[ace mcfee]

I built Sig's 1/4 scale clipped wing cub this past winter and covered it with Koverall and filled the weave with Minwax Polyclylic. At first I was going to paint it with latex but I did one other model and spraying it was a big issue and the drying time was too long for my patience level. Besides, even with a clear coat, latex still does not adhere as well as other finishes. So I decided to use good old Tremclad white and blue. I have had good success with Tremclad for cowlings and other smaller pieces like struts etc. but never painted a whole airplane with it before. I wanted something that was fuel proof, easy to get anywhere and easy to use.

I used a good auto sandable primer called Duplicolour from Canadian Tire, sprayed on one coat and sanded it lightly before applying the Tremclad. The base colour went on well and seemed to adhere just fine until I started masking and painting the sunbursts on the wing. When I removed the automotive masking tape, off came the two coats of Tremclad and the primer as well, right down to the fabric. I used a heat gun in an attempt to remove the rest of the tape, but that still didn't work so now I have a mess on my hands.

It seems to me that the primer I used did not adhere very well to the Koverall/Polycrylic finish. To remove all the paint is impossible at this stage so I have decided to fill and sand the imperfections caused by the removal of the tape and then try painting the sunbursts once again.

What I need to know is what filler is best to use on the fabric/Polycrylic/Tremclad areas; what primer should I use over the filler that the Tremclad will stick to.

I guess you live and learn in this Hobby. My previous experience in painting a multi-coloured model was years ago was using Perfect Paint and a Miller spray gun. That worked just fine.

Thanks for the help.

Ace

[Guest]

I hate to say this, but the problem is simply the paint.
I know guys want to stay on the affordable side, both paint and equipment wise, but there is nothing from Canadian Tire that is suitable for model airplanes, cars, etc. Spray your outdoor furniture, a rusty kids bicycle frame, whatever will never need masking or perfection. But Duplicolor is a horrible product. Tremclad is great for it's intended purposes but not model airplanes. Latex's can be used, but again, they aren't designed for airplanes. The best model paints for people who don't want to go the base/clear route on fabric is still dope. I don't even know if it's available anymore though it's been so long since I sprayed it.

The biggest issue you had with your primer adhesion though is going to come down to a poorly prepped surface. Even fabric needs to be thoroughly washed with warm water and a good soap with NO perfumes or oils. Tide powdered stuff is the best. Then it needs to be scuffed lightly with a grey scotchbrite pad. Then wiped down with a degreaser like PPG's DX320. Your primer coat can then be applied. Rattle can paints like Duplicolor should be left at least a week before spraying over and masking, and they should be sanded with 600 grit paper or at least a scotchbrite pad again before painting.

At this point, I can't help you "repair" the area's other than to suggest wet sanding the peeled edges with 800 grit paper, and trying to blend the primer and color back in. Unless you strip all the paint though you will still run into masking issues. If you don't want to strip it, give it at least a full week to cure before you attempt any further masking.

[vonJaerschky]

I can't help you in saving what you've already done, but I can say that Nitrate dope is probably one of the best primers for fabric. Most paints stick to it very well. And as I personally learned at the school of hard knocks, if you are changing your finishing method in any way whatsover from a proven method, always, always, always test on some scrap material first before trying it on the finished model!

[ace mcfee]

This is really good advice. The bad layer is the primer to the fabric. I agree that Dupli-Colour sucks and will never use it again. I know about the always test first rule, but got impatient and am paying the price now. I knew better, but was hoping that it would all work out. Back to the tried and tested ways for any painted models in future. Ace

[wymbly1971]

Hi Ace,

I had the very same problem but for a slightly different reason. I placed a part on the bench and part of the paint was still wet. When I removed it, that portion of paint and primer stayed behind and exposed the fabric.

My Koverall was sealed with nitrate dope. I used NAPA brand automotive filler primer (for another reason...but that's an unrelated and long story). Tremclad out of the can never hardens very well and dulls in time. For that reason, I use Tremclad mixed in the same proportions as Centauri with harderner and reducer.

Other than the peeled incident which was my own bonehead fault, I find the finish highly durable and holds its gloss well, even when exposed to fuel. If anything, the finish may be a tad too hard as it tends to crack up when you cut the openings. (maybe next time I'll try 1/2 the hardener).

My "intended" mode of repair for the bald spot (only 1/4" in diameter) is glazing putty in several thin layers, sand and touch up paint (airbrush?). After a week or so, I will colour sand to match.

I also find when masking, it is better to let the base set really well and then "dull" the tape. basically, rub the masking tape once through your fingers so that it will not adhere as well. Then remove the masking tape when the new coat is still soft. If the new paint hardens, removing the tape will almost certainly take more paint with it.

[mtnflyer]

I would just like to add, that I believe the quality of your masking medium is important. Tape made by Tamiya is expensive, but, well worth the price as its designed for modeling. It burnishes down very well, dosen't allow seepage, and removes without ripping your paint off the model. I have 1/4" and 2" Tamiya tapes that have never, ever given me issues. Normal masking tape has.
With anything else, patience is a virtue, and adequate drying time is very important.