FIBREGLASS REPAIRS - AVOIDING CONTAMINATION

[gerrym]

Working on the Plus 2 Bodyshell, I've been careful to first clean with solvent any repair area, then sand or grind down to original laminate, then clean again with acetone and a fresh cloth, prior to any glassing in any repairs.

I now find I've been guilty of bad practise on at least two areas

1/ My cloths which are usually old clothing, may well be contaminated with silicon (used in some washing detergents) and or various plastics loosened by the acetone.

2/ Sandpaper, including recommended aluminium oxide, is sometimes treated with stearate to prevent dust clogging. Stearate acts similar to a "fat".

Both forms of surface contamination are highly undesirable to achieve maximum bond strength and minimum complications in the painting process.

Solutions seem to involve only using paper towels for cleaning and acetone wipedowns (and never tack rags) plus using sanding materials which are specifically labelled as stearate free. On this last point, I've checked the Norton website and they seem to indicate which papers are stearate treated.

Oh well, another piece of learning for me. Hope this helps someone else as well.

Note for reference on the above, check out the West Systems website.

Regards

Gerry

[TeeJay]

Hi Gerry.

Thanks for the heads up.
Very timely for me as I have just started paint removal and any resulting repairs.

[cabc26b]

Did you find out about the contamination after your first top coat fish-eyed or pin-holed ?

Trash and contamination are the home painters biggest hurdle in getting a profession finish.

Other tips I would offer -

Use auto body sanding paper - eagle/kovax is what I have used along with 3M

Remove all, and I meal all silicon bearing stuff from the work shop, Power wash the inside, let dry. set up the tent or drape the areas you don't want spray on , I cover the floor with contractor paper as well.

During priming I use prep-wiping solution from the paint supplier - use 2 rags - one to deposit the solution, the other to pick up the trash suspended in the solvent other wise you are just moving it around. do not re use the rags ( i buy boxes of cotton rags that look like mill ends)

before starting top coats I wash the entire car or panel really carefully with a mild silicon free detergent and fine bristle brush to loosen and remove what I can - I dry thoroughly.

next is the prep wipe recommended by the system I am using for PPG it's acriclean ( DX330 i think) I do it twice , let dry , start the top coat.

don't forget to filter and clean the air before it gets to the gun.


George

[gerrym]

George, no, I'm only planning on prepping and possibly filler/primer. Just don't have the space to setup a decent spray area. Are you based in the States, some of the brands you are quoting don't seem to crop up here. Will try and get some 3M paper though (non stearate coated "clog free")

However, I have had a repair that did'nt seem to adhere very well. I've also removed some of the original molding joins, presumably done by the factory. Worse was inside rear wheel arch where the top body molding was joined to the base body molding. The factory appeared to have made no attempt to prep the gel coat. Glass was applied directly to the gloss finish with big gaps just bridged over. Will post some photos some day.

Regards

Gerry

[Gordon Sauer]

I used Fiberglass Cleaner 202 (Interlux) from boat stores before glassing but interestingly for this most recent painting, where I had virtually no fisheyes, my final clean betwen priming and before color coats (always using a roll of automotive paper towels) after DX 330 (PPG) was Windex--saw it in several books and used it as final cleaner and seems to have done really well. Gordon Sauer