figured I would post this is 4 coats vinyl sealer scuff sanded 320 grit & 1 coat Pre cat lacquer ! [ You are not allowed to view attachments ]
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Very nice, Ritchie.
:thumbsup:
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Thanks Roy Im going to try the same finish with brown toner on the hickory/bamboo bow next I was thinking maybe sun burst on it but to time consuming will see !
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Done 4 coats vinyl sealer 4 coats pre cat lacquer I think I just found my go to finish 😃 [ You are not allowed to view attachments ]
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Looks great Ritchie! Think I'll have to give this a try.
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Well it was Flem that made me aware of it Chris ,cant take credit but its pretty user freindly not cheap but looks great, I will have to see how it wares I have friends that use the pre cat lacquer solo and swear by it the vinyl sealer really water proofs it ,I like it , the only down side is it exspires so you need to purchase close to use !
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Here it is after resting over night this finish feels like a hard matte egg shell is on the bow [ You are not allowed to view attachments ] I'm trying the same finish with toner for the bamboo backed bow next !