seam filler

Used the elmers wood putty filler I had seen on trf as a seam filler
Question I have is can you thin it down with something to spread it into fine cracks better? It is rather crumblely to work evenly into the thin seam lines.

It's water soluble so thin it down with water. When I use it, I like the consistency of thin pancake batter and brush on. Lately I've been using Bondo spot putty instead. I'm not sure yet whether I'm sold on one or the other. Both have a +/- as to application as well as sanding qualities.

What about the PPGproduct they call "Icing"? And there's also something similar called "spot putty" that I used to use when filling in very small discontinuities in car bodies...

Are these acceptable, useful, etc?

The elmers product i am referring to is water soluable and didn't think you may be using the type that comes in a small can. I think you may need acetone to thin that.

The Bondo spot putty I use comes in a tube and is pre-mixed.Are you referring to two-part bondo? I imagine that would work just fine and probably preferred for larger projects; however, I have not used two-part bondo myself on rockets.

spot putty tends to attack Estes plastic nose cones. 'bondo' is some nasty stuff (IMO), mix about 1/3 - 1/2 as much as you think you'll need and you'll probably still have to mix more because the 1st batch got hard(short working time).

I believe water was the answer I was looking for
Thanks I will try that approach - trying to keep it simple but get good results

El Cheapo said:

The elmers product i am referring to is water soluable and didn't think you may be using the type that comes in a small can. I think you may need acetone to thin that.

The Bondo spot putty I use comes in a tube and is pre-mixed.Are you referring to two-part bondo? I imagine that would work just fine and probably preferred for larger projects; however, I have not used two-part bondo myself on rockets.

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I've used the Bondo (pre-mixed tube) on a couple of rockets and for me, it goes on and sands nicely, especially when I have to smooth out joints where two BTs were coupled. However, the fumes get pretty strong by the time you finish filling the spirals on a Batray's body tube. I decided to not use it any more until it warms up enough that I can have the garage doors open while I'm working.

It's kind of like cutting onions. You never lean over the cutting board. I practice the same principle when using spot putty as well as soaking parts with thin CA. Seems to not really bother me. That or all the acetone and brake klean I have used over the years has numbed me to that effect.

A ratio I read about for Elmer's wood putty is 2 1/2 cups of putty per one cup of water. That seems to work quite well for brushing into balsa, basswood, and body tube spirals. I've had pretty good results on body tubes and basswood with a single application. Balsa seems to need 2 applications depending on the density.

FC

I ve read a bazzilion ways to fill seams spirals whatever ya call-em. Anywhoo-It hit me (not hard). Drywall Joint Compound aka. MUD. well,I didnt have any on hand or in garage for that matter. So I went and picked up a small bucket ,like $2.49. I tried it last night on my Tomahawk Quest BT.Those Quest BTs are some rough if ya ask me.I havent primed it yet,but it seemed to work great.Easy to apply, fast drying and sand VERY easy..Plus its white(ish) and wont take a lot to cover.(Ive used red and green auto putty and it seems to bleed thru until you got an inch of primer over it)Its made for paper and wood...so seems to me, why not????? Ya, its on the messy side sanding,but what isnt when ya get down to it. I also tried it on some balsa. Ill put the primer to it and let ya know how it worked out. Seems a bucket for 2.49 is darn cheap and will do a boat load rockets.

Scotty Dog said:

I ve read a bazzilion ways to fill seams spirals whatever ya call-em. Anywhoo-It hit me (not hard). Drywall Joint Compound aka. MUD. well,I didnt have any on hand or in garage for that matter. So I went and picked up a small bucket ,like $2.49. I tried it last night on my Tomahawk Quest BT.Those Quest BTs are some rough if ya ask me.I havent primed it yet,but it seemed to work great.Easy to apply, fast drying and sand VERY easy..Plus its white(ish) and wont take a lot to cover.(Ive used red and green auto putty and it seems to bleed thru until you got an inch of primer over it)Its made for paper and wood...so seems to me, why not????? Ya, its on the messy side sanding,but what isnt when ya get down to it. I also tried it on some balsa. Ill put the primer to it and let ya know how it worked out. Seems a bucket for 2.49 is darn cheap and will do a boat load rockets.

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Not to sure about the MUD. Very soft and didnt get into seams all that good. Didnt cover well with primer or seal up.maybe if I mix in some powdered plaster. hey ,its worth a shot.

Here is a video link of Tim Van Milligan thinning the wood filler, painting it on fins and sanding. He also uses the filler to fill in spirals in the body tube. It is part of a 5 part video on making a rocket. It would probably be useful to watch all 5 parts

https://www.apogeerockets.com/education/downloads/Building_Avion_2.mov

Rex R said:

spot putty tends to attack Estes plastic nose cones. 'bondo' is some nasty stuff (IMO), mix about 1/3 - 1/2 as much as you think you'll need and you'll probably still have to mix more because the 1st batch got hard(short working time).

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I used Bondo Glazing and Spot Putty (the regular, not the Professional) on the seam lines of a Fat Boy nose cone for my Der Fat Max and on my Alpha's nose cone. There were no compatibility issues with it and it didn't "attack" the plastic in any way. I used it straight out of the tube and just smeared it onto and into the seams. It certainly adhered to the plastic better than Elmer's Carpenters Wood Filler did.

When I do use CWF, I smear a bit onto a plate and then drip water onto it, mixing in a few drops at a time until it reaches a "paintable" consistency. Then I use a cheap, fine tipped paintbrush to apply it to the desired areas (usually tube spirals). The brush gets it in right where I want it to go while minimizing overflow onto adjacent areas. Less overflow translates into less sanding later on.

The two-part Professional version of Bondo Glazing and Spot Putty does indeed give off some really foul polyester resin fumes, which seem to be triggered when the hardener is mixed in. The regular formulation (in the big red tube with no accompanying tube of hardener) is much more benign and user-friendly. The regular version is all pre-mixed and is meant to be used straight out of the tube. It is distinguishable by a deeper red color and a (potentially) longer pot life. (You have to be real quick with the Pro version because it cures very fast once it is mixed. Pot life isn't really a concern with the regular stuff since you don't need to mix it up in batches.) I would still suggest wearing a dust mask when you sand it, though, because sanding does produce a large quantity of very fine powder that goes everywhere. (CWF does the same thing when it is sanded, too.)

Scotty Dog said:

I ve read a bazzilion ways to fill seams spirals whatever ya call-em. Anywhoo-It hit me (not hard). Drywall Joint Compound aka. MUD. well,I didnt have any on hand or in garage for that matter. So I went and picked up a small bucket ,like $2.49. I tried it last night on my Tomahawk Quest BT.Those Quest BTs are some rough if ya ask me.I havent primed it yet,but it seemed to work great.Easy to apply, fast drying and sand VERY easy..Plus its white(ish) and wont take a lot to cover.(Ive used red and green auto putty and it seems to bleed thru until you got an inch of primer over it)Its made for paper and wood...so seems to me, why not????? Ya, its on the messy side sanding,but what isnt when ya get down to it. I also tried it on some balsa. Ill put the primer to it and let ya know how it worked out. Seems a bucket for 2.49 is darn cheap and will do a boat load rockets.

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Using a howitzer to kill mosquitoes.

Regular (pre-mixed) Bondo G&SP has a bit of an acetone smell when it is fresh out of the tube, no doubt reflecting the fact that acetone is used as a solvent in the mix. With average use, the overall smell produced is about a third to half as intense as the fumes that are created when your wife or girlfriend cleans the polish off her fingernails.

Scotty Dog said:

I ve read a bazzilion ways to fill seams spirals whatever ya call-em. Anywhoo-It hit me (not hard). Drywall Joint Compound aka. MUD. well,I didnt have any on hand or in garage for that matter. So I went and picked up a small bucket ,like $2.49. ... Seems a bucket for 2.49 is darn cheap and will do a boat load rockets.

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Well, if you want to talk price, a small tub of Elmer's Carpenter's Wood Filler lasts me well over a year. After that I usually have to throw it out even though it is sometimes still half full because the remainder has turned to stone. A little bit of CWF goes a really long way because you thin it down so much before using it.

MarkII said:

Well, if you want to talk price, a small tub of Elmer's Carpenter's Wood Filler lasts me well over a year. After that I usually have to throw it out even though it is sometimes still half full because the remainder has turned to stone. A little bit of CWF goes a really long way because you thin it down so much before using it.

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Funny,ha,ja,ha.The Mosquitos up here are SOOOOO.. BIG....you need a Howitzer to kill-em. Got me a tub of CWF just last night.Price is rite as you stated.The thing is,it doesnt hurt to try dif ways,products,ect.Im not saying one is better than the other...to each his/her own.What ever works for you.Some rocketesrs dont care about the finish.Ive seen many pics where they didnt fill anything. Thier rockets fly just fine.

As many have said already:
There are as many ways to fill woodgrain and body seams as there are modelers out here trying stuff.

The thing that gets me is we seem to talk about this subject over and over without much agreement which I believe is because everyone has different tolerelnce levels to smells, and or aversion to overspray or mess.

For many years as an apartment dweller I used Pactra (now Midwest) Balsa filler which is very different then balsa sealer. Filler has lots more solids in the vehicle which is the material that actually does the "filling". Problem is the smell. Personally I don't have a problem with it but others in your home might
Bondo and other Automotive fillers are usually 2 part plastic/hardner component product that may or may not be compatable with our hobby. they all including the very thin red spot putty tend to CRACK under vibration or stress load unless you mix in some chopped Fibreglass or use it on or over glass cloth. Not a good thing in seam filling.
Drywall and lighter Ceiling spackle or fillers can work but have the same basic problems as spot putties then tend to crack with stress unless reinforced with some sort of filler threads.
Fill n finish if thinned can be used nearly smell free and does a pretty nice job. it's just too dang slow for my taste.

my preferred method is Cheap, rattle can auto primer. spray on 3 coats, let dry. sand, if needed spary on 3 more coat and sand.. I've yet to need more then 6 coats to fill the worst body seams or balsa grain. downside...OVERSPRAY containment and smell. If you have the option I believe it's the quickest and cheapest method of filling body and wood seams. Works even better with Basswood and other less grainy materials.
Hope this helps

Here is what I do for models where I really want to get rid of the seams (usually only for scale models, I do not bother with the seams for most sport models)

I use masking tape to mask off the whole tube EXCEPT for the seam (if the seam has a 1/16" gap, then there should be a 1/16" gap between the masking tape on each side of the seam). Then use a good primer to spray a coat that will go only into that seam. Some builders like Plasti-Kote Sandable Primer--available at auto stores--as it is easy to sand. Others have success using Krylon's white sandable primer, which is more easily obtained but can have problems with clogging up the sandpaper too quickly.

I will note what I wrote the above (and some of the below) for a short article years ago, before they had to change formulations of solvent-based paints like Krylon’s sandable primer (and probably Plasti-kote’s), so beware how those specific primers may end up.

After letting the primer dry fully, apply more coats (letting dry fully between coats) until the buildup of the primer will be a bit taller than the seam recess depth was (in other words, slightly above the rest of the masked-over body tube surface). Then remove the masking tape and apply a couple of coats of white primer to the whole tube. The primer paint filling the seam should be visible as standing above the rest of the white primer on the tube. Use sandpaper to knock down the primer covering the seam and make it flush with the primer on the rest of the tube. Don't overdo it. When the seam is pretty much flush, give the whole tube another coat or two of white primer and sand the whole tube until it's uniform, no hint of the seam left.

Even if a person is using something else, and not primer paint, to fill the seam, the masking tape idea is useful. Whether using a filler compound, or putty, etc., use something like a putty knife, old credit-card, or piece of stiff plastic, to scrape off all excess so all that is left on the tube is flush with the masking tape (do this as you go, while the filler or putty is still fresh and soft enough to scrape flush). You can remove the tape before the putty dries hard, but do not sand until the putty is fully dried out and hardened.

BTW - Before using anything like wood filler or other compounds or putties NOT made for use with models, it would be a very good idea to apply some so a scrap piece of tubing and let it fully harden. Then sand to see if the stuff actually BONDS to the paper tube. I cannot recall what it was, but many years ago I used some type of filler that did NOT stick to the tube very well, so parts of the filler inside of the seam came out during sanding. I ended up using spray primer after all.

- George Gassaway